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  • Writer's pictureΔημήτρης Φλουτσάκος

Photovoltaics on the roof

How you won't pay electricity for 25 years


The "cloudy landscape" in global energy policy and the "puzzles" that consumers are asked to solve, about which electricity tariffs benefit them, are leading more and more people to create autonomous energy systems for their homes.

The most popular, but also as it turns out to be affordable, is the photovoltaic system on the roofs of the houses, for which there was even a subsidized program by the government last year, while in all probability, a new one will be announced.

We spoke with the energy inspector, Michalis Christodoulidis, who deciphered all the elements of such an average system and of course costed us, so that we could determine if the installation of photovoltaics is ultimately worth it and what exactly it offers.

As Mr. Christodoulidis explained to us, "a typical residence, at 100 square meters, has an average annual consumption of 5000 kilowatt hours. This is the current that the photovoltaic system is called to cover.

In order for the electricity produced by the photovoltaic system to be available exclusively to the consumer, without supplying any electricity to the grid, with the autonomy of special batteries-accumulators, a construction must be made that will consist of 5KW (kilowatts), installed power, from 10 panels. These are placed on 20 square meters of unoccupied surface. Each panel has a photovoltaic power of 500W. So the 10 panels will "extract" 5KW of energy, which we need at the time.

"With all the panels installed, cables, inverter, battery, meters and battery and battery charger, panel and together with labor, someone will need to give 12,000-14,000 euros. With the whole package ready to use. We are talking about a fully autonomous photovoltaic installation", says Mr. Christodoulidis.

He also emphasizes that the installation of a 5KW system not only covers the 5 kilowatt hours you need, but you also have a surplus of energy. Such a system makes a house fully autonomous. From then on, the only way out is for system maintenance.

A photovoltaic system on the roof, which will make the residence completely autonomous, covers the owner for 25 years. Then the panels lose their performance over time.

"An average house, a typical household, at 100 square meters, needs about 1000 euros a year, just to pay for electricity consumption. Of course not for the charges that you are not exempt from (municipal taxes, ERT, etc.). In about twelve years, you have therefore made your amortization and for the remaining years you pay nothing for electricity. You are completely independent."

The photovoltaic system can be installed everywhere. But especially for Athens and the big urban centers, Mr. Christodoulidis suggests something else: "In apartment buildings, because there are no roofs available, since the space is covered by solar water heaters, antennas, etc., such a system could be made for the shared electricity consumption. And to be placed at the end of the staircase of the house. From the planning legislation, you can now put photovoltaics with a slope of 3 degrees. However, this must change and go to 30 degrees, since only in this way will there be energy efficiency. 30 degrees is a prerequisite for the basin. Otherwise, this system is not going to work," he says.

The specific system will cover the shared clock of the apartment building. Lighting, elevator, etc. The cost of such a system is 7,000-8,000 euros, for a typical apartment building.


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