Solar Energy


Overview

The primary purpose of Solar Roadways is to generate clean renewable energy on roadways and any other surface that can be walked or driven upon. That would include: parking lots, sidewalks, driveways, tarmacs, plazas, bike paths, playgrounds, garden paths, pool surrounds, courtyards and the like.

There are many longstanding uses for solar power, which are terrific. The SR concept takes solar technology to a new level. The idea is to collect the substantial solar energy which hits these surfaces but is currently not being utilized. In this way, they will have a dual purpose: modern infrastructure + smart power grid.

In the U.S., the highway infrastructure is in a dismal state. Solar Roadways was awarded a Phase I SBIR (Small Business Innovative Research) contract by the USDOT to research the viability of creating a highway system that would pay for itself over time through the generation of renewable energy. After completing two contracts with the USDOT, it is apparent that this goal is viable. SR panels can become the nation’s smart grid, providing energy to homes and businesses along the way.

Currently, most state DOTs (Department of Transportation) are no longer generating enough income through the gas tax to be able to keep up with road repairs. The last few decades have brought dramatic technological changes to cars, cell phones, computers, cameras, and many other technologies, but roads remain virtually unchanged.

It is obvious that it is time to modernize the highway system and create the first roadway system with a return on investment (ROI). In this way, two goals can be accomplished simultaneously: the creation of a modular, modern infrastructure while creating the renewable energy needed to effectively end the current dependence on fossil fuels.

Energy Production

The U.S. has enormous energy needs. The U.S. Energy Information Administration states that:

“Primary energy consumption in the United States was almost three times greater in 2014 than it was in 1949. In all but 18 of the years between 1949 and 2014, primary energy consumption increased over the previous year.”

They give more detail:
“Primary energy includes petroleum, natural gas, coal, nuclear fuel, and renewable energy. Electricity is a secondary energy source that is generated from these primary forms of energy.

Primary energy sources are commonly measured in different units: one barrel (42 gallons) of oil, cubic feet of natural gas, tons of coal. To compare across fuels a common unit of measure is used. The United States uses British thermal unit, or Btus, which measure fuel use by the energy content of each fuel source.

Total U.S. energy use in 2013 was about 97.5 quadrillion Btus. One quadrillion equals 1015, or one thousand trillion. One quadrillion Btus, often referred to as a quad, therefore represents about 1% of total U.S. energy use.

In physical energy terms, one quad represents 172 million barrels of oil (about nine days of U.S. petroleum use), 51 million tons of coal (about 5.5% of total U.S. coal consumption in 2013), or 1 trillion cubic feet of dry natural gas (about 1.4% of total U.S. natural gas use in 2013).

Petroleum accounts for the largest share of U.S. primary energy consumption, followed by natural gas, coal, renewable energy (including hydropower, wind, biomass, geothermal, and solar), and nuclear electric power.”

It is apparent that renewable energy, including solar energy, currently meets very little of the energy needs for the U.S. Solar Roadways® is emerging as solar technology is advancing and costs of solar cells are declining – a perfect combination.

Using very conservative numbers, calculations indicate that if all driving and walking surfaces in the U.S. were converted to Solar Roadway panels, they could produce over three times the electricity used in the United States. In fact, just the "lower 48" could almost produce enough electricity to supply the entire world. To see more detail about those calculations, click here.

There are many misconceptions about solar energy production. People often ask: “How many panels will it take to power my house?” or “How much energy will one panel produce in a year”? The answer to both questions is “It depends on a multitude of variable factors”. For example, a driveway in Minnesota is not going to generate as much energy as the same sized driveway in Arizona.

It’s easier to think about panels in terms of wattage. For instance, the solar prototype parking lot we created in our Phase II contract with the USDOT with SR2 panels is roughly equivalent to a 3600-watt solar array.

Each of the SR full-size hexagonal panels covers an area of about 4.39 square feet. The SR2 panels were approximately 36 watt panels. The new SR3 panels are 48 watt panels. There are also half panels (24-watt) and quarter panels (12-watt).

The amount of power produced depends entirely upon the amount of sunshine available, so in addition to the variable of location discussed above, other variables include: the degree of shading, season/time of the year, time of day, and other local microclimatatic factors. It’s normal for solar gain to increase in sunny seasons and conditions and decrease when less sunshine is available. Potential customers will want to understand what they can expect from their exact location in each season as well as the averaged amount per year.

The next factor to understand is the ratio between driveway and home or parking lot and business. Obviously a situation with a long driveway and smaller home will have a much better chance of energy independence, than another customer’s short driveway with a large home. How much energy one typically uses must also be taken into account. SR will provide customer service to help each potential customer understand what they might expect.

Another factor to consider is that SR will always have the flexibility to use whatever solar cells meet the criteria of offering the most efficiency at an affordable price point. SR panels will become even more efficient over time as new technologies become available to keep up with increased demand for energy with population growth.

If Solar Roadways® becomes the new smart grid - the backbone of the energy delivery system, all forms of renewable energy can be welcomed into the grid with ease. A common problem with centralized renewable energy projects is their difficulty in transferring energy to the grid. SR can facilitate this energy transfer, since roads are universally available and could offer widely available connectivity.

The EPA: describes the problem this way:

“The absence of standard interconnection rules, or uniform procedures and technical requirements for connecting renewable energy systems to the electric utility's grid, can make it difficult, if not impossible, for renewable systems to connect to the electric utility's grid.”

They go on to describe another obstacle in renewable energy generation and their connection to the grid:
“Many renewable resources are located in remote areas that lack ready or cost–effective access to transmission. States that have not established clear utility regulations that enable investments in transmission to be reimbursable (i.e., cost recovery), nor coordinated planning and permitting processes, slow the development of utility–scale renewable projects in their territory.”

Solar Roadways® can itself produce massive amounts of renewable energy if decisions are made to implement it on a major scale. It will always be important to support and facilitate other forms of renewable energy as well.

Power Line Safety



Currently, power lines are either up on poles where they are susceptible to damage from storms, or buried in the ground. If they are up on poles, wind can knock them down. Ice can collect on cables, causing breakage and power outages. Utility workers have to climb poles to access them for repair and are sometimes hurt. If the lines are buried, the utility workers have to dig them up with shovels, not knowing exactly where they are. Gas lines are often nearby, posing a danger. Solar Roadways® Cable Corridors offer a solution. There are two sections: one for cables and one for water. The cable section offers a “home” for cables where they are safe from environmental hazards and easy for utility workers to access (locked to others). Power outages could become a rare event.

Decentralization and Point of Use

Most energy systems are centralized. They provide power from a central location and send it out via transmission lines over a long distance. This leads to a substantial loss of that valuable energy. Examples of centralized systems include nuclear power plants, coal-fired power plants, wind farms, large solar arrays, etc. Centralized power plants create security risks because they are more vulnerable to attacks by hackers, terrorists, etc. They are more susceptible to damage from natural disasters as well. Entire sections of a country can be left powerless.

A decentralized system such as SR offers greater security. Much of the power is used near the power source - i.e., driveways power homes, parking lots power businesses, etc. Excess power produced by this system can feed surrounding neighborhoods. This helps with security: even if a section of roadway is completely destroyed by some type of disaster, both sides of the now damaged road still produce electricity - no one loses power. National security can be enhanced in every country.

