Photovoltaic Energy

Solar energy reaching the Earth is received as an electromagnetic radiation which is the basic energy source for live on Earth.

The origin of this energy is inside the Sun, where fusion reactions whereby four atoms of hydrogen become two helium atoms and the remaining atomic mass becomes energy. That is to say, The Sun behaves as a fusion reactor placed 150 millions of kilometres away from the Earth.

To obtain electricity directly from light sun has the name of photovoltaic effect. This phenomenon was discovered by the physicist Antoine Becquerel in 1839. In order to get this, we need a material which absorbs the sun light and transforms the light energy into electric energy, just what photovoltaic cells do.

Thus, Photovoltaic Solar Energy is a direct collection of solar energy to change it into electic energy. This process is based on the application of the photovoltaic effect.

The exploitation of this energy can be carried out by using two electricity production systems. The first one is self-consumption of what has been produced (isolated system), the second one is for injection of electricity in the power supply. Depending on our needs, we could use one system or the other.

Isolated Systems:

Isolated systems are normally used for small consumption, such as cottages or country houses where electricity supply is difficult because of the remoteness of the power station. It is also used in small villages in developing countries which do not have an adequate power supply.

Systems connected to the power supply:

In this type of systems, the total amount of electricity produced is injected in the general power supply and the electricity is sold at a price which depends on the country, amount of power generated and injected and the system itself.

The efficiency of these systems depends on the type of technology that has been used, being the monocrystalline silicon the most efficient (around 13% of commercial cells) followed by polycrystalline silicon and the amorphous technology (ArGa).

The use of this technology is growing very quickly. According to the European Observatory (Eurobserver), in 2007, 1,541.2 MWp of photovoltaic energy (57% more compared to 2006) where installed, which made the total capacity installed in the EU reach 4,689.5 MWp. The attention of the European market has been focused more than ever in systems connected to the power supply, representing 99.5% more than the additional capacity that has just been installed.

Spain is the country with the highest solar photovoltaic power installed, followed by Germany. Regarding solar panels, Germany is currently the second biggest producer of solar photovoltaic energy after Japan, with around 5 millions square kilometres of photovoltaic solar collectors. The sale of photovoltaic panels has grown at an annual speed of 20% in the 90s.

In the following years the biggest challenge is to increase the efficiency of the solar cells, use alternative technology to the cells made of silicon and work for a legislative stability to increase the judicial security of the sector. We must be aware that the Sun, existing for more than 4,000 millions years can provide us with all the energy that we need on Earth in a sustainable and unlimited way. This is a valuable resource we should not waste.

Source: Ecological Research Institute

Power demand tracking in real time and generation structure

Developed by ARI