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If we could fully harness all the energy that reaches us from the king of the stars, our supply problems would be solved for ever. As things stand, however, in Spain we use just a tiny fraction of that energy, way too small for a country that is lucky to receive so much sun all year round.

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In his book The Global Solar Economy, the German Hermann Scheer, founder of the European Association for Solar Energy (Eurosolar), condemns the fact that a country with so many hours of sunshine consumes so much imported energy when, with the amount of energy that the sun casts on to Spain, one could meet global energy consumption five times over.

The application of solar energy on a domestic level is slowly becoming a reality. Any home owner can install solar panels according to his needs on to his roof, patio, terrace, fa�ade or windows. These would provide him with all the hot water, heat or electricity that he requires. The two ways of harnessing solar radiation to produce energy are known as thermal solar energy and photovoltaic solar energy. Obtaining heat and electricity is possible with the sun.

Thermal solar energy
The most immediate application of solar energy is thermal, which is based on a principle that anyone can grasp: when the rays of the sun fall on to a surface, it heats up. Thermal collectors, that increase the temperature of water up to 80�C, work like a greenhouse: a type of flat box, covered in glass, catches the heat of the solar energy and keeps it from escaping. This heat is transferred to a fluid - water or air, above all - which in turn carries it to an accumulator.

Thermal solar energy is used, above all, to produce hot water, which in the home is called sanitary hot water, but also to warm up the water of a swimming pool, as well as many other uses outside the domestic scope: purification and desalination plants, agricultural uses, etc.

Lately, vacuum pipe collectors are on the rise. These are capable of reaching temperatures above 100�C, which make them appropriate for uses such as heating and even refrigeration. Although the devices developed so far to generate cold are fairly numerous, more and more innovative manufacturers are coming to the fore. With the added advantage that at precisely the time that air conditioning is needed, the sunnier it is.

Photovoltaic solar energy
There is another type of solar panel, called photovoltaic, that is capable of converting light photons into electricity. Traditionally only isolated properties, far removed from the electric grid, have taken advantage of photovoltaic energy to produce electricity. The panels charge batteries that are then used to power the lightbulbs and household appliances. In this manner, you could switch on the light in the dead of the night even if the sun's given way to the moon. Still, there are now many people in the centre of a town with photovoltaic panels on their roofs. Since September 2000, the law forces the electricity company to pay the user for all the energy that it takes from his network, in exchange for connecting his domestic set up. The cost is 40 euro cents per KWph, way above the normal price of 8 euro cents.

Cost and assistance
There are still some obstacles to overcome before solar energy can compete with traditional energy sources. The most important are the low efficiency of solar systems and the cost of installation. A thermal solar installation to provide enough energy for a four room property costs around 1,200 euros, according to the Institute for Energy Diversification and Storage. This compares favourably with the 9,000 euros that installing a photovoltaic energy system in your home would cost, according to Greenpeace's Solar Guide.

However, the amounts invested pay off in the long run. Installing thermal solar energy, for example, saves you a fortune on your energy bill. If panels replace an electric water heating system, the initial investment will be recuperated in just five years, ten if replacing a gas water heater. The cost of installing a photovoltaic system, will be recuperated in 15 years, according to Greenpeace, thanks to the high income you receive from selling your energy production to the electricity companies. Given that the life of a solar installation is around 20 years, the economic saving is considerable in the long run.

What's more, the environmental quality of solar energy is now rewarded with several grants and subsidies. Both the IDAE and the autonomous communities in Spain give subsidies for the installation of thermal solar collectors, which can reach 70% of the total cost. This has been determined by the Plan for the Promotion of Renewable Energy, passed in 1999. Photovoltaic panels also receive assistance according to the power installed. This is one of the measures with which the Plan for the Promotion of Renewable Energy hopes to achieve one of its final objectives: that renewable energy sources cover at least 12% of Spain's total energy demand by 2010.

DID YOU KNOW�?
- The solar radiation that reaches the planet every year is 200W per square metre, around 3,000 times the global energy consumption. According to Greenpeace, a quarter of Spain's electricity consumption could be produced by simply installing photovoltaic roof panels on existing buildings.

- The installed power of photovoltaic solar energy in Spain is above 12 MWp; 2.8 of which are connected to the network and the rest corresponds to isolated installations. The Plan for the Promotion of Renewable Energy has an objective of 143.7 MWp by 2010.

- In the European Union as a whole, the year 2000 saw over a million square metres of thermal solar panels installed.� Over half of these panels covered roofs in Germany, a country which cannot compete with Spain when it comes to hours of sun.

- If you fancy connecting with the sun, the best option is to contact an authorised dealer who can both give you advice and make all the necessary applications and procedures (including applying for grants).