Just as eating organic food produced in closer proximity to one’s home reduces transportation costs (and enhances health), there is a similar advantage to using power that is produced close by. Since driveways, sidewalks, patios, and parking lots supply power to homes and businesses in close proximity, less energy needs to be transported over long distances, resulting is less loss. Smaller cables are required, saving materials and therefore costs. In the SR system, the power is produced closer to the point of use.

Return on Investment

Just as highways can have a return on investment, home and business owners can do the same. When one purchases a standard driveway or parking lot, it begins immediately to serve its purpose: to provide a strong, flat place where people may drive and walk safely. That is it. It begins to lose value immediately, just like a new car when it’s driven off the lot. It produces no energy and gives nothing else of value to the customer.

SR panels offer a wealth of benefits, starting with energy. They power homes and businesses with clean energy. They do even more. The LED lights embedded in the panels make painted road lines obsolete. They offer flexible line, signage, and even decorating options across all SR applications. Read more about LEDs here. The heating elements in the panels prevent snow and ice accumulation, providing safer surfaces for both drivers and pedestrians. Read more about heating elements here.

Rooftop solar is another terrific option for home and business owners. One difference is that SR panels are a hybrid replacement product; they provide energy like rooftop solar while also providing an aesthetically pleasing alternative driveway surface. The panels become the road, become the driveway, etc, whereas traditional rooftop solar panels are an additional expense after one has paid for a roof, and they must be taken down when the roof needs to be repaired and then reinstalled. Many also appreciate that SR panels are easier to access, with none of the danger inherent in installing and maintaining panels on roofs.

Energy Storage

When it comes to the storage of the renewable energy produced by SR panels, customers will have a variety of options. A virtual grid system can be used with a specialized meter from the utility company that provides net metering. These meters spin backward when extra energy is produced. In turn, energy can be pulled back from the grid when needed to power the panel’s LED lights and heating elements at night, or in a storm when the panels may not produce sufficient energy. That is the system used for our first prototype parking lot and it’s working very well. Batteries were not selected for use in the SR2 parking lot, since they tend not to be environmentally friendly and using the virtual grid spares one that purchase. One downside to this system is that there is no energy available during a power outage due to the fact that the micro-inverters disconnect when they don’t sense energy on the existing power lines.

Those who want to have a storage system can incorporate most any kind of renewable energy storage for use along with their SR panels. Many potential customers say that they plan to use the new Tesla Powerwall, or other types of batteries. Any standard renewable energy storage device should work and could be placed in the Cable Corridor for easy access, if customers wish to incorporate them.

AC/DC

Solar cells produce DC energy. Homes and businesses currently use AC energy, so the DC solar energy is converted to AC energy by a DC-to-AC converter. Unfortunately, every time a conversion is made from DC to AC (or AC to DC), losses occur in the conversion. This means that some of the energy produced by solar cells gets lost when it's converted to AC for the home.

Many, if not most, of the electronics in our home don't actually run on AC. They are plugged into an AC outlet, but then a circuit inside of the electronic device converts the AC to DC before using the power, creating another energy loss.

If solar energy became the primary energy source, then it would make sense to convert homes and businesses to DC. That way, the power produced by solar driveways, parking lots, roads, etc. wouldn't be wasted by being converted from DC to AC and then from AC back to DC again.

Since heavy duty DC motors are available, all common household utilities could be run on DC power. Appliance manufacturers would save money by eliminating the AC-to-DC converter circuitry that they would no longer need. That savings could be passed on to the consumers. Less power loss and more savings would be win-win solution.

Greenhouse Gases and Climate Change

It is estimated that approximately half (different agencies provide different estimates, but the average is about 50-percent) of the greenhouse gases that are causing climate change come from the burning of fossil fuels (primarily coal) to generate electricity. Solar Roadways, if widely adopted, therefore has the ability to eliminate half of the greenhouse gases currently being produced. This would reduce pollution, make the air we breathe cleaner and safer, eliminate the ramifications of dependence on fossil fuels, and help slow climate change, which most scientists now agree is happening much faster than anticipated.

Facilitating the Transition to Electric Vehicles

A Solar Roadway is an electric road that can recharge electric vehicles (EVs) anywhere and with clean energy from the sun. Traditionally, EVs are charged with fossil fuels, much to the chagrin of EV owners who are often environmentally conscious. EV owners will be able to charge EVs with clean renewable energy at home with the help of solar driveways, patios and the like, and on solar parking lots at restaurants, and while shopping, for example.

Transitioning to electric vehicles is important for many reasons. AAA writes, in their website Making America Stronger:

“Driving is part of the American way of life. All told, we own more than 254 million road vehicles and we travel an average of more than 9,000 miles per vehicle each year. Virtually all of these vehicles are powered by petroleum-based fuel. As other countries adopt our lifestyle of freedom and mobility, the global demand for oil increases. Dependence on unstable areas of the world for some of our petroleum supplies can result in economically disruptive oil price shocks and could potentially constrain our ability to respond appropriately to national security concerns.”

They add this statistic about petroleum:

“According to the U.S. Department of Energy, petroleum supplies 99% of the fuel used in cars and trucks today. Gasoline and diesel prices continue to fluctuate as more nations modernize and compete for limited oil supplies.”

They discuss how renewables can help:

“EVs replace energy from imported oil with electricity that is produced in North America, and this benefit is magnified when that electricity comes from renewable sources such as nuclear, hydroelectric, wind or solar power. Over time, EVs will become even more environmentally friendly as additional renewable energy from other technologies is added to the power grid.”

Solar Roadways® can add that clean solar energy to the grid, allowing EVs to charge on clean energy from the sun, reducing dependence on fossil fuels of all kinds. This can have a positive effect regarding climate change too.

The Intergovernmental Panel on Climate Change writes:

“Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.”

They add this warning and potential solution:

“Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks.”

Implementation of Solar Roadways® on a grand scale could help bring about those “substantial and sustained reductions in greenhouse gas emissions.” When enough SR highway infrastructure is in place, another option will become available. Consultations are ongoing with companies that make mutual induction plates to charge EVs while they're driving (at least one has tested successfully at 75mph). The Solar Roadway could charge the EVs while they're traveling, which would increase their range. It’s quite simple - the "receiver" plate gets mounted beneath the EV and the "transmitter" plate is installed in the road. Currently, there is no delivery system for such mutual induction plates on highways, but Solar Roadways can solve that. With an infrastructure in place that will finally make EVs practical, people would likely start trading in their internal combustion engine vehicles for EVs.

Eventually, this system will eliminate an additional 25-percent of greenhouse gases that currently comes from vehicle exhaust, giving SR the potential to eliminate 75% of greenhouse gases with universal adoption.

Electrical


Overview

Solar Roadways® (SR) has a complex electrical layer. Electrical components are placed on a circuit board that is then enclosed between two pieces of glass and hermetically sealed to protect the sensitive electronics. The solar cells, heating elements, and LEDs are covered thoroughly in other sections. This section covers the other electrical topics.

Energy Storage

Solar Roadways® customers will find that many types of energy storage can be incorporated for use with the SR system. The SR2 prototype parking lot installation uses virtual storage (grid) model. Excess energy is sent to the grid during daylight hours. Then power can be drawn back out of the grid at night. This flexibility is perfect for SR, as solar energy is only available during the day, and the heating elements and LEDs need access to power at night. This also avoids the expense of adding a storage system. It’s also ideal for people with concerns about the environmental friendliness of batteries

Solar Roadways® is compatible with energy storage devices. Home batteries can be used if customers wish to incorporate them.

Energy

SR generates clean renewable energy. There has been some concern as to who owns the electricity produced by Solar Roadways®.

