Solar power
Solar power is the energy obtained directly from the Sun. Solar radiation on the Earth can be harnessed for its heating capacity or be harnessed with optical or other types of devices. It is a renewable and clean energy, colloquially known as green energy.
The power of the radiation varies depending on the time of day, the atmospheric conditions and latitude. One can suppose that, in good irradiation conditions, the value would be in excess of 1000 W/m² on the surface of the earth. This power is known as irradiance.
Both the direct and diffuse components of radiation or a combination of both can be harnessed. Direct radiation is the radiation that comes directly from the solar source, with no intermediate reflections or refractions. Diffuse radiation is that emitted by the celestial vault thanks to the many solar reflection and refraction phenomena in the atmosphere, clouds and other atmospheric and terrestrial elements. Direct radiation can be reflected and concentrated for use, while diffuse light coming from all directions cannot be concentrated.
According to the Solar Generation IV – 2007 report, entitled "Solar electricity for over one billion people and two million jobs for 2020" by the EPIA (European Photovoltaic Industry Association), it has been calculated that there is more than enough solar radiation in the world to satisfy the demands of all possible installations. The proportion of solar rays reaching the earth’s surface could satisfy global energy consumption more than 10,000 times over. On average, each square metre of the earth is exposed to enough sunlight to receive 1.7 kWh of energy each year.
The average energy received in Europe is around 1,000 kWh per square metre per year; in the Middle East this figure increases to 1,800 kWh. However, unlike conventional sources of energy, the energy cannot be wasted due to a lack of efficiency, because sunlight cannot be wasted.
It is calculated that if 0.71% of the earth’s surface in Europe were to be covered by PV modules, the entire electricity consumption of Europe could be satisfied. In addition, the calculations of the International Energy Agency show that if only 4% of the desert (extremely dry) areas of the world were used for PV installations, the primary energy demands of the entire world could be met. If we take into account the vast areas of unused space (roofs, surfaces of buildings, fallow land, deserts, etc.) the potential is almost endless.
- Every kWh generated with solar photovoltaic energy prevents approximately one kilogram of CO2 emissions into the atmosphere when compared with electricity generated with coal, or approximately 400 grams of CO2 when compared with electricity generated with natural gas.
- A single family home with an installed capacity of 5 kWp on its roof can prevent 1.9 t of CO2 a year, when compared with electricity generated at a natural gas combined cycle plant.
- A 1,200 KWp solar plant, with monitoring and low concentration, can prevent 818t of CO2 per year.
(http://www.epia.org/fileadmin/EPIA_docs/publications/epia/EPIA_SG_IV_final.pdf)
European radiation data for 565 places is published by the European Joint Research Centre (JRC) (http://re.jrc.ec.europa.eu/pvgis/).
