Wind Turbines

How the technology works

Photovoltaic; photo (meaning light) + voltaic (meaning energy)

Over 95% of today’s solar cells consist of the semiconductor material silicon. Semiconductors are materials whose electrical conductivity increases under light or heat.

For the production of solar cells, chemical elements are added to either create an electron surplus (n-conductive layer) or an electron shortage (p-conductive layer) – This process is called “Doping”.

In order to achieve the desired effect, the initial material is normally p-doped lightly and a thin surface layer heavily n-doped. This creates the space charge region required for separating charge carriers.

The front contact is a metallic grid, enabling the sunlight to penetrate into silicon between the contacts. Solar cells are also coated with an anti-reflection coating, serving to protect the cells and to reduce energy losses resulting from reflection. This layer gives the solar cells their typical bluish-black appearance.

When sunlight hits the solar cells the light particles (called photons) induce the formation of pairs of charge carriers, i.e. positive and negative charge carriers.

The electrical field of the space charge region separates these charge carriers. The electrons are accelerated to the negative electrode on the front surface and the positive charge carriers to the rear side electrode in the opposite direction.

The electron surplus in the n-silicon (negative electrode) and the electron shortage in the p-silicon (positive electrode) create an electrical voltage between the metal contacts on the front and rear side. For crystalline silicon cells, the electrical voltage at maximum power output is approx. 0.5V.

The electricity produced is direct current (DC) and requires an inverter to enable the power to be used for domestic and commercial appliances.

When the system is producing energy, the electricity is used by any appliances requiring energy, such as lights, TV, fridge, freezer, or any other electrical items. This reduces the need to import energy from the National Grid, and saves you money.

When the photovoltaic system is not producing energy, electricity is imported from the National Grid as normal – you will never be without electricity.

In the event of the photovoltaic system producing more electricity than is being used on-site, surplus energy is exported to the National Grid.

All enquiries   tel: 0844 800 3353   email:
The Solar Trade Association