The short answer is, whoever owns the property, e.g., for driveways, patios, sidewalks - the home owner, for parking lots - the business owner, for airport tarmacs- the owner of airport. The ownership of roadways is convoluted: they can be owned privately, by the city, township, county, state, or federal government.

Smart Grid

Solar Roadways® can replace all current centralized power stations and become the smart grid for each nation, with sufficient installed infrastructure. The Cable Corridor remedies the need for unsightly utility poles. The Cable Corridor that runs alongside Solar Roadways® can provide a home for utility lines. Power lines, telephone lines, etc. can be placed within the Cable Corridor. This can significantly reduce outages from storm events. This would also provide easy access to all systems, making maintenance and repair simple. The safety of utility workers who must now climb poles and dig for cables buried in the ground would be increased. Landscapes would be unmarred. Power can be generated everywhere - from all walking and driving surfaces.

A decentralized system offers protection from outages. Much of the power is used near the power source (e.g.- driveways power homes, parking lots power businesses, etc.) Excess power produced by SR can feed surrounding areas. Even a disruption in the grid (road) will cause significantly less outages. Since both sides of the now damaged road still produce electricity, fewer lose power.

All walking and driving surfaces supply power to homes and businesses. Less energy needs to be transported over long distances, resulting in less energy loss. It also means smaller cables are required, saving materials (and therefore costs). SR produces the power closer the point of use.

Some have expressed concerns about theft. Each panel has its own microprocessor, which communicates wirelessly with the surrounding panels. They monitor one another for malfunctions or problems. If someone were able to pull a panel out of the road and load it on a truck, the stolen panel would continue communicating with all of the other panels in the road. The road would know exactly where it was and how fast it was moving. The panel would literally lead the authorities to the thief.

Road Safety

Weight sensors are electrical devices that can be used to determine the pressure on a surface. This technology works, but has proven to be expensive to implement. SR is designing their own technology, which will be integrated to the panel design upon its completion. Adding these sensors to SR panels essentially turns each panel into a type of scale. They can sense objects of (or above) a certain weight on the surface of the panel and the microprocessors can take any programmed action; this can warn drivers of potential hazards in the road.

As a pedestrian steps off of a sidewalk and onto a SR crosswalk panel, the microprocessor signals to the other panels in the crosswalk that someone or something has entered the crosswalk. All of the panels in the crosswalk can then flash until the pedestrian has safely reached the other side. The SR panels can also warn oncoming drivers. The road panels in front of oncoming cars can tell the drivers to "SLOW DOWN", in letters illuminated in the road's surface. The rest of the road can incorporate these sensors as well. The road could warn drivers of moderately massed objects in the road, e.g., a person, an animal, a fallen tree, a large rock, etc.

Repairs and Maintenance

SR is modular, so repair will be much quicker and easier than our current maintenance system. Each panel assembly weighs less than 100lbs (45.36kg). A single operator could load a replacement panel and respond to the scene. The panel could be swapped out and reprogrammed in a few minutes. The damaged panel would then be returned to a repair center. In order to redirect traffic with minimal disruption, the operator could quickly redraw the LED road lines to create a detour, and just as quickly put them back to the default position when he or she is finished.

Solar Roadways® has a microprocessor located approximately every 2.5 feet. Since neighboring panels also communicate with one another, if a problem were to arise, the road would report it to a central control station.

Durability and Disasters

Solar Roadways® is specifically engineered for road use. SR panels are designed to last a minimum of twenty years. Solar cells are the limiting factor: they can continue to work up to 30 years, but they are less efficient toward the end of their life cycle.

Each panel can withstand great variations in temperatures. The electronic components are made to endure high temperatures. The microprocessors can endure temperatures from -40⁰F (-040⁰C) up to 257⁰F (125⁰C). During Solar Roadways® current USDOT contract, the panels will be tested in environmental chambers.

Each Solar Road panel is hermetically sealed to protect the electrical components. The panels can be completely submerged, and the electrical components will be protected. This is a preventative measure for flash flooding.

In the event of lightning, the entire system is well grounded. Since the Solar Road panels are at ground level, lighting is far more likely to hit a nearby tree or other high point. In addition, glass is an insulator (non-conductive), so lightning is very unlikely to strike it.

Some have inquired how SR would be impacted by an electromagnetic pulse (EMP). An EMP is a burst of electromagnetic radiation that results from an explosion (usually from the detonation of a nuclear weapon) and/or a suddenly fluctuating magnetic field.

SR can shield against an EMP as with any other type of electromagnetic radiation: with shielding and proper grounding, which can mitigate or eliminate the effects of EMP. Shielding places a conductive surface between the source of the EMP and the electronic components. When the harmful radiation encounters a conductive surface, energy is transferred from the magnetic field into the conductive surface and shunted safely to ground. This leaves less of the energy available to be transferred into the circuit. Protection diodes, which provide a low impedance path around low voltage circuitry, can also be utilized to minimize the effects of inductive voltage spikes.

The electronics in SR will be hardened against external interference for a variety of reasons. In theory, if a massive EMP event (such as a nuclear bomb) were detonated above the Solar Roadway® (or any other electronic system) the damage caused could be significant and difficult to predict. The advantage of a system like Solar Roadways® in such a scenario lies in its decentralized nature. As described above, the decentralized grid can help prevent outages because energy would be produced everywhere and used close by. The increase in power required to disable the system increases on an exponential scale with increased implementation. Unlike the centralized energy production which is quite susceptible to this type of interference, a decentralized Solar Roadways system would offer more protection against EMPs than current centralized energy systems.

EVs and Autonomous Vehicles

The transition to SR and electric vehicles will be a lengthy process, but a worthy endeavor. Solar Roadways® can provide the infrastructure needed to charge EVs, both statically (parking lots and driveways) and eventually dynamically (on roads and highways, while driving).

The actual implementation of mutual induction technology which will allow EV’s to charge while driving is really quite simple. SR can provide the infrastructure needed for mutual induction plates. They can be installed in: roadways, parking lots, driveways, etc. EVs could charge in multiple locations, thus lengthening their range. EVs will then be charged by the road while driving. This means that they won't need large batteries, which will lighten their load and require less power to go the same distance. This mutual induction technology already exists, but there is not yet an efficient delivery system. Currently, plates would have to be installed in asphalt roads and power delivered to them, causing timely and expensive retrofits. SR can provide the delivery system, making EVs convenient, even in cross country road trips. In this way, Solar Roadways® can facilitate and speed up each country’s transition to EVs.

Autonomous vehicles are also an emerging technology. The SR team was invited to have a ride in the Google driverless car. It became apparent how SR could facilitate the transition to these vehicles. SR panels have microprocessors mounted permanently, meaning they have a fixed longitude and latitude. This offers a very special method of knowing exactly where a driverless vehicle is. This replaces the need to depend on satellite communications (GPS for instance) to determine location. It is much more accurate. A system could also link the location of each SR panel into its map application and use them to plot routes. Eventually, the Solar Roadway® could drive the vehicles.

Summary

The electronics in SR are specifically chosen to be both cost effective and of high quality. Anything extraneous is eliminated. The electronics are selected with other technologies in mind, so the integration of mutual induction charging, EVs, and autonomous vehicles will be simple. The electrical components will incorporate new compatible technologies as they emerge.

