Photovoltaics are the wonderful science of generating electricity directly from sunlight.
Light is composed of particles called photons and in 1839 Edmund Becquerel discovered that when photons of light strike two thin layers silicon, which is natural semiconductor, electrons are released and flow from one layer to the other, thus producing electricity.
The stronger the light the more electricity is produced with the peak output in full clear sunshine, however PV arrays still produce useful quantities of electricity in cloudy weather.
With the advent of space travel in the 1950’s millions of dollars was spent in research into the commercial production of PV cells for powering satellites and space stations.
This research has brought the cost of cells down to a level, which makes them financially viable for generating electricity to power domestic properties.
The average PV array for a domestic property will be 10 panels giving a peak power of 1.9 kW covering an area of 12.77 sq m, producing about 1/3 of your annual electrical requirement.
The installation of a PV array is very easy; they are mounted on a suitable south facing roof with no shading from trees or other buildings. The power from the array is produced as low voltage DC that is converted to 230 AC by being fed through an inverter. The output from the inverter is fed via a meter directly into the household electrical system.
The only maintenance that is required is to give the panels an occasional clean to make sure they are not covered with leaves or bird muck.
The panels are guaranteed to give 90% of their rated power for 20 years. They are generally expected to have a life in excess of 40 years.