Optical instrument problems and solar technology

Devices that turn solar energy into heat or electricity are called solar-technology devices, and the science of this field is solar technology (Greek «Helios» – the Sun). Outside the atmosphere the power of solar radiation is about 1360 W/m²; at the Earth’s surface, under a clear sky, up to about 1000 W/m² arrives, depending on latitude, season and time of day. Uzbekistan has many clear days and long summer days, so using the Sun is convenient there. Since ancient times fruit and vegetables have been dried in the sunshine; Abu Ali ibn Sino wrote that a lens collects light into one point and heats it strongly. In the 20th century solar-technology laboratories opened in Tashkent (1934), the «Physics-Sun» scientific-production association was established in 1976, and in 1987 a solar furnace with a thermal power of 1 MW was built at Parkent. A solar collector heats water (Q = cmΔT), while a photocell makes electric current directly from light; in recent years large photovoltaic power stations have also been built in the country. Solar energy is environmentally clean, but depends on weather and time of day.