Glass


Overview

Solar Roadway® panels are made of tempered (safety) glass. Glass was chosen for its hardness, strength, durability, and transmittance.
SR glass is textured to create proper traction for vehicles and pedestrians. The glass passed traction tests, load tests, and impact resistance tests at university civil engineering labs around the country.

Each unit is made of top and bottom glass panels, with the other components such as solar cells and LED lights enclosed between. One major difference one will notice when comparing SR glass panels to traditional asphalt roads is aesthetics. The hexagonal panels are quite a work of art and will dramatically beautify roads, parking lots, walkways, patios, bike paths, etc.

Solar Roadways® chose the hexagonal shape for extra stability to wear and flexibility in installing curves, hills, and odd shaped installations. There are half and quarter panel shapes as well. Eventually, other shapes will be added to the SR catalogue of options.
Unlike asphalt, SR panels are impervious to potholes. The repair of potholes is an enormous expense, source of danger and an unnecessary inconvenience to motorists.

Weight Limits

The glass has undergone both 3D Finite Element Method analysis and actual physical load testing at civil engineering labs. The results showed that Solar Roadways can handle trucks up to 250,000lbs (113,398kg). Originally, it was thought that Solar Roadways® panels would need to support only about 80,000lbs (36,287kg), the maximum legal limit for a semi-truck. Upon further research, it became apparent that since logging trucks have no scales in the woods, that can be exceeded. The goal was then adjusted to 150,000lbs. It was subsequently learned that oil companies can get permission to move refinery equipment up to 230,000lbs on frozen roads, so the goal was increased to 250,000lbs.

Some have asked if the current limit of 250,000lbs would support a tank. The current M1A2 Abrams tank weighs about 68 tons, or 136,000lbs, which is well within the current limit.

Hardness

The scale to measure the hardness of materials is called the Mohs hardness scale. It refers to the resistance of a material to being scratched. It lists materials from the softest to the hardest e.g., on a 1 to 10 scale, with talc earning a 1 and diamond, (the hardest common material) being 10.

Asphalt has a hardness of 1.3, copper has a hardness of 3, iron and nickel have a hardness of 4, and steel falls between 4 and 4.5. As you move up the scale closer to diamond, you finally come to glass, which has a hardness of 5.5-6.0.

Strength

When glass is tempered it becomes four to five times stronger than the non-tempered annealed glass listed in Mohs hardness scale. Tempering does not make the glass harder - just stronger. Bulletproof and bomb (blast) resistant glass is made with tempered glass. Solar Roadway® Panels are manufactured in a similar manner. Tempered glass is less likely to experience a thermal break.

Texture/Traction

One of the many technical specs required for SR panels is for a glass surface textured to provide the same or greater traction than current asphalt roads offer (at a minimum) - even in the rain. A variety of textures were tested with a British Pendulum Skid Resistance Tester. Some did not provide enough traction, and one had such an aggressive texture it broke off a piece of the tester. The SR2 texture used was a midrange texture. The final testing results showed the texture was sufficient to stop a vehicle going 80mph (129kph) on a wet surface in the required distance. The test results apply to motorcycles and bicycles as well. New textures will be tested, and the long term goal is to have a whole catalog of textures available to perfectly match each application. For example, highways will require the most robust texture. Applications that are primarily used by pedestrians such as sidewalks and plazas will want a less aggressive texture.

Currently, SR panels can be made with two different types of surfaces:

  1. Non-critical: a walking/low speed driving surface that is capable of stopping a car going 40-mph on a wet surface in the required distance
  2. Critical: a high-speed surface was designed for highway use and can stop a car going 80mph on a wet surface.
The walking surface can be used on sidewalks, bike paths, driveways, parking lots, etc. The high speed surface was used on the SR2 prototype parking lot. It was designed for high-speed roads, but can also be chosen for parking lots and driveways if desired.

Longevity and Durability

SR panels have been designed to last a minimum of 20 years. The advanced loading test that will be performed during Phase IIB will simulate many years of truck abuse in a matter of months. Environmental testing will also be performed. All of this will help to maximize the life expectancy of the SR panels. Solar cells are the limiting factor: they can continue to work up to 30 years but they are at the end of their life cycle by then.

The hexagonal shape was chosen so that any force from vehicles (such as during a collision) is distributed to multiple surrounding panels. The small hexagonal shapes also allow for easier installation on hills and curves.

Repair/ Replacing Damaged Panels

Since the Solar Roadways® system is modular, repair will be much quicker and easier than the current maintenance system for asphalt roads. In the U.S. the time Americans spend idling in traffic costs the nation in a variety of ways.

From the American Automobile Association:
“While many Americans experience congestion on a daily basis, few realize that every hour of congestion, delay, and lack of reliability adds a cost to most services and goods produced or consumed in America.”

Apparently the problem is becoming more serious over time. The new 2015 Urban Mobility Scorecard reports that:
“America’s traffic congestion recession is over. Just as the U.S. economy has regained nearly all of the 9 million jobs lost during the downturn, a new report produced by INRIX and the Texas A&M Transportation Institute (TTI) shows that traffic congestion has returned to pre-recession levels.

According to the 2015 Urban Mobility Scorecard, travel delays due to traffic congestion caused drivers to waste more than 3 billion gallons of fuel and kept travelers stuck in their cars for nearly 7 billion extra hours – 42 hours per rush-hour commuter. The total nationwide price tag: $160 billion, or $960 per commuter.

Washington, D.C. tops the list of gridlock-plagued cities, with 82 hours of delay per commuter, followed by Los Angeles (80 hours), San Francisco (78 hours), New York (74 hours), and San Jose (67 hours).

The problem has become so bad in major urban areas that drivers have to plan more than twice as much travel time as they would need to arrive on time in light traffic just to account for the effects of irregular delays such as bad weather, collisions, and construction zones. For example, drivers on America’s Top 10 worst roads waste on average 84 hours or 3.5 days a year on average in gridlock – twice the national average. Of these roads, six are in Los Angeles, two are in New York and the remaining two are in Chicago. Nine other cities have roads ranked among the 50 worst.”

Each of the SR panels contain their own microprocessor, which communicates wirelessly with surrounding panels. If one of them should become damaged it would stop communicating, and the surrounding panels can report the problem. For instance, "I-95 mile marker 114.3 northbound lane, third panel in, panel number A013C419 not responding".

The panels are light enough that a single operator could load a functioning panel into his/her truck and take it to the location of the damaged panel. The panel could be swapped out and reprogrammed in a few minutes. The damaged panel would then be returned to a repair center.

Potholes are a major source of repair need for asphalt roads and the repair is not nearly as quick or efficient. Potholes in asphalt are formed when moisture accumulates in cracks and breaks in the structure of the asphalt. Temperature fluctuations leading to freezing and thawing then cause expansion and contraction of the material, causing it to weaken. The weight of vehicles contributes to the problem further and eventually a pothole forms. This process cannot happen with SR panels since they are completely impervious to water and therefore potholes will become a thing of the past.

Potholes and other types of road damage can be a danger to drivers, motorcyclists, cyclists, pedestrians, and vehicles. Sometimes potholes are disguised when covered with a puddle of water or ice. Sudden potholes can startle drivers. Some may try to swerve to miss them, which can lead to accidents.

AAA has discussed damages that potholes can do to vehicles. They report that hitting a pothole can knock wheels out of alignment, which then affects steering. A hard impact can dislodge wheel weights, damage tires and wheels, and even suspension components. More about potholes from AAA can be found here.

