How does solar energy convert to heat energy and electricity(I)
Solar energy is radiant energy, have the immediacy, must transform into other forms of energy to use and store. To convert solar energy into different forms of energy require a different energy converters: collector by absorbing solar energy can be converted to thermal energy, photovoltaic solar cells to convert solar energy into electricity, the effect, through photosynthesis, plants can convert solar energy into biomass, and so on. In principle, solar energy can be converted to energy in any form, directly or indirectly, but converting more and eventually lower the efficiency of solar energy conversion.
Solar-thermal energy conversion
Black absorbing surface absorbs solar radiation, can convert solar energy into heat energy, and its absorption capability, but the radiation heat loss, so black absorbing surface is not a perfect solar absorption surface. Selective absorption surfaces with a high ratio of Solar absorptance and lower emission, good capacity of absorption of solar radiation, and radiation heat loss, is more ideal solar absorption surfaces. This absorbing surface by selective absorption material, referred to as selective coating. It was made sometime in the 40 ‘s in 1955 and utility requirements, 70 research into mass production and the selective coating and many new application, has developed hundreds of selective coating.
Electrical energy is a high quality energy, use, transmission and distribution easier. Convert solar energy to electrical energy is important for large-scale use of solar technology, all countries in the world attach great importance to, convert it there are many ways, direct conversion of photoelectric, thermoelectric indirect conversion. Focus on photoelectric conversion devices – solar cells directly.
The world, in 1941, reports of silicon solar cells, developed in 1954 the effectiveness rate of 6% single-crystal silicon solar cell, 1958 applies solar powered satellites. In the 70 ‘s before, due to the low efficiency of the solar cell, the prices are too expensive, is mainly used in space. After 70, solar cell materials, structures and processes have been extensively researched and made more progress in improving efficiency and reducing costs, the ground gradually to expand the scale, but from the large-scale use of solar energy, compared with conventional power generation, the cost remains high.
At present, the laboratory efficiency of solar cells in the world for the highest standard: Mono c-SI 24% (4cm2), SI 18.6% (4cm2), InGaP/GaAs dual junction solar cell 30.28% (AM1), amorphous silicon solar cell 14.5% (the initial), 12.8 (stable), cadmium telluride cells 15.8%, Silicon battery 14.6%, titanium dioxide and organic Nano-cell 10.96%.