Renewable electricity sources

Renewable electricity

Photovoltaic systems

In years to come, there will not be a single, unique source of electricity, but many renewable electricity sources that will be combined to answer the planet’s electricity needs. Photovoltaic energy and wind energy have in the past 10 years become the dominant form of electricity generation.

With solar cells, it is possible to convert sunlight directly into electricity by the photovoltaic process. When light particles called photons hit the surfaces of a solar cell material (semi-conductor), they transfer their energy to the material’s electrons displacing them from their orbit. If the semi-conductor is doped with suitable impurities then the electrons are attracted to one surface so setting up an electric charge which forms the basis of an electric current.

The principle of a photovoltaic cell

As sunlight is uniformly distributed, this enables every building to have the potential to generate solar electricity locally. The roof is the most convenient place to mount the solar cells if it is correctly orientated to receive solar irradiation.

Typical roof mounted PV panels either side of a set of solar thermal water panels

The potential for generating electricity directly from sunlight is very large and is becoming increasingly cost effective as the technology has improved and the price of electricity generated by conventional sources like fossil fuels is continually increasing.