Hills/Curves/Crowns

People may wonder how SR panels can be installed on hills and curves and how they can accommodate the typical 3% crown that roads have. The very first SR prototype was 12ft x 12ft – it was quickly realized that that size would have made such sites difficult to tackle.

Two important changes were made. The panels were shrunk to about 4ft2 and the shape was changed to hexagons, partially because it was apparent that those changes would make installing on hills and curves so much easier. Roads have what are known as “crowns”: the middle of the road is the highest point so that stormwater doesn’t puddle, but instead runs off of the road. The hexagons easily cover this gentle 3-percent slope.

Eventually, it’s expected that a variety of shapes and sizes will be added to the Solar Roadways® catalog, offering even greater flexibility.

Cleaning

There is also a concern how much a layer of dirt would interfere with solar gain if it did not wash off.
A unique test was conducted during summer drought conditions when the surroundings were covered in dirt/dust. There are two identical traditional (not SR) solar panels positioned on the roof of the original SR lab. For the experiment, only one of them was kept clean and then the outputs were compared.

After one of the panels was cleaned, their performance was monitored throughout a sunny summer day. The clean panel only produced 9% more power than the dirt covered panel. Worst case senario, if it is determined that it is difficult to keep the panels clean, it may only result in a small energy loss. Another consideration is that SR panels, being on the ground, are much easier for homeowners to clean than rooftop panels.

Some anecdotal data was collected with the prototype parking lot: a rubber soled shoe and a bike tire were used to scuff a section of concrete and a section of the SR glass. The rubber on the glass came off with the simple wipe of a finger: it didn't stick well to the glass. That was not the case with the porous concrete: the skid marks were very hard to remove due to the porous nature of concrete.

The supposition is that the simple act of tires rolling over a skid mark on the glass will be enough to loosen the material, which will then blow off or be removed the next time it rains.

It is apparent that most roads with high speed vehicles keep themselves quite clean. Most small particles are blown off by the passing vehicles, with the exception of spills from oil, transmission fluid, etc.

A possible solution for those substances is a common natural compound called titanium dioxide(TiO2). Consultation with a manufacturer revealed that titanium dioxide turns substances like oil and grease into a powder, that would be blown off by wind or washed away by rain. It is currently used on building facades to keep them clean. One manufacturer reported to SR that roads sprayed with titanium dioxide only needs to have it reapplied every few years.

The worst case scenario would be the following: if there is a significant problem with keeping roads clean and all of the above solutions fail, street sweepers may be employed where needed (vehicles with large rotating brushes). They are used in Idaho in the spring to clear the roads of the sand that was used for traction during the winter months.

Disasters

People ask how would a Solar Roadway® glass panel be likely to fair in the event of various disasters?

It’s to be expected that any force that could destroy an asphalt or concrete road (e.g., an earthquake, sinkhole, or landslide) would have a similar result with a Solar Roadway®. Power will not be lost however: only the damaged panels will stop producing, while any nearby panels that are intact would continue to produce power.

Another advantage of Solar Roadways® in regard to such disasters is their ability to double as an early warning system to alert residents of an impending hurricane, tornado, or the like. The road lines could flash in a particular color (to be determined by DOT officials) so that drivers would know to immediately check local weather reports and avoid danger zones.

Similarly, the roads could create detours and redirect residents away from areas of danger, into safe areas. Most lanes of a highway could be repurposed to take drivers to safety, with perhaps one lane continuing to the danger zone for EMS personnel. Solar Roadways® anticipates consultations with earthquake scientists to see if embedded sensors in some SR panels might aid in data collection and prediction.

Solution to the Infrastructure Crisis

The White House website presents a wealth of useful information to help understand the current U.S. infrastructure crisis: “The U.S. lags behind many of its overseas competitors in transportation infrastructure investment. In the most recent World Economic Forum rankings, the U.S. had in less than a decade fallen from 7th to 18th overall in the quality of our roads. 65 percent of America’s major roads are rated in less than good condition, one in four bridges require significant repair or cannot handle today’s traffic, and forty-five percent of Americans lack access to transit.”

They describe the effects of this problem vividly:

“The costs of inadequate infrastructure investment are exhibited all around us. Americans spend 5.5 billion hours in traffic each year, costing families more than $120 billion in extra fuel and lost time. American businesses pay $27 billion a year in extra freight transportation costs, increasing shipping delays and raising prices on everyday products. Underinvestment impacts safety too. There were more than 33,000 traffic fatalities last year alone and roadway conditions are a significant factor in approximately one-third of traffic fatalities. Such fatalities occur disproportionately in rural America, in part because of inadequate road conditions.”

The problem stems from a lack of funding, as state DOTs allotments continue to fall short of the funds needed to build new roads and maintain current roads each year. Supporters write that sometimes their state DOTs have let asphalt roads return to gravel and gravel roads return to dirt, as they just are not able to maintain them.

Some states such as Missouri have begun to think outside the box. MoDOT is exploring the building of a high tech "Road to Tomorrow", which can showcase possibilities for modern infrastructure. They have approached Solar Roadways® about the possibility of using SR panels as part of this project. Consultation is ongoing.

The modular glass panels created by Solar Roadways® can provide a way to have a modular, intelligent, durable, and modern highway system. This system can offset its initial cost over time by the generation of clean renewable energy (link to Solar Energy page here), helping to eliminate many of the described problems. Thousands of American jobs could be created, while Americans work together to create an infrastructure to be proud of. The same can be true for every country as SR moves to respond to interest.

The Numbers


Numerical Calculations – Updated for 2016

People often ask: "Can we really generate enough pollution-free electricity to power our businesses and homes?" The calculations below are presented to answer this very important question.

First, the "givens":

In the 48 contiguous states alone, pavements and other impervious surfaces cover 112,610 square kilometers - an area nearly the size of Ohio - according to research published in the 15 June 2004 issue of Eos, the newsletter of the American Geophysical Union.* It is believed that continuing development adds another quarter of a million acres each year and that typically, two-thirds of the cover is pavements and one-third is building roofs.

Here are some conversions:

112,610 square kilometers equals 43443.54 square miles. The report used data from 2001, so in 2016 (15 x ¼ million acres) an additional 3.75 million acres have been turned into impervious surfaces. That's an additional 5859.38 square miles, so all told, we have 49302.92 square miles of impervious surfaces.

Removing 1/3 for rooftops and that leaves 32,868.61 square miles of roads, parking lots, driveways, playgrounds, bike paths, sidewalks, etc., to work with.

If these impervious surfaces were replaced with Solar Road Panels, how much electricity would we produce?

In labs, solar cell efficiency has exceeded 44-percent, but they're not cost feasible yet. For our calculations, we use commercially available solar panels, which are cost competitive.

The efficiency of 18.5% is commonly available, so for the calculations, the following (conservative) assumptions have been made:

  • Solar cells have an 18.5% efficiency
  • There is an average of only 4 hours of peak daylight hours per day (4 x 365 = 1460 hours per year)

Sunpower offers a 230 Watt solar panel rated at 18.5% efficiency. Its surface area is 13.4 square feet. If the entire 32,868.61 square miles of impervious surfaces were covered with solar collection panels, then:

((32,868.61 mi²) x (5280 ft / mi)²) / (13.4ft²/230W) =
((32,868.61 mi²) x (27,878,400 ft² / mi²)) / (13.4ft²/230W) =
(916,324,257,024 ft²) / (13.4ft²/230W) = 15,727,953,665,337 Watts or over 15.73 Billion Kilowatts

Considering only the average of 4 hours of peak daylight hours (1460 hours per year), this gives: 15.73 Billion Kilowatts x 1460 hours = 22,966 Billion Kilowatt-hours of electricity.

