Solar energy means using the energy of sunlight to provide electricity, to heat water, and to heat or cool homes, businesses or industry.
Sunlight is a clean, renewable source of energy. It is a sustainable resource, meaning it doesn't run out, the supply can be maintained.
Coal or gas are not sustainable or renewable: once they are gone, there is none left.
More and more people are wanting to use clean, renewable energy such as solar, wind, geothermal steam, hydro-electricity and others. It is sometimes called 'Green Power'.
How does solar work?
Photovoltaic (PV) solar cells directly convert sunlight into electricity. The simplest cells are used to operate wristwatches and calculators, and more complicated systems are used to light houses. PV cells are combined into modules called arrays, and the number of arrays used determines the amount of electricity produced. For example, a large number of arrays would be needed to generate electricity for a power plant. A power plant can also use a concentrating solar power system where sunlight is focused with mirrors to create a high-intensity heat source to produce steam or mechanical power to run a generator that creates electricity.
Solar water heating systems have two main parts: a solar collector and a storage tank. Generally, the collector is a thin, flat, rectangular box with a transparent cover mounted on the roof, facing the sun. The sun heats an absorber plate in the collector, and this heats the water running through tubes inside the collector. The heated water is pumped or moved by gravity into the storage tank. Solar water heaters can use about two thirds less energy than those of other methods.
Heat from a solar collector can power heating and cooling systems in buildings.
Passive solar heating
Some buildings are designed for passive solar heating, and do not need a solar collector. Basically, passive solar heating is when opportunities are made for the sun to shine into the building to warm it up. The walls and floors are made with materials that absorb and store the sun's heat, and they heat up during the day and release the heat at night. This is called direct gain. In cold places in the northern hemisphere big windows are put in the south side of the building, letting in much sunlight. The inside of the buildings are therefore well lit, further reducing use of electricity. Heating bills can be half the size of those for a building requiring electrical or other heating. Building designs make sure that the longest walls run east to west, to allow more sunlight to enter in winter than in summer, with shades and overhangs to reduce summer heat.
Solar Cookers
Solar cookers can cook just about any food that a conventional oven can. A basic cooker is an insulated box with a glass top. Heat from concentrated sunlight gets trapped in the box and can be used to heat food placed in the box.
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