Solar power is the most abundant, widely distributed energy resource on earth. 

• What solar is and how it works
  Solar energy is heat and light from the sun. Every hour more energy strikes the surface of the Earth than is consumed globally in a year. Like most renewables, solar power emits no greenhouse gases, air pollution or hazardous waste. Solar panels can be recycled.
  
  Solar is a very diverse resource. It can be used directly, such as in passive solar buildings (large, south-facing windows with overhangs calculated to block excesses of summer sun, and maximize winter sun) or daylighting (techniques that maximize natural light in a building and reduce the need for electrical lighting). These forms of solar are an important part of LEED building standards.
  
  Currently, two main technologies transform solar power into electricity. Photovoltaics (PV) are a thin layer of materials (usually silicon-based) laid over solar panels or solar shingles. PV power is mainly used to provide supplemental power to homes or businesses (some facilities do choose to supply all their own needs and/or go totally off-grid).
  
  Concentrating solar power (CSP) is utility-scale solar. It uses mirrors or other reflective materials to convert sunlight to intense heat that then generates electricity in a steam generator. CSP has been used in utility applications for more than fifteen years, and NREL and DOE are cooperating on making this technology more widespread. 
  
• Benefits of solar
  

  Greater energy independence. For businesses and homeowners, solar installations can substantially reduce dependence on the grid. Using supplemental renewable power for heating and cooling systems, industrial processes, etc. may also qualify for tax credits, depending on the state.
  
  If their state supports net metering, consumers with solar can also sell power back to the grid during times of peak load, such as hot summer days.
  
  Off-grid solar applications can also empower rural communities living far from transmission lines. Small solar panels are also ideal for powering irrigation pumps, stock tank pumps, outdoor lighting, etc.

• Challenges for solar
  

  Variability (intermittent). The sun doesn’t shine at night, so solar facilities generate no power during this time. However, they are often helpful in supplying power during times of peak load, such as summertime.
  
  Expensive. Solar currently costs around 40 cents per kilowatt hour, compared to 4-5 cents for wind. The materials for solar panels are not cheap.
  
  However, solar power had recently become the focus of a great deal of research. President Bush has established a Solar Power America initiative, and its goal is to achieve cost-competitiveness for solar technologies across all market sectors by 2015.
  
  Many companies and government labs are looking for cheaper ways to generate solar power, and the price of the technology is dropping as a result.