The farther north one lives, the more one has to angle solar panels toward the equator (or more accurately, the sun above the equator) to gain maximum efficiency.

Solar Roadways did some testing at our location in northern Idaho, an hour south of the Canadian border at latitude 48.19 degrees. The farthest northern point in the contiguous 48 states is 49.38 degrees near Lake of the Woods, Minnesota. That's 82 miles farther north than our location. At this northern position (48.19 degrees North), the optimal solar gain angle for solar panels is 72 degrees. By contrast, Brownsville, Texans would want to angle their solar panels at 26 degrees. So southern roads will naturally produce much more electricity than their northern counterparts, as solar intensity maps show.

Unfortunately, we can't angle roads or parking lots. Roads go up and down hills, have banks on curves (going both left and right), and have a typical three percent "crown" (on both sides) to allow stormwater runoff. It's a pretty safe assumption to figure that the national average angle of roads is zero degrees.

We tested two identical solar panels. One was mounted at the recommended 72 degrees. The other one was placed in line with the horizon (zero degrees) to simulate an average road. We installed a monitoring system to track the data 24/7.

Although the tilted solar panel produced more energy as expected (an average of almost 31 percent more than its horizontal counterpart), we discovered a phenomenon that was apparently previously unknown: The horizontal solar panel produced more energy than the tilted panel on certain overcast days. It appears to be similar to getting sunburned on a cloudy day: sunlight is still present, but it is scattered, so the horizontal solar panel is more likely to pick up the scattered photons than the solar panel aimed at the southern horizon.

For fairness, we subtract 31 percent from our totals since we can't angle roads and parking lots:

22,966 Billion Kilowatt-hours x 0.69 = 15,847 Billion Kilowatt-hours

Another finding from our experimentation was that our 1/2-inch textured glass surface reduced the amount of energy produced by solar cells by 11.12-percent (we are experimenting with some changes to improve that number). Subtracting that from the total, we still have 14,085 Billion Kilowatt-hours. And remember: this is the amount of power calculated for a latitude near the Canadian border. The number would be much larger if calculated for the southern states.

While we found no evidence that moonlight or the light from shining stars at night produce energy in solar panels (a common question), we found that headlights did. Although it would be very difficult to measure accurately due to distance, speed, hi/low beams, etc., we found that a small solar panel placed flat on the ground about 10 feet in front of a vehicle with its high beams on produced electricity in otherwise total darkness. So it appears that vehicles driving on the surface at night will be providing a service as well as reaping the benefits.

According to the Energy Information Administration, the United States (all 50) used 3,741 Billion Kilowatt-hours of electricity in 2009 (EIA Electricity Overview, 1949-2009). It's easy to see that Solar Roadways could produce over three times the electricity we currently use in the United States! In fact, just the "lower 48" could produce just about enough electricity to supply the entire world!

Remember that these calculations are made with very conservative numbers using north Idaho as a reference point, which is one of the least favorable latitudes in the U.S. for solar energy collection.

To see the actual measured results of our Phase II research, see Phase II Results.

Greenhouse Gasses

It is estimated that approximately half (different agencies provide different estimates, but the average is about 50-percent) of the greenhouse gases that are causing global warming come from the burning of fossil fuels (primarily coal) to generate electricity. The Solar Roadway therefore has the ability to eliminate half of the greenhouse gases currently being produced.

Another 25-percent comes from vehicle emissions. A Solar Roadway is an electric road that can recharge electric vehicles (EVs) anywhere. We're talking with companies that make mutual induction plates to charge EVs while they're driving (the "receiver" plate gets mounted beneath the EV and the "transmitter" plate is installed in the road). The Solar Roadway could charge the EVs while they're traveling, which would increase their range. With an infrastructure in place that will make EVs finally practical, people would likely start trading in their internal combustion engine vehicles for EVs. Eventually, we'd have eliminated an additional 25-percent of greenhouse gases.

Summary: the Solar Roadway has the ability to cut greenhouse gases by up to 75-percent!

With internal combustion engines now obsolete, our dependency on oil - foreign or domestic - will finally be over with.

Unlike current road systems, a Solar Roadway offsets its cost over time. No more contributing to the climate crisis. No more dependency on fossil fuels. No more power outages (roaming or otherwise). Safer driving conditions. Far less pollution. A new secure highway infrastructure that pays for itself. A decentralized, self-healing, secure power grid.

The real question may be:
What will be the cost if we don't implement the Solar Roadways?

* The report lists the following citation: Vogelmann, J. E., S. M. Howard, L. Yang, C. R. Larson, B. K. Wylie, and N. Van Driel, Completion of the 1990s National Land Cover Data set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources, Photogramm. Eng. Rem. Sens., 67, 650–662, 2001.

Virtually every report we’ve seen that cites impervious surfaces cites this report, even though it was created in 2001. If anyone knows of a more recently published report, we’d like to be able to cite it and include it this Numerical Calculations page.

LED's


Overview

Solar Roadway® panels have embedded LED lights to replace paint to make road lines and signage. In early development, it was quickly realized that creating panels with glass posed a problem: it wouldn’t work to paint road lines over the solar cells, or on glass. But that realization was quickly followed by the solution: since SR panels are would be intelligent, it would be possible to make road lines and signage from embedded LED lights – eliminating the need for paint and the maintenance for keeping up with painted road line marking.

Using LEDs instead of paint opens up a whole new world of options. Road and parking lot lines, verbiage, and signage now become flexible and customizable. With embedded sensors, the intelligent road can use the LEDs to warn drivers of impending danger, such as a large rock in the road. Safety can also be enhanced by making the road lines more visible, especially in dark, foggy, or stormy conditions.


The SR2 model had five colors: white, yellow, red, green, and blue. Those options were certainly sufficient for roadway applications and for functionality. But since the release of SR2, Solar Roadways® has received a steady stream of interest in the decorating options that SR driveways and parking lots can offer. Since there was so much enthusiasm for that feature, options needed to be explored… more colors would provide more choices for various holidays and entertaining. SR3 panels contain RGB LEDs which can create over 16 million different colors.

Traffic Management

The LED lights in Solar Roadway panels can be used in many different ways to create modern traffic management systems. The flexibility of having lights instead of paint creates options never before possible. Because Solar Roadways® are intelligent, they can enhance the safety of citizens. This intelligence is expressed mostly through the LEDs. It’s the way the panels communicate with drivers and pedestrians. Crosswalks will flash and tell drivers to slow down when a pedestrian is present. Highways will warn drivers of wildlife around a curve. Roads will create detours when there is an accident. LEDs can turn red when a firetruck (or EMS vehicle) is leaving its station on a call.


The effect of switching to the modern infrastructure system that Solar Roadways® can provide would be far reaching.

AAA has sent out a call for such a system on their website entitled Making American Stronger. They write:

"America needs a seamless, multi-modal transportation system, a system of tightly-linked roads, bridges, transit systems, freight rail, airports and seaports - continuously flowing, 24/7 system. Although there have been constructive strides made in the areas of HOV/HOT lanes, GPS navigation, intelligent highway design and other technical advances, the nation’s highway system has been starved of funds for decades and remains remarkably antiquated for a world super-power.”

