I see this has come up in the past. We have just had a visit from SVH Energie, these guys: http://www.svhenergie.fr/
We live in the Gard, our house faces practically south and the roof has a 30 degree pitch, no shade, but a windy spot (we're in the track of the mistral). The 'study' suggests we should make about 2,450€/year from our panels. They reckon the theoretical annual output (they are prepared to guarantee) is 8,800 kWh/year from a 5.8kW system. The sales people reckoned that was pessimistic, but they would.
The deal costs €27k, but that includes everything (hooking up to EDF, filing all the paperwork, installing, the associated equipment - "ondulateur", some device for optimising performance, etc.) ... the most interesting thing is it includes insurance that covers any shortfall from that figure of 2,450€/year they've promised (including a 2% increase year on year to account for energy price changes). Plus we get the theoretical TVA back at the end of the installation bonus, so we start with about €5k in the bank.
So, in theory (because of included insurance) we cannot make less than €2,450/year. We know we'll pay about €2,820/year (including all insurance, that's for the shortfall insurance and home insurance top-up of about €10/month) and the equipment is all covered.
The panels themselves are SolarWorld, German company but panels made in Grenoble (not China): http://www.solarworld.de/en/home/ ... they have a 30 year guarantee against deterioration of performance (if they deteriorate more than 14% over that 30 years they are replaced for free).
At the end of our 20 year contract with EDF we are told companies can come and take the panels for free (for recycling - they make enough money on the recycling that they don't charge for removal) and it's simple to put the tiles back because the system used makes no modifications to the existing roof.
Now it *seems* they've thought of everything. Sure, I'm not going to get rich with my solar panels, but I shouldn't lose money either - or certainly not very much - because of the guaranteed minimum provided by this included insurance.
What to do....?