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Energy moves the modern world. Available, reliable, affordable energy. Since the
Industrial Revolution, fossil fuels—coal, oil, and natural gas—have powered immense technological progress. But supplies of fossil fuels are limited, and continued reliance on them may have significant environmental consequences.
Fortunately, there are alternatives. The most powerful one is right over our heads. We are bathed in the clean, virtually inexhaustible energy of the sun. Each hour, enough sunlight reaches Earth to meet the world’s energy needs for a year. To harvest this bounty, we need technology that efficiently converts the sun’s energy into forms we can use. Developing this technology is the purpose of the U.S. Department of Energy (DOE) Solar Energy Technologies Program.

Powerful Goals, Powerful Technologies

The Solar Energy Technologies Program is part of the DOE Office of Energy Efficiency and Renewable Energy. The Program’s mission is to improve U.S. security, environmental quality, and economic prosperity through public-private partnerships that bring reliable and affordable solar energy technologies to the marketplace. It supports research and development on a wide range of photovoltaic (PV) and solar thermal technologies that convert sunlight into useful energy.

Photovoltaic Technologies

The majority of the Program’s budget is allocated to PV research and development (R&D). All PV devices convert sunlight directly into electricity. However, there is a variety of materials and processes for creating PV devices, each with its own benefits and drawbacks. The major trade-off is between cost and sunlight-to-electricity conversion efficiency—higher efficiency typically translates into higher cost. Program participants consistently achieve world-record efficiencies for different types of PV, but each effort has the same ultimate goal: optimizing cost and efficiency to produce the least expensive end-use electricity.

Solar Thermal Technologies

The sun’s energy can be put to work in numerous additional ways. Solar thermal technologies provide electricity, hot water, space heating, and lighting. They can be very cost effective—solar water heating is the least expensive form of solar energy—and can even work in tandem with conventional energy sources to improve the flexibility and reliability of the electricity they produce.

A Systems-Driven Approach

The Program uses a “systems-driven approach” to guide and assess its activities. This approach emphasizes the importance of how the many aspects of a technology are related. For example, it considers how changes in a component—such as low-cost polymer frames for solar water heaters—affect an application or market. It also examines how changes in markets modify the requirements for component cost and performance, such as the impact of interconnection standards on the design of power inverters. The systems-driven approach enables the Program to do the following:
• Determine priorities within the Program.
• Identify key market sectors in which solar technologies can have significant impacts.
• Determine critical R&D to address technology barriers related to those markets.
• Develop standardized analyses to ensure that technologies meet cost, performance, and reliability targets.

Working Together

The Solar Energy Technologies Program draws on the capabilities of numerous public- and private-sector partners. DOE national laboratories—the National Renewable Energy Laboratory (NREL), Sandia National Laboratories (SNL), Oak Ridge National Laboratory, and Brookhaven National Laboratory—perform R&D and support program management. To use resources most effectively, cross-cutting teams from these laboratories are organized into virtual laboratories: the National Center for Photovoltaics (NCPV) for PV and Sun Lab for concentrating solar power. U.S. universities perform cutting-edge R&D and nurture the next generation of solar scientists and technologists.
Solar industry partners not only produce innovations, but also ensure that the innovations are transferred to the marketplace.

Looking to the Future

This is an exciting time for solar energy. PV systems are being installed in unprecedented numbers in the United States and worldwide. The first new U.S. concentrating solar power plant in nearly 15 years was completed in 2005, and more plants are planned for the coming years. Other solar thermal technologies continue to make inroads as well.
In 2006, President George W. Bush proposed the Solar America Initiative to accelerate widespread commercialization of solar energy technologies. The goal is to achieve market competitiveness for PV electricity by 2015. It is estimated that, by 2015, the
Initiative will result in deploying 5–10 gig watts of PV (enough to power 1–2 million homes), avoiding 10 million metric tons of annual CO2 emissions, and employing 30,000 new workers in the PV industry. Solar energy is on the verge of becoming a viable part of our nation’s energy supply, but challenges must still be overcome before it is competitive with conventional energy sources. The Solar Energy Technologies Program is committed to meeting these challenges and providing secure, clean energy for the future.