Early Warning System

If there is an impending natural disaster, such as a hurricane, the LED lights in the Solar Roadways® can become the early warning system. The Department of Transportation (DOT), which has awarded SR with three rounds of funding would need to decide the standards. Perhaps the side lines would blink in red, or turn to blue, for example. The public would be educated to know that this signal means there is an impending disaster, and they need to tune in to their local news station for directives.

Countless other options would be available with flexible lines and signage driven by an intelligent infrastructure system.

AAA in their Making America Stronger campaign wrote:

“A safe, efficient and well-funded transportation system is critical to America’s national security and continued economic vitality. America’s roads, bridges and transit systems connect the fields of the heartland to the supermarket shelves, transport workers to their jobs each day, transport a variety of dangerous substances and function as evacuation routes during natural disasters. However, transportation facilities are vulnerable and must be maintained, improved and safeguarded to assure that they provide safe, reliable transportation on a daily basis and fulfill critical national security functions when needed.”

Visibility

Many people have poor vision at night, especially as they get older. LED lights are much easier to see than painted road lines on dark nights. It’s expected that this Solar Roadways® feature will reduce accident rates. Solar Roadlite LED Road Studs™ in the UK have been shown to reduce nighttime accidents 70%, according the company. Solar Roadways® LED lights would provide even more visibility and would be cover much more area, which ought to reduce accidents more that than that.

Road lines are also harder to see during weather events; such as rain or snow. Often in winter conditions, snow completely obscures road lines altogether, even with the best efforts of snow plow drivers. The LED lights combined with heating elements, which keep snow and ice off of the LED lights, will improve visibility in all weather conditions, enhancing the safety of travelers.

Elimination of Road Paint

The paint used for painting road lines is short lived product. Oregon’s DOT says that it’s goal is to repaint all of their road lines every year (although they apparently don’t reach that goal). An article published by the Federal Highway Administration estimated that in the United States alone, approximately $2 billion is spent annually on pavement markings. Inconveniences result too, from traffic delays to complaints of paint getting on vehicles as they drive in areas that have been freshly painted. All such problems could be obsolete with SR panels.

Wildlife

The feature of Solar Roadways’® intelligent panels and LED warning system will offer never before seen protection for large wildlife. While the load sensors cannot detect tiny animals, such as a chipmunk running across the road, they will certainly detect large animals such as deer, and warn drivers, thus lowering wildlife caused collisions.

Solar Roadways® is anxious to help keep humans and animals safer by reducing this problem.

Applications

All potential Solar Roadway applications can utilize the LED lights in a variety of ways. Highways and roads will use the LEDs for all road lines and signage. Sensors embedded in the panels can detect large objects in the road such as deer, and warn the driver to “slow down” to avoid a collision. When accidents do occur, the LEDs can be programmed in real time to quickly create a detour. If an accident is serious and an injured person needs to be quickly transported to the hospital, the LEDs can create a temporary helipad and keep drivers out of the way so a helicopter can land on the road to access the patient.

Cities will appreciate the ability to make crosswalks safer with SR panels. The intelligent panels can sense a pedestrian in the crosswalk and warn the driver to “slow down”. Even if it is a dark night and the person is wearing black clothing, the driver will realize there is an obstacle in the road, and be able to slow down in time. Cities and towns can also use the LED lights for events and celebrations, both to decorate and to create detours and redraw parking configurations as needed. Just as easily, they can revert to the default settings when the event is over.

Business owners will be able to create multiple parking lot configurations. Tighter spaces on busy days, more roomy spaces when there are fewer customers could have many advantages. Handicapped spaces can be created as needed, rather than choosing a set number of dedicated spaces.



Larger spaces for trucks and RVs clearly marked for their convenience will be just as easy as smaller spaces for motorcycles. Some business owners may want to give preferential parking spaces to certain customers: parents with babies, veterans, or EV drivers, for instance. The names of VIP guests can be written where they are meant to park, and reprogrammed upon their departure.

Business owners will also appreciate the ability to match their logo and theme colors on their parking lots and sidewalks. For hotels, that will extend to courtyards, pool surrounds, patios and walking paths. Sports arenas will no doubt want to match their team colors on parking lots and walkways. If a customer chooses to have their logo engraved into the glass panel, the LED colors can be used to enhance that image.

Airports and pilots have described various ways Solar Roadways® panels can be used at airports. The local airport in Sandpoint has expressed interest in modeling for other airports the many advantages of using SR panels. All lines and signage can be created using SR LEDs instead of paint. Pilots have voiced the need to have signage visible from the air. Even in the event that a pilot loses communication with the control tower, the airport would still be able to communicate with the aircraft by writing messages on the tarmac directing the pilot how to proceed. The LEDs would be useful in lighting a clear path for aircraft after landing, as it taxis to the gate. It’s unknown if SR panels could be employed on actual runways, and certification would be required. This interest will be pursued as funding becomes available. Helipads would be able to use the same technology at hospitals and other places.

Schools can use the same technology for playgrounds. Instead of having to choose only a few sports and games on the given playground footprint, they can offer unlimited options to their students. Teachers can create their own educational games for children. Schools can generate clean renewable energy to power their schools, while enhancing children’s education and enjoyment. Parks can use SR panels for their playgrounds and sport courts too.

Bike paths will benefit from the LED lights of SR panels. The lights can provide lines and signage just as for roads. Lanes can be created if desired. At night the lighting will enhance safety for cyclists. If desired, lights can be turned off unless they sense a bike. In that way, a cyclist will be alerted to an oncoming bike when the LEDs turn on ahead of them.

The unlimited LED colors make it easy for homeowners to have unlimited options for decorating for any holiday: red, white and blue for the 4th of July, pink and purple for Valentine’s Day, green for St. Patrick's Day – all at the touch of a button. Families can use the LED lights for events like birthday parties, both to decorate and to direct guests to the proper driveway. Homes with pools reap both additional energy collection and enhance the ambiance with panels installed as pool surrounds. Garden paths with SR panels can be illuminated for beauty and safety. Families may want to use part of their driveway, patio or a dedicated space for a sport court. LEDs will create the lines for various sports and games. Kids can play basketball and then change the court to a dodge ball configuration, or an educational game. Solar Roadways anticipates creating software for a variety of educational and entertaining games too. Children will be able to play, learn, and exercise at the same time.

Across all applications, the aesthetic benefits of the LED light cannot be overstated.

Flexibility

The flexibility of turning LED lights off and on and changing their colors as desired creates options never before knows to drivers and pedestrians. The verbiage and signage options are limited only be the spacing of the LEDs, i.e. high resolution images are not possible, as so many LEDs would be needed that they would cover up the solar cells and stop energy production.

Across all applications, the LED intensity can be increased, decreased, or powered down manually as the customer prefers. When they are on, they automatically adjust to the ambient light. The most intensity is needed in sunlight; the least at night.

The LED lights which were chosen for SR2 panels were not bright enough to be easily seen on sunny days; LEDs of higher intensity were chosen for our new SR3 panels, and that problem has been solved.

The panels have been specifically engineered to extend the life of the LEDs beyond the lifetime of the panels. Another way to extend their life and save energy is to keep lights off when no one is using the panels, be it a road, a bike path or a driveway. Many rural roads for example, may have no cars on them at 3:00 a.m. The lights can then be turned off. But when the road senses a car (via sensors in the panels), the LED lights will illuminate, warning other drivers that there is now an oncoming vehicle. Standards would have to be set, but we envision LED lights illuminating perhaps 1/2 mile ahead and 1/4 mile behind a vehicle.

