Photovoltaic systems use no fuel, and modules typically last 25 to 40 years. Thus, capital costs make up most of the cost of solar power. Operations and maintenance costs for new utility-scale solar plants in the US are estimated to be 9 percent of the cost of photovoltaic electricity, and 17 percent of the cost of solar thermal electricity.[71] Governments have created various financial incentives to encourage the use of solar power, such as feed-in tariff programs. Also, Renewable portfolio standards impose a government mandate that utilities generate or acquire a certain percentage of renewable power regardless of increased energy procurement costs. In most states, RPS goals can be achieved by any combination of solar, wind, biomass, landfill gas, ocean, geothermal, municipal solid waste, hydroelectric, hydrogen, or fuel cell technologies.[72]
“[The maps] suggest that our 100 percent renewable energy purchasing goal — which relies on buying surplus renewable energy when it’s sunny and windy, to offset the lack of renewable energy supply in other situations — is an important first step toward achieving a fully carbon-free future,” Michael Terrell, Google’s head of energy markets, wrote in a blog post. “Ultimately, we aspire to source carbon-free energy for our operations in all places, at all times.”
Solar and wind are Intermittent energy sources that supply electricity 10-40% of the time. To compensate for this characteristic, it is common to pair their production with already existing hydroelectricity or natural gas generation. In regions where this isn't available, wind and solar can be paired with significantly more expensive pumped-storage hydroelectricity.

The Desert Sunlight Solar Farm is a 550 MW power plant in Riverside County, California, that uses thin-film CdTe-modules made by First Solar.[41] As of November 2014, the 550 megawatt Topaz Solar Farm was the largest photovoltaic power plant in the world. This was surpassed by the 579 MW Solar Star complex. The current largest photovoltaic power station in the world is Longyangxia Dam Solar Park, in Gonghe County, Qinghai, China.
A photovoltaic system converts light into electrical direct current (DC) by taking advantage of the photoelectric effect.[51] Solar PV has turned into a multi-billion, fast-growing industry, continues to improve its cost-effectiveness, and has the most potential of any renewable technologies together with CSP.[52][53] Concentrated solar power (CSP) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Commercial concentrated solar power plants were first developed in the 1980s. CSP-Stirling has by far the highest efficiency among all solar energy technologies.
Outline of energy Energy Units Conservation of energy Energetics Energy transformation Energy condition Energy transition Energy level Energy system Mass Negative mass Mass–energy equivalence Power Thermodynamics Quantum thermodynamics Laws of thermodynamics Thermodynamic system Thermodynamic state Thermodynamic potential Thermodynamic free energy Irreversible process Thermal reservoir Heat transfer Heat capacity Volume (thermodynamics) Thermodynamic equilibrium Thermal equilibrium Thermodynamic temperature Isolated system Entropy Free entropy Entropic force Negentropy Work Exergy Enthalpy
The typical cost factors for solar power include the costs of the modules, the frame to hold them, wiring, inverters, labour cost, any land that might be required, the grid connection, maintenance and the solar insolation that location will receive. Adjusting for inflation, it cost $96 per watt for a solar module in the mid-1970s. Process improvements and a very large boost in production have brought that figure down to 68 cents per watt in February 2016, according to data from Bloomberg New Energy Finance.[69] Palo Alto California signed a wholesale purchase agreement in 2016 that secured solar power for 3.7 cents per kilowatt-hour. And in sunny Dubai large-scale solar generated electricity sold in 2016 for just 2.99 cents per kilowatt-hour – "competitive with any form of fossil-based electricity — and cheaper than most."[70]
“University of Texas Study Highlights Wind’s Low Cost” • Wind, solar and natural gas have the lowest levelized cost of electricity in the majority of counties across the United States, according to a new report from The University of Texas at Austin’s Energy Institute, part of a series of white papers on the Full Cost of Electricity. [Into the Wind]
Biomass, biogas and biofuels are burned to produce heat/power and in doing so harm the environment. Pollutants such as sulphurous oxides (SOx), nitrous oxides (NOx), and particulate matter (PM) are produced from the combustion of biomass; the World Health Organisation estimates that 7 million premature deaths are caused each year by air pollution.[77] Biomass combustion is a major contributor.[77][78][79]
“Renewable Energy Market to Garner $2,152 Billion by 2025, Reveals Report” • According to a report published by Allied Market Research, renewables industries will very likely result in an impressive growth for the entire market. It projects the global renewable energy market is to reach in excess of $2,152 billion by 2025. [Interesting Engineering]

Compact Linear Fresnel Reflectors are CSP-plants which use many thin mirror strips instead of parabolic mirrors to concentrate sunlight onto two tubes with working fluid. This has the advantage that flat mirrors can be used which are much cheaper than parabolic mirrors, and that more reflectors can be placed in the same amount of space, allowing more of the available sunlight to be used. Concentrating linear fresnel reflectors can be used in either large or more compact plants.[16][17]
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