There will be plenty of days with poor output, that’s when a battery can carry you through, although prices have dropped a lot for batteries may be France didn’t get the memo, or avoid flash sales co and get a local electrician instead.
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With solar power sizing your array correctly is important if you aren’t reselling the power i.e. using it yourself - what is termed as ‘autoconsommation’.
Clearly, if you had a very large array you could probably make a lot of money, but you’d need to balance the capital outlay against the return. As resale only attracts about 0,10€ per kWh these days you are better off using as much of your own produced power yourself as even the cheapest regulated daytime kWh you can get is 60% more than that.
Despite the comments about high battery prices in France I would still consider battery storage as a better option than too many panels.
To give some real world figures… I have a 3kWc array i.e. it’s maximum output is 3kW but apart from very occasional spikes I wouldn’t expect to see more than a maximum of around 2,5 - 2,7kW even in mid summer. Midwinter it can be down to a few hundred watts, briefly. For reference I live in Normandie, & things are better for solar down south.
In 2025 my array produced 2730 kWh.
Of that power 1903 kWh was used directly & 827kWh was exported to the grid for nothing (i.e could have been fed into batteries if I had them).
Our overall electrical consumption was 5759kWh so, given the above PV use, we had to buy in 3856kWh from the grid.
At the cheapest daytime rate we get (Tempo HP @ 0,1612€/kWh) we have saved around 307€. That figure is actually going to be higher as we pay more for daytime power on Tempo white & red days, but blue make up the bulk of the year, & are the default at the highest PV power time of the year.
In order to cover the 3856kWh buy in I’d have to have enough battery storage to provide at least 10kWh per day on average, so actually a lot more given that some winter days would simply not charge things up enough. However, I’d also need a bigger array in order to produce the approx 3000kWh extra production I’d need (given that we waved goodbye to the exported 827kWh anyway).
Now, if I upgrade my van battery to 40kWh I could use the old 24kWh one for the house…
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Is it feasible to charge up the batteries during heures creuses, to be used during the day? That seems to be quite common in the UK for those on EV tariffs.
My problem is trying to work out my demand. We currently run a large b&b, so my consumption is very high, but most is directly related to my business use. We want a heat pump served by solar panels and I think this will demand a battery as our heating needs will be on winter evenings when the sun is not out. It is early days in my planning/prep but I am keen to absorb as much info in my planning. The barn roof is long 30m x 6m so we have ample space. We are in south Sarthe, so not too sunny and hot.
I intend to install PV panels, but it’s not a priority so will only be in 3 or 4 years from now at the earliest. I’m hoping that sodium ion batteries will be commonplace by then, and so will be dirt cheap.
Understandable in France where electricity prices haven’t reached the crazy stupid levels of the UK.
I have a large amount of lead acid batteries from a commercial UPS, about 18kw which being lead acid you can only use about 50% of so 9kw usable. More panels coming to UK but I want to set up a couple in France but cannot be bothered with the arduous paperwork at the moment.
Umm…do you mean that you have enough batteries to power a 9kW load, or that the usable capacity is 9kWh?
Sorry to be pedantic but in the world of electricity details matter.
Registering a PV generator of 3kWc or lower is really easy, so don’t be put off. No visits required.
The biggest thing is ensuring you have the certification that your inverter(s) comply with ENEDIS’s requirements.
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9kw usable Badger. Do you happen to know which inverters are acceptable? Otherwise I’ll use it off grid and run additional cables.
I can see a growing market for stealing EV’s for the batteries
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Some will steal anything.
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So 9kW maximum load then? What capacity have you got?
I have forgotten, get back to you on that one.
What I found with my simulation, using my real generation and consumption figures, the amount you save increases up to about 10kWh of batteries and then after that the extra gain is minimal. But, even with 10kWh batteries I’d only save around € 100 per year. Not worth it for me.
That’s something of a surprise, could you break that down a bit more please?
Well, I have data taken every 15 minutes of power generated, self consumed, consumed from grid and exported. On a spreadsheet, I can convert the consumed power into cost (using standard tarif and tempo), and then add the. standing charge to get a yearly cost. The final figure calculated was very close to the actual cost. Then, knowing when and how much is exported, I can have that power charge a battery (virtually). When the battery is full, then excess is sent to grid as before. When taking power from the grid, I can instead take from the battery if it has power (again, virtually). I then calculate (for several battery sizes) the difference in consumption from the grid with or without battery and how much that saves me. Because I get paid for exporting power I also can calculate the difference in how much I export and how much that lower value costs me. Subtract one from the other and you have how much saving you get.
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Out of interest how much are these small battery inverter packs in France, 2-3kw DJI type?
I am extremely fortunate to be a retired E & I engineer so I bought a bunch of solar panels and inverters from Troostwijk Auctions and installed the system myself. I generate up to 19.2kW per hour - particularly in the current weather - and I installed a 44kWh backup battery. This system provides all the power I need 24/7 and I will be installing two 6kW heat pumps to reduce the need for burning wood over the winter (sometimes a wood fire is nice). The system works very well and the batteries recharge fully even in the winter months.
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And all the power your neighbour would need as well 
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May I enquire about the total cost of the panels, inverters, battery, and all the bits and pieces required to make it work ?
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