Environment Minnesota Research & Policy Center
America has virtually limitless potential to tap the energy of the sun. Solar energy is clean, safe, proven and available everywhere, and the price of many solar energy technologies is declining rapidly. By adopting solar energy on a broad scale, the nation can address our biggest energy challenges – our dependence on fossil fuels and the need to address global warming – while also boosting our economy.
America has the potential to obtain a large and increasing share of our energy from the sun. In the near term, America should set the ambitious goal of obtaining 10 percent or more of our total energy consumption from the sun by 2030, using a wide variety of technologies and tools. Achieving that target would result in the sun providing us with more energy than we currently produce at nuclear power plants, more than half as much as we currently consume in our cars and light trucks, or nearly half as much as we currently obtain from burning coal.
A comprehensive suite of public policy strategies can remove many of the common barriers to solar energy development and help to make this vision a reality.
There are many ways to take advantage of the sun’s energy. Solar energy can be converted to electricity, or used for lighting, heating and cooling. It can replace the fossil fuels we burn at electric power plants, in factories, in our homes, and even in our cars. Solar energy technologies include:
- Photovoltaics (PV) – Photovoltaics directly convert solar radiation into electricity. PV can take the form of panels or be incorporated into building materials. PV is scalable, generates electricity anywhere the sun shines, including in cold climates, has no essential moving parts, uses virtually no water, and is one of the few power generation technologies well suited for use in urban areas.
- Concentrating Solar Power (CSP) – CSP plants use mirrors to focus the sun’s energy to harness heat that can be used directly or to generate electricity. Because heat is cheaper and easier to store than electricity, CSP plants with thermal storage can be designed to provide energy from the sun even at night. CSP plants have been reliably generating power in desert areas of the West for decades and are now experiencing a resurgence due in part to falling costs and increasing demand for utility-scale renewable electricity.
- Solar water heaters – Rooftop-mounted collectors capture solar energy as heat and produce hot water. Solar heat collectors can be extremely efficient; low-temperature heaters can capture up to 87 percent of the solar energy that reaches them. Solar water heaters can also be adapted for uses ranging from residential water heating to large-scale industrial use.
- Solar space heating and cooling – Collectors similar to those used for hot water can also be used to heat air in place of furnaces or boilers. These systems can contribute 50 percent or more of the energy needed to heat a building. Solar energy can even be used to cool buildings through the use of absorption chillers.
- Passive solar design – For centuries, skilled builders have designed homes and other buildings that take the best possible advantage of solar energy. “Passive” solar design can contribute to the overall efficiency of a building, reducing the need for energy for lighting, heating and cooling.
Solar energy can help power virtually every aspect of America’s economy.
- New homes can be built to maximize use of the sun’s energy through passive solar design and the use of solar PV panels and water heating systems. Solar energy can be paired with advanced energy efficiency techniques to create zero net energy homes, which produce as much energy as they consume. Zero net energy homes have already been built in parts of the country, are possible in all climates, and often save money for consumers over time.
- Many existing homes can also incorporate solar technologies. Photovoltaic panels can be installed on the roofs of 35-40 percent of homes nationwide, and solar heat collectors on 50 percent of residential roofs.
- Commercial buildings – such as big-box stores, strip malls and office complexes – also have many opportunities to take advantage of solar energy. About 60 to 65 percent of commercial roof space nationwide is suitable for photovoltaics. Large-scale commercial photovoltaic and solar water heating installations are also cheaper per unit of energy than smaller residential installations.
Many businesses present unique opportunities to tap solar energy:
- Walmart’s use of skylights in some its big box stores has cut energy costs by 15 to 20 percent by reducing the need for electric lighting.
- Laundry facilities, hotels, hospitals and even baseball’s Boston Red Sox have adopted solar water heating to reduce their consumption of natural gas for water heating.
- Manufacturing facilities consume vast amounts of energy to create heat, much of it at temperatures that could be supplied by solar water heating systems. Food processors, chemical companies and textile plants are among those that are good candidates for solar energy. For example, a Frito-Lay plant in California uses solar concentrators to provide heat for cooking snack foods. At full capacity, the system replaces as much natural gas as is used by 340 average American homes.
- Solar photovoltaics can provide a large share of the electricity needed to operate a farm and keep harvested crops cool, and are especially useful for pumping water, providing irrigation and meeting other needs in remote areas that aren’t easily reached by the electric grid. Many farms could also take advantage of solar energy for heating greenhouses, ventilating barns or drying crops.
