Solar energy (Solar) is the energy produced by the continuous fusion reaction process inside the sun, and what we usually call solar energy generally refers to the radiant energy of sunlight, which is generally used in modern times for power generation. Currently, solar energy is used in two ways: passive (photothermal conversion) and photovoltaic conversion. Solar power generation as an emerging way to use renewable energy. People's interest in solar energy can be broadly divided into two categories.
One type is the use of solar photovoltaic panels to make solar cells
The principle of power generation is the "photovoltaic effect". When the sunlight shines on the solar cell, the cell absorbs certain energy photons, resulting in "photogenerated electron-hole" pairs, called 'photogenerated carriers', the two have opposite electrical properties, electrons are negatively charged, holes are positively charged; the opposite electrical properties of The "photogenerated carriers" are separated by the built-in electric field generated by the semiconductor p-n junction, and collected by the positive and negative poles of the solar cell, so that the accumulation of different charges at both ends of the cell, that is, to produce "photogenerated voltage", which is "photovoltaic effect". If the electrodes are led on both sides of the built-in electric field and connected to the load, there will be "photovoltaic current" passing through the load, so as to obtain the output of electricity.
The other type is the use of solar thermal energy aggregation to produce hot water, steam and electricity
Modern solar thermal technology aggregates sunlight and uses its energy to produce hot water, steam, and electricity. In addition to using appropriate technologies to collect solar energy, buildings can also harness the sun's light and heat by incorporating appropriate equipment into their design, such as large south-facing windows or using building materials that absorb and slowly release the sun's heat.
Passive use (solar thermal conversion) is the process of concentrating solar radiation energy by reflection, absorption or other means and converting it to a high enough temperature to effectively meet the requirements of different loads. That is, the solar energy is collected by various collectors and the collected thermal energy is used for human purposes. The most widespread early application of solar energy was to heat water, and today there are millions of solar water heating installations around the world. Solar water heating systems consist of three main parts: collectors, storage devices and loop piping.
