subject: Photovoltaics - The Future Of Electricity [print this page] Photovoltaics are the wonderful science of generating electricity directly from sunlight. 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. Light is composed of particles called photons and in 1839 Edmund Becquere l discovered that when photons of light strike two thin layers of silicon, which is a natural semiconductor, electrons are released and flow from one layer to the other, thus producing electricity.
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 lowered the price of cells down to a reasonable level, which makes them cost effective for electricity generation to power domestic homes.
PV cells 150mm square are built up into panels usually around 1300mm x 1000mm and these panels are built up into arrays to generate the required power. The average PV array for a domestic property will be 10 panels giving a peak power of 1.8 kW covering an area of 13.1 sq m, producing about 1/3 of your annual electrical requirement.
The installation of a PV array is very easy; they are fixed to a suitable south facing roof without shade from buildings or trees. 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. Most manufacturers of panels guarantee that they will give 90% of their rated power for 20 years. They are generally expected to have a life in excess of 40 years.
Now for the finances, in the 1950's a 1.eight kilowat array would have been priced at £1.8m and now it will cost about 10,000. In April 2010 the government are introducing the feed-in tariff system. Your electricity provider will pay you 36.Five pence for every kilowat per hour of electricity you produce whether you use it or not.
A 1.8 kW array will generate 1.6 mW/hrs every year, so you will be paid 584 a year and on top of this you will save 192 by not having to purchase electricity from the national grid, thus giving you a financial benefit gain of £776 a year. This represents a 7.7% return on your investment, which in today's financial climate is very good.
Apart from the financial aspect, generating your own electricity from the sun is immensely satisfying and you will be saving 860kg Co2 per year.
