National Renewable Energy Laboratory Solar Energy Research

Concentrating solar power technology [Photo: National Renewable Energy Laboratory Image Library]
Concentrating solar power technology
[Photo: National Renewable Energy Laboratory Image Library]

The National Renewable Energy Laboratory (NREL) is a federal laboratory "dedicated to the research, development, commercialization and deployment of renewable energy and energy efficiency technologies". NREL conducts research on several types of solar technology:

What are Greenhouse Gases?

The Greenhouse Effect [Image: NOAA Paleoclimatology]
The Greenhouse Effect
[Image: NOAA Paleoclimatology]

Gases in the Earth's atmosphere that trap heat are referred to as "greenhouse gases". Some of these greenhouse gases occur naturally in the atmosphere but are augmented by inputs from human activities. Others are unnatural compounds that are only created and emitted into the atmosphere from human activities. The principal greenhouse gases released into the atmosphere from human activities are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases. The U.S. Environmental Protection Agency inventories greenhouse gas emissions and sinks and provides information about greenhouse gases and climate change.

Solar Energy

Alamosa Photovoltaic Plant, one of the largest photovoltaic plants in the United States. [Photo: National Renewable Energy Laboratory]
Alamosa Photovoltaic Plant, one of the largest photovoltaic plants in the United States.
[Photo: National Renewable Energy Laboratory]

Solar energy technology converts the ubiquitous energy of the sun into electricity through the use of photovoltaic cells and solar-thermal technology, as well as low temperature solar collectors.

Photovoltaic cells use wafers made of silicon or other conductive materials to release electricity when sunlight meets the wafers. These cells are common in household use and at the production-scale of photovoltaic power plants, of which many of the largest are located in Europe. Solar-thermal technology uses mirrors to concentrate the sun's thermal energy and create heat, which can be used to create steam and turn a turbine or drive a heat engine, creating electricity. Low temperature solar collectors simply use the sun's heat energy directly for facility heating purposes, including hot water heating. This type of energy collection can be seen in industrial and commercial facilities as well as residential structures.

Advantages: ubiquitous and renewable
Solar energy is a form of renewable energy that can be made available anywhere on earth as long as there is access to sunlight. It is a "clean" energy source that does not release any greenhouse gases as byproducts.

Disadvantages: cost of production and land use considerations
The incoming energy from the sun exceeds all of the earth's energy needs, but the high manufacturing cost of the materials and technology needed to build solar cells and their relatively low efficiency are challenges that must be overcome in order to take full advantage of solar energy technology. In addition, habitat impacts, ecosystem effects, and land use considerations must be evaluated for large-scale solar development. These effects can usually be ameliorated by proper siting and design.

Tsoutsos, T. , Frantzeskaki, N. and Gekas, V. 2005. Environmental impacts from the solar energy technologies. Energy Policy 33: 289-296.
US Environmental Protection Agency's Clean Energy Program
US Department of Energy: Energy Explained

Photovoltaic Cells

Photovoltaic cells, also known as PV or solar cells, are the medium in which solar energy is converted into electricity. When PV cells absorb some of the photons coming from the sun, electrons migrate to the surface of the cell, and a positive and negative voltage potential is formed. When these voltage potentials are connected, electricity is generated.

An individual PV cell is very small, so many cells are usually connected and placed together in a module. Several modules can then be put together to form an array, which can vary in size and formation, ranging from a cell on a solar powered calculator, to a large scale power production facility that generates electricity which is fed to a regional power grid. Currently, most modules have around a 10% efficiency at converting sunlight into electricity. The electrical current that photovoltaic cells generate is Direct Current (DC) and must be converted to Alternating Current (AC) before it can be used in the electric grid or sold for commercial applications. (Source: US Energy Information Administration).

Environmental Impacts of Solar Energy

Banner of solar power imagery [Image courtesy of U.S. Department of Energy, Energy Efficiency and Renewable Energy, Solar Energy Technologies Program]


The U.S. Environmental Protection Agency lists the following as environmental impacts from solar power:

Air Emissions   Emissions associated with generating electricity from solar technologies are negligible because no fuels are combusted.
Water Resource Use   Photovoltaic systems do not require the use of any water to create electricity. Solar-thermal technologies may tap local water resources if the liquid that is being heated to create steam is water. In this case, the water can be re-used after it has been condensed from steam back into water.
Water Discharges   Solar technologies do not discharge any water while creating electricity.
Solid Waste Generation   Solar-thermal technologies do not produce any substantial amount of solid waste while creating electricity. The production of photovoltaic wafers creates very small amounts of hazardous materials that must be handled properly to avert risk to the environment or to people.
Land Resource Use   Photovoltaic systems require a negligible amount of land area because they are typically placed on existing structures. In contrast, solar-thermal technologies may require a significant amount of land, depending upon the specific solar-thermal technology used. Solar energy installations do not usually damage the land they occupy, but they prevent it from being used for other purposes. In addition, photovoltaic systems can negatively affect wildlife habitat because of the amount of land area the technology requires.

Resources on Effects of Solar Energy on the Environment
Showing 7 Results
ExpandElectricity from Renewable Resources: Status, Prospects, and Impediments
ExpandEnvironmental Impacts of Renewable Energy Technologies
ExpandImplications of Photovoltaic Manufacturing and Production
ExpandIt's Man vs. Bird in a Quest for Power
ExpandReducing the Maladaptive Attractiveness of Solar Panels to Polarotactic Insects
ExpandSolar Energy and the Environment
ExpandSolar Energy Development Programmatic Environmental Impact Statement
Solar Energy Resources
Showing 10 of 57 ( Show All )
The NBII Program is administered by the Biological Informatics Program of the U.S. Geological Survey
About NBII | Accessibility Statement | NBII Disclaimer, Attribution & Privacy Statement | FOIA Logo       USGS Logo       USAgov Logo