Solar Heating Solar Hot Water in Spain
Spain and Portugal are the countries with the most hours of full sunlight in Europe, between 2,500 and 3,000 hours a year, that is, about 8.2 hours a day. It is not surprising, then, that when we look for renewable, unlimited and cheap energy, we automatically think of solar energy. Now, how can we use this incredible source of energy at the domestic level?
There are two methods to benefit from solar energy in our home ; the first uses photovoltaic panels and the second thermal solar panels . We already talked about the difference between the two in this other article , but today we are going to delve a little into its application in heating and hot water production.
Photovoltaic plates, the path to energy autonomy
The photovoltaic panels use the photoelectric effect for electricity from solar radiation. The energy enters them (or rather, it impacts) in the form of solar radiation and leaves it converted into direct current (DC). Then, that current is stored in a battery or a converter transforms it into alternating current (AC) and dumps it into the light box in the house.
Self – generated solar energy can now be used to cover any domestic demand, from the refrigerator to lighting and, of course, also to run our heaters, whether thermoses , boilers or heat pumps . In fact, if our facility is large enough and we have storage media, theoretically we could be energetically autonomous .
Of course, to achieve full autonomy (assuming that is our objective) we will need the heating to work with electricity; otherwise we would continue to depend on gas , diesel or any other fuel. Not only that, also, the technology that we used should be very efficient, or we will inevitably exceed the production of our plates. The electric radiators are then discarded. It is here where aerothermal energy is emerging as the winning bet, since for its operation it only requires a point of light to operate a heat pump , and as we already explained in this post , the consumption of a heat pump is not very high .
Thermal solar panels, heating and domestic hot water
Solar thermal panels use solar radiation to heat a heat transfer fluid or a volume of air that passes through them and which will then transfer its heat to a volume of water contained in an accumulator or inter-accumulator.
The size of the installation, including this tank, will vary depending on the use we want to give to the hot water obtained. If we are going to use it exclusively as drinking water , it is considered that for a house inhabited by four people, two thermal panels (between 3m2 and 4m2) will cover between 60 and 70% of the annual energy needs . As for the size of the inter-accumulator, for a house occupied by two or three people, a 150-liter tank will suffice, while a 250-liter tank will serve five or six people without problems.
On the other hand, if we intend to use thermal solar panels to support heating , the collection surface will depend on the size of the house. As a general rule, it is considered that 1 m2 of panels for every 10 m2 of surface to be heated will result in a reduction of between 20% and 35% in heating costs . Furthermore, we must bear in mind that, for this standard to be met, the emitting system must be of low temperature , that is, underfloor heating , low-temperature radiators , fan coils … The case of underfloor heating is especially interesting for this type of installation, due to its great thermal inertia .
Solar energy: a profitable investment
The legal uncertainty and the high price that solar panels had a few years ago have made even today many people view solar self-generation with skepticism. The truth is that the price of solar energy , like that of all renewable energies, has dropped dramatically in recent years. For example, photovoltaic solar has been reduced by 73% since 2010 and, according to the International Renewable Energy Agency(IRENA) will still fall by half by 2020. In addition, it must be borne in mind that cost is not the only thing that has changed in this time. Technology, both photovoltaic and solar thermal, have improved substantially in the last decade; and of course, that the efficiency increases, the useful life of the panels lengthens and their cost decreases, inevitably having an impact on the amortization period of the investment , which is increasingly shorter.
But what has undoubtedly caused the amortization period to collapse has been the recent repeal of the sun tax . In a recent statement, the Organization of Consumers and Users (OCU) highlighted that with the elimination of obstacles to self-consumption and the recognition of this figure as a consumer right, the amortization period of a solar installation had been reduced to half.
Laws come and go, and no one can guarantee that steps will not be taken in this regard, although it is unlikely in light of what our neighbors in Europe are doing; But what we can be sure of is that the technology for solar self-generation has reached a development in which any investment will pay off quickly. In other words, today, a commitment to solar energy is a guarantee of many years of free energy.