Many people confuse photovoltaic solar and solar thermal. Thierry Chaix, Technical Director of the Soleil en Tête network, explains everything about photovoltaics in order to make the right decisions. Interview by Bérangère Larivaud
What is solar photovoltaic used for?
It is used to produce electricity thanks to specific panels in which water does not circulate, as is the case for thermal solar, but electrons. These small electrons placed end to end form a direct current and produce electricity.
What do we do with the electricity we produce with photovoltaic panels?
We can either use it for personal consumption or resell it to EDF. This second possibility is much more attractive financially. Indeed, EDF buys the kWh at 60 cents - 2009 rate - while it pays on average 10 to 12 cents including subscription. The ratio is therefore 5 to 6. EDF offers 20-year contracts during which you sell everything you produce to it.
What are the different existing photovoltaic panel technologies?
The best known photovoltaic technologies are monocrystalline and polycrystalline. The more the cells heat up, the less they produce. Monocrystalline heats more than polycrystalline but its efficiency is higher. We therefore use it rather in the north of France and when we have a small roof area. There is also the amorphous technology, whose yield is half as important as polycrystalline but which makes it possible to avoid temperature losses. It is particularly effective when the sky is cloudy. Finally, new technologies known as "thin layers" are arriving on the photovoltaic market, based on cadium so as to no longer depend solely on silicon as is the case for the first two. But we still have little perspective.
How do you install photovoltaic panels on the roof?
They are either fixed on the existing roof, on the ground or even an independent structure, or they are integrated into the roof. French law recommends this second method in order to obtain better integration from an architectural point of view. You should also know that EDF buys the kWh at 60 cents only if the photovoltaic panels are integrated. Otherwise, the redemption price is only 32 cents.
Can photovoltaic panels be installed on a badly oriented roof?
Yes because orientation has very little impact on production, unlike thermal solar. For example, for a roof facing due east, the loss is only 10% compared to a facing due south. In contrast, the shadow cast - trees, other buildings, etc. - is more detrimental to production. As for the inclination of the roof, it also plays a role. The best inclination is that at 30 °.
Do I need a building permit to install photovoltaic panels?
For an existing building, a building permit is not necessary but a declaration of work must be made. For a new building, it is preferable to integrate the modules in the building permit. There may be special provisions in a municipality concerning the appearance or color of roofs. If you live near a historic monument or in a protected site, the opinion of the Buildings of France may be necessary. Finally, if necessary, you must obtain authorization from your co-owners to perform an installation.
What is the price of photovoltaic panels?
For a power of 3 kWp (kilo watt peak hour), i.e. 20 to 22 m² of monocrystalline panels, 22 to 24 m² of polycrystalline panels, 30 to 35 m² of emerging technology panels or 35 to 40 m² of amorphous panels, it takes about 20,000 € TTC (VAT at 5.5% if the house is more than two years old), including 10% for labor. You benefit from a tax credit of 50% on the equipment. This tax credit capped at € 8,000 for a single person, € 16,000 for a couple, plus € 400 per dependent. What remains to be paid is offset by the income paid by EDF.
Can we obtain aid and subsidies to finance part of our photovoltaic equipment?
Certain regions, departments and municipalities may award grants. It is on a case by case basis. You must obtain information from the Info-Energy areas of the Adème. Some grants can go up to € 3,000, which is a good contribution to finance its equipment.
What can the resale of electricity bring to EDF financially?
For example, for the aforementioned power, an installation will produce approximately 2,700 kWh per year, or € 1,620 per year, at the 2009 tariff. In the south of France, production will be closer to 3,900 kWh per year and will yield 2 € 340.
How long can it take to amortize its photovoltaic panels?
For integrated panels are amortized on average in 6 to 8 years depending on the region. As the contracts with EDF are for 20 years, there remain 12 to 14 years of pure profit. For over-taxed panels, the return on investment is a little longer: 9 to 11 years on average.
Who can we contact to invest in photovoltaic panels?
The Adème Info-Energy areas can guide you. Of course, you can also contact one of the sales outlets of the Soleil en Tête network.
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