Light Pollution

Many are concerned about light pollution. The concern is the night sky will be less visible with so many city lights. Since SR panels provide efficient lighting at night (the photosensor will automatically turn them down at night), many municipalities may decide that overhead lights are not needed in some areas. Since Solar Roadways® panels are at the lowest point, beneath the eyes rather than above, it may be that this will reduce light pollution. Testing will reveal the answers.

Conclusion

The described applications for the Solar Roadways® LED lighting system combine to enhance the safety of humans and animals alike. It is hoped that the implementation of SR on a grand scale will lead to lowered accident rates, perhaps even leading to lower auto insurance rates as those statistics become available.

Heating


Overview

Many people are familiar with the difficulties of driving in winter conditions. Roads lack traction due to standing water, snow, slush, ice, etc., causing people to have to drive slowly and cautiously. This makes commutes longer and drastically increases the risk of motor vehicle accidents (MVA). Just in the United States there are over 100,000 injury causing MVAs per year.


Solar Roadways® panels have an integrated heating component. The heating system in Solar Roadways® maintains a temperature above freezing. This keeps the road free of snow and ice. Since more than 70% of the U.S. population lives in snowy regions, this system is crucial to maintain safe road conditions. The implementation of a heated roadway system would also save a significant amount of time in snow removal. The electricity required to run the heating elements will vary from location to location. Every effort has been made to make sure only the minimal amount of energy is expended in keeping snow and ice from accumulating.

For homeowners SR can provide safe and efficient walking and parking surfaces. Shoveling and plowing are time consuming and shoveling can result in injuries. Many homeowners bear the expense of purchasing snow removal equipment or pay others to plow for them. Heated driveways, walkways, paths, patios, etc. would provide safer walking and driving surfaces that require less maintenance. With the implementation of SR, homeowners would be saved from winter inconveniences.

Powering

The electronics in Solar Roadways® are divided into separate systems. Each panel's heating element and LEDs are driven by the grid/storage system, not by the solar cells directly. The solar cells place the harvested energy on the grid/storage system. The systems are independent of one another. This is important because the heaters/LEDs must work at night when the solar cells are incapable of producing power.

The heaters only have to keep the surface warm enough to prevent snow/ice accumulation. The panels will not be heated to the extent of being warm to the touch. This saves energy and therefore capital for the end user.

The amount of power required by the heaters depends on the ambient temperature and the amount of precipitation. The heaters will only be on when they are needed. The heaters automatically engage when there is precipitation or snow drifts. No matter the ambient temperature, the heaters only need to engage when conditions are both below freezing and there is precipitation. The microprocessor has an uplink to a local weather station to predict precipitation events.

For those who live in the northern climates, the implementation of SR provides added safety and eliminates the expense and inconvenience of snow plows, shoveling, and road chemicals. Those in warm climates won't need the heating feature currently, but due to changing weather patterns, all panels are equipped with heating elements at no extra cost.

Animal Safety

Some have expressed a concern that wildlife will want to rest on the road due to its increased temperature. The area in which our SR2 prototype parking lot is located is full of moose, elk, deer, bear, mountain lions, and assorted smaller creatures. There is constant monitoring of our prototype, and there has been no animal activity. The panels never actually feel warm.

Summary

Winter road conditions are quite worrisome. According to the USDOT, the U.S. spends over 2.3 billion dollars on snow and ice control annually. In addition, there are also millions of dollars spent to repair infrastructure damage caused by snow and ice. Poor road conditions are responsible for many accidents that occur. Managing roadways during the winter is also an expensive process, that leaves many states in financial deficit. The heating elements in SR will provide a dependable safety previously unknown to wintery roads. The SR system helps offset its initial cost, counter balancing cost of implementation and use.

Water


Overview

Stormwater contamination has become a major problem. According to the National Resource Defense Council:

“The United States Environmental Protection Agency (EPA) now considers pollution from all diffuse sources, including urban stormwater pollution, to be the most important source of contamination in our nation's waters.”
Toxicants from impervious surfaces contaminate waterways. During a storm event, water washes over all impervious surfaces collecting: debris, sediment, chemicals, nutrients, etc. Each of these causes harm to the environment.

Although the science behind this problem has been well established, there are still many barriers to resolving this issue. One major barrier to managing water resources is the cost of updating the current infrastructure. According to the 2013 Report Card for America's Infrastructure, wastewater in the US was graded as a "D", meaning it is one step above failing. They go on to say:

"Capital investment needs for the nation’s wastewater and stormwater systems are estimated to total $298 billion over the next twenty years."

The U.S. Global Change Research Program goes on to discuss the wide array of effects of flooding: human safety, human health, property, economy, ecology, and infrastructure. When stormwater is not appropriately mitigated it can develop into conditions that are no longer safe. In the worst of cases the Environmental Protection Agency (EPA) has to declare the site a “Superfund” site, and they must intervene. The EPA explains the Superfund program as the following:

“EPA’s Superfund program is responsible for cleaning up some of the nation’s most contaminated land and responding to environmental emergencies, oil spills and natural disasters. To protect public health and the environment, the Superfund program focuses on making a visible and lasting difference in communities, ensuring that people can live and work in healthy, vibrant places.”

The Solar Roadways® team got a chance to visit an old Superfund site in Tacoma, Washington. This site was first identified as such in 1983. Since then, great efforts have been made by the EPA and the City of Tacoma to clean up this site. The EPA describes this Superfund site:

“The Commencement Bay Nearshore-Tideflats (CB/NT) Superfund site is located in the City of Tacoma and the Town of Ruston at the southern end of Puget Sound in Washington. The site encompasses an active commercial seaport and includes 12 square miles of shallow water, shoreline, and adjacent land - most of which is highly developed and industrialized.”

During this visit the SR team was able to meet with some of the people working on this site including the City of Tacoma’s own Center for Urban Waters. They explained what a huge issue stormwater is, especially in urban areas. They demonstrated their new methods for mitigating and treating stormwater and wastewater.

Solar Roadways® integrates a stormwater capture system. All contaminants that cover the roadways can be washed away by storm events and collected in a tank below the frost line within the Cable Corridor. From the collection tank, the water can be pumped any direction, to a water treatment facility, or treated on site and released back into the aquifer. Another option for stormwater is treatment and recycling. Even though the resulting water would be non-potable it could still be used for a variety of household or business purposes or for irrigation. Each customer would have to investigate their city's policies for recycled water and decide what program best suits their needs.

Durability and Natural Disasters

This water collection system also helps prevent hydroplaning and flash flooding by giving the water a channel off of the roadway. The underground tanks can also help retain water. In the event of a submersion, the panels remain functional, as they are hermetically sealed. SR panels are more likely to handle the abuse of a storm event than traditional solar panels since they can’t be damaged by wind or hail, and their secure position at ground level should help them to survive hurricanes and tornadoes much better than solar panels up high on places such as roofs.

Summary

Stormwater is a pervasive environmental problem that is not currently being mediated effectively. Implementing the appropriate infrastructure will be a costly but worthy endeavor. SR offers the infrastructure to mitigate stormwater while offering a return on investment. SR is a durable, long lasting solution to help keep waterways cleaner and help to recycle water responsibly.

In the first two SR contracts with the USDOT, one of their requirements was: “It mitigates water runoff through either permeability or designed retention and filtration.” This was accomplished by retaining the stormwater (after filtration) below the frost line where it could then be pumped to any location along the road: for instance, to aquifers, agricultural centers, etc.