Solar power

Solar power refers to energy harnessed from the sun and converted to heat or electricity for human use.

As of today, the major part of the energy available to mankind derives from the burning of fossil fuels: coal, oil and natural gas. However, because of increased prices, concern over dwindling fossil fuel resources, and protecting the environment from pollution and the consequences of global warming, there has been renewed interest in “alternate energy” sources in the new millennium. Solar power is one of the most promising alternate sources of energy, because it is renewable, in-exhaustible and available in huge quantities.

How it works

There are many different technologies used to extract energy from sunlight.

1. Photoelectric cells convert sunlight into electricity.
2. Solar panels heat water directly.
3. Stirling engines or steam turbines generate mechanical work from temperature differences. Using parabolic mirrors, temperatures and efficiencies can be increased.
4. Biofuel is essentially sunlight converted into chemical energy with the help of plants' photosynthesis. Like wind and water derived power, this is indirect solar power and not normally referred to as such.

Residential solar power

Roof-top solar panels present the easiest way of providing a house with heat and electricity. Whereas hot water production is economical, electricity production costs more money than does electricity provided by large power plants.

For heat storage, hot water provides good storage capability for several hours or days depending on the size of the installation. Storage over a year is possible but not economical for individual houses.

Electricity is normally stored in accumulator batteries. With their lifetime of only several years, this is only done if no reliable grid-connection is available. With grid-connected houses, solar electricity is generated as direct current at voltages from about 12 V to 800 V and converted to alternating current at the grid voltage, e.g. 230 V. Surplus is automatically fed into the grid and if more power than provided is required, the difference is taken from the grid.