Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as hydroelectricity and biomass, wind and wave power, account for most of the available renewable energy on earth of which only a minuscule fraction of solar energy is used. Solar powered electrical generation relies on heat engines and photovoltaic’s. Solar energy's uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes. To harvest the solar energy, the most common way is to use solar panels. The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year. In 2002, this was more energy in one hour than the world used in one year. Photosynthesis captures approximately 3,000 EJ per year in biomass. The solar energy reaching the surface of the planet is so huge that in one year it amounts to about twice as much as will ever be obtained from all of the Earth's non-renewable resources of coal, oil, natural gas, and mined uranium combined. Solar energy can be harnessed in different levels around the world. Depending on a geographical location, the closer we get to the equator the more "potential" solar energy is available. Applications of solar technology
Solar energy refers primarily to harness solar radiation for practical ends. However, all renewable energies, other than geothermal and tidal, derive their energy from the sun. Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to transform sunlight into useful outputs. Passive solar techniques include selecting materials with favorable thermal properties, creating spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are regarded supply side technologies, while passive solar technologies decrease the need for alternate resources and are generally considered demand side technologies. Solar lighting
In the 20th century, artificial lighting became the main source of interior illumination but daylighting techniques and hybrid solar lighting solutions are ways to decrease energy consumption. Daylighting systems collect and distribute sunlight to provide interior illumination. This passive technology indirectly offsets non-solar energy use by reducing the need for air-conditioning and directly offsets energy use by replacing artificial lighting. Although tough to quantify, the use of natural lighting also offers physiological and psychological benefits compared to artificial lighting. Daylighting design implies careful selection of window types, sizes and orientation; exterior shading devices may be considered as well. Individual features include sawtooth roofs, clerestory windows, light shelves, skylights and light tubes. When daylighting features are properly employed they can reduce lighting-related energy requirements by 25%. An active solar method of providing interior illumination is Hybrid solar lighting. HSL systems collect sunlight using focusing mirrors that track the Sun and use optical fibers to transmit it inside the building to supplement conventional lighting. In single-story applications these systems are able to transmit 50% of the direct sunlight received. Water heating
Solar hot water systems use sunlight to heat water. In low geographical latitudes (below 40 degrees) from 60 to 70% of the domestic hot water use with...