Solar in Transportation
- The development of plug-in vehicles – both plug-in hybrids and fully electric vehicles – will allow renewable energy to play a larger role in powering our transportation system. Toyota, for example, is developing solar charging stations for its Toyota Prius plug-in hybrid vehicle, due on the market in 2011. In addition, America’s vast areas of highways and parking lots could house solar panels.
- New transportation technologies create new opportunities to use solar power. California’s high-speed rail authority has committed to powering the state’s new rail system with renewable energy, while major shipping companies are experimenting with the use of “solar sails” to reduce the environmental impact of shipping.
- Government facilities such as offices, schools and wastewater treatment plants, as well as community institutions such as churches, are often excellent candidates for making use of solar energy.
- New policy tools enable members of a community to work together to finance solar energy installations, enabling even individuals without suitable roofs to take part in expanding solar power.
- Housing developments in Europe and elsewhere have created neighborhood-wide solar district heating systems that reduce fossil fuel consumption for space heating and water heating by 25 percent or more.
Building the Solar Grid
- Concentrating solar power plants can replace coal and other fossil fuels for base load electricity generation.
- Since photovoltaics generate energy best when demand is highest – on hot, sunny summer days – they can reduce the effective peak demand that utilities have to meet, providing stability to the grid, reducing the need for expensive new power plants and transmission lines, and curbing air pollution.
- Photovoltaic cells and solar water heaters distributed on buildings around the country will reduce the amount of energy that needs to flow from central power plants or energy providers to consumers.
- Investing in forms of “smart grid” technologies can expand the amount of electricity the nation can generate from distributed solar power while maintaining reliable electricity supplies.
America can obtain a large share of its energy from the sun. But it will not happen on its own. Local, state and federal governments must implement public policies that remove the barriers currently impeding the spread of solar energy and adopt policies to make solar energy an important part of America’s energy future.
- Financial incentives, such as grants, tax credits and feed-in tariffs help to compensate homeowners and business owners for the benefits their investments in solar energy deliver to society and can create a robust early market for solar technologies, building the economies of scale needed to lower the price of solar energy. To create a stable market, financial incentives should be applied consistently over a long period of time, instead of as intermittent, on-again off-again programs.
- Renewable electricity standards (RES), such as those now in place in 29 states, can ensure that utilities integrate solar into their energy profiles. Solar carve-outs, which require that a share of the RES be met with solar energy, can ensure a diversified mix of renewable resources and encourage the development of distributed renewable resources.
- New financing tools can help individuals and businesses absorb the large upfront costs of solar installations and begin reaping benefits immediately. Municipalities can use their power to borrow at low interest rates to finance solar installations, which can be paid back through assessments on property tax bills. Utility on-bill financing can achieve similar aims, while low-interest loans and loan guarantees can help reduce the payback time for solar energy investments by businesses.
- Advanced building codes and standards can ensure that builders take maximum advantage of passive solar heating and lighting in new buildings and create new opportunities for integrating solar energy into buildings. Solar-ready building standards guarantee that new homes are built with solar energy in mind, and can be broadened to require that solar energy be offered as an option on new homes. Some states and countries have gone so far as to require the use of solar energy (specifically, solar water heating systems) on new residential buildings.
- Consistent rules to ensure access to solar energy are needed to overcome bureaucratic barriers that can prevent individuals and businesses from using solar power. Solar access laws prevent homeowners’ associations and municipalities from adopting rules that effectively ban the use of solar energy, while revisions to permitting rules and utility regulations can reduce the hassle and cost of installing solar energy and ensure that people are compensated fairly for the solar power they supply to the grid.
- Public education and workforce development efforts are critical to expanding the use of solar energy. Public education programs can help answer consumers’ questions about solar energy and make it easier to “go solar.” Workforce training can expand the number of workers with the skills needed to partake in the dramatic growth of America’s solar energy market. Meanwhile, energy labeling requirements for buildings can ensure that the energy-saving value of passive and active solar energy systems is fully understood when properties change hands.
- Investments in a solar grid will be needed to fully tap America’s solar energy potential. A well-designed “smart grid” can ensure that solar power is an asset to the electric grid, while limited investments in new transmission capacity can help to tap the nation’s best solar resources.
- Research and development programs can help ease the integration of existing solar technologies, further develop emerging technologies with great promise for the future, and investigate new potential uses for solar energy.