What is the solar potential in your region? Here are 2 maps of France of average sunshine reflecting the energy potential of solar.
Keywords: solar energies, photovoltaic, thermal, water heater, potential, France, region, kwh / year m2, m².
Here is a more detailed map: DNI solar map of France and some panels and solar photovoltaic products here
1) Average duration of sunshine in hours per year.
Example: if you live in Bas-Rhin (North of Alsace) you will have less than 1750 h of sunshine per year.
2) average energy potential in thermal kwh per year per m2.
Example: if you live in the Bas-Rhin (North of Alsace) you will have less than 1220 kwh of recoverable energy per year.
3) Example with a concrete case: a thermal solar panel mounted in Alsace in the Lower Rhine.
As read on the cards, we have a year:
- less than 1750h of sunshine, take 1500h arbitrarily.
- less than 1220 kwh / m2 of energy, take 1100kwh arbitrarily.
b) Power demand by m2.
So we have an average sunshine power (when the sun is shining) of 1100/1500 = 733W. Which is very correct (the world average is given for 1000W per m2).
For information, the average power over the year calculated over half a day (over the 12 hours of "day") would be 2 * 1100/8766 = 251W.
At these values to obtain the recoverable thermal energy, it is necessary to multiply by the efficiency of the solar panel (assuming that there are no other losses which is generally false) or 70% for thermal and 10% for photovoltaics.
c) Recoverable Energy annually.
Each would bring m2 * 1100 0.7 770 = kWh.
We recall that a liter of petroleum fuel has a calorific value of the order of 10 kWh. Assuming a boiler efficiency of 0.8, one m2 of panel will give the equivalent of 770 / (10 * 0.8) = 96,25L of fuel oil or roughly, taking into account various estimates: 100L per m2 of panel.
Depending on your current fuel consumption, so you can estimate the number of m2 required to fully compensate your oil consumption.
d) Financial "Analysis"
Thus, an Alsatian house that consumed 2500 L of fuel oil will be needed, ideally, 2500/100 = 25m2 of panels (that's a lot, the m2 installed costs on average, with balloon and installation, around 1000 € currently, price excluding aid and subsidies) and will save the equivalent of 2500 * 0.65 = per year € 1625 of fuel oil (this is quite low in comparison to the price of the 25m2 installation which must be located, in 2010 and excluding subsidies, between € 15 and € 20)…
We noted ideally because the reality is not so ideal precisely. Indeed; in winter, solar thermal (due to the rather low heating temperatures reached) only allows to heat domestic hot water or to add heat (before the boiler) to the conventional heating circuit. To switch to 100% solar, you need a low temperature heating floor (or walls).
This is why very few people use solar as heating: the vast majority of installations aim to heat only domestic hot water (which constitutes on average and approximately 10 to 15% of the annual energy consumption ).
Conclusion: difficult profitability, mentalities to change…
This brief calculation shows that the profitability of thermal solar is difficult to achieve for people (the vast majority of us) who do not reason that the financial calculation. Subsidies and various aids, as explained on one page of this site, do not change much… (quite the contrary!)
This will be the case as long as the non-renewable nature of fossil fuels and their induced pollution are not taken into account in their costs or until the ecological aspects come after the financial aspects during a purchase…
The moral aspect (abuses by certain multinationals) should, ideally, also work in favor of the choice of non-fossil fuels ...
Is this not the basis of an econological society and no longer solely petroleum-financial…