Photovoltaics is the direct transformation of sunlight to energy !! 
The term „photovoltaics“ is a composition of the Greek word for light and the name of the physicist Alessandro Volta. It describes the direkt transformation of sunlight into electrical energy via solar cells.
The transformation process is based on the photo effect discovered by Alexander Becquerel in 1839. The photo effect is the freeing of positive and negative charge carriers in fixed bodies by light radiation.

How much energy is created?

The produced amount of energy (kWh) depends on the regional site, the direction of the roof and the angle of the installation.
Basic rule:
For every kWp installed solar energy, an energy amount of 700 – 1.300 kWh per year can be expected.
A 10 kWp-PV-installation (100qm area needed) creates solar energy of 7.000-13.000 kWh.
This is a gross gain in 2007(kWh x 0,4921 €) of  4.000 € - 4400 € per year.

How does photovoltaics work?

The electricity generated by the solar modules from sunlight are feeded into the electrical net.
In addition to a sufficiently large roof or free space, some space for the feeding meter is used. For the installation of a solar cell with a power of  1 kWp, a installation area of  10 qm is needed.
All generated energy is feeded into the electrical net and paid for for a duration of 20 years according to the German Federal law „Erneuerbare Energien Gesetz“  with up to 57,4 Cent/kW. (passed on 19.12.2003)

Remuneration photovoltaics

The state has developed several possibilities to support renewable energy sources.
The cornerstones of a successful financing of a PV installation in Germany are:
EEG – Erneuerbare Energien Gesetz (Renewable Energy Law)
KfW – Financing (Kreditanstalt für Wiederaufbau)
Tax advantages

One time subvention when starting a photovoltaics installation (Access to subvention budgets of different federal states and the Federal Republic)

Top arguments for photovoltaics

The sun is the greatest and safest energy source. It will remain for at least several billion years.
Solar energy is clean and free energy.
Solar energy is used on the spot. There are no transport costs and only few wire losses.
Solar installations are technically fully developed, have a long life duration and are a value improvement for the house.
Solar installations represent life quality and show active environmental awareness for a lively future.
And one further advantage:
The energy for the development of a PV-installation pays for itself after five years. After that, the installation creates pure energy gains without using up further resources or emitting pollutants.