Solar energy is the light and radiant heat from the Sun.   Solar power is used as a synonym for solar energy to refer to electricity generated from solar radiation.  Sunlight is used for power or energy in nature and has been harnessed by man for thousands of years.  Solar energy influences the Earth's climate, weather and sustains life.

Sunlight can be converted into electricity using photovoltaics (PV), concentrating solar power (CSP), and other technologies.  PV has mainly been used to power small and medium-sized applications, from the calculator powered by a single solar cell to off-grid homes powered by a photovoltaic array.  Most PV technologies are based on silicon wafer technology mush like those used in the computer chip industry.  Silicon is a highly available resource, though production limitation have held costs high and restricted the growth of PV energy from an economical standpoint.  It is generally anticipated that over the next few years additional output is due to come on line, specifically targeted for the PV industry and prices should decrease. 

New technological innovations such as polymer based PV, thin film and quantum dots should also drive efficiencies.  These new solar technologies will create continued choices for consumers and opportunities for investors.

For large-scale generation, CSP plants like have been the norm but recently multi-megawatt PV plants are becoming common. 2007 marked the completions of a 14 MW power station in Clark County, Nevada and a 20 MW site in Beneixama, Spain.  This is characteristic of the trend toward larger photovoltaic power stations in the US and Europe.

Investing in solar energy companies is a broad term.  It can mean investing in solar energy through purchasing solar power.  It can mean investing in solar energy by adding a solar energy system to your home or business. It can mean investing in solar companies.  This last area is the area we will focus on here at Cleantech Investor.

At cleantech investor we will help you find the best investments in solar energy companies.  By keeping investors up to date with breaking news we can identify the best new investments in solar technologies and also the best investments in solar in general.

The image at left represents incoming solar radiation and the path it takes once it hits the oceans. 

Development, deployment and economics

Beginning with the surge in coal use which accompanied the Industrial Revolution, energy consumption has steadily transitioned from wood and biomass to fossil fuels. The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce. However development of solar technologies stagnated in the early 20th century in the face of the increasing availability, economy, and utility of coal and petroleum.

The 1973 oil embargo and 1979 energy crisis caused a reorganization of energy policies around the world and brought renewed attention to developing solar technologies. Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts included the formation of research facilities in the US (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer Institute for Solar Energy Systems ISE).

Between 1970 and 1983 photovoltaic installations grew rapidly, but falling oil prices in the early 1980s moderated the growth of PV from 1984 to 1996. Since 1997, PV development has accelerated due to supply issues with oil and natural gas, global warming concerns (see Kyoto Protocol), and the improving economic position of PV relative to other energy technologies. Photovoltaic production growth has averaged 40% per year since 2000 and installed capacity reached 10.6 GW at the end of 2007. Since 2006 it has been economical for investors to install photovoltaics for free in return for a long term power purchase agreement. 50% of commercial systems were installed in this manner in 2007 and it is expected that 90% will by 2009. Nellis Air Force Base is receiving photoelectric power for about 2.2 ¢/kWh and grid power for 9 ¢/kWh.

Investing in Solar Technology and Solar Power

Top Solar power Companies by Market Cap

As of mid-April 2009, the top companies by market capitalization in the Solar power industry were:

Investing in solar power technology can be accomplished by investing in solar power companies.  Investment in the solar power industry can come in the form of investments in solar equipment manufacturers, investment in solar suppliers and by investing in the companies that manufacture photovoltaic cells.