Sorry Badger, I misunderstood. I was only thinking of the HP which is when you need to make lunch etc. But of course one avoids doing that on a red day.
It’s slightly different for me, as I have 4.1Kw of solar on the roof for self consumption and sale of excess. Looking at last years red days and how much I generated on those days, many were bright sunny days. That’s good for me as I can make the most of the solar generation and avoid using grid electricity. We’ve had a few sunny days recently, where I’ve generated about 13KWh, self consumed almost all of it and drawn 5KWh from the grid, with 3.5KWh being between 6am and midnight. About 80% of the peak time draw from the grid is the underfloor heating being on in the morning. I could save a lot by putting it on for a few hours before 6am and then putting it on again after I start to get enough solar. I think that coupled with just using the slow cooker during the day to prep a meal for the evening, I should be able to eliminate most of the daytime draw from the grid. We would then be left with just fridge, freezer and some TV in the evening which doesn’t amount to much. Of course if it’s cloudy during a red day, then the strategy may need modifying with the heating on between midnight and 6am and off all day after that.
Certainly Tempo looks good providing one is a careful manager to get the best out of it.
My only question before I make the change is the 64k dollar question - where is electricity going price-wise?
I am with Engie who have just renewed my three year deal to 0.209c HP and 0.174c HC. This says to me one of two things:
- We have you hooked, now pay! (hoping I do not look too closely) or
- We see electricity taking a big hike and our .20 HP and .17 HCwill be regarded as cheap in two years time, meaning you will have a big win in year three.
Knowing how these people work, I am inclined to think the first one. But, who knows what will happen next year? Will France be forced to follow the UK where there are reports of some tariffs being 51p per unit… 
What says everyone?
Adam
How much did that cost? I’d like to install some solar but not sure of the pay back.
There was, I think 1.5Kw when we bought the house. We basically almost covered the rest of the south facing part of the roof. I think it cost about €6.5K, but that included bringing the existing installation up to normes and also adding extra equipment that allowed us to monitor and control the electricity produced. Since we had it installed, it’s saved us about €850 per year if you add together the self consumption plus what we earn on the surplus. That’s about 7.5 years to break even. Of course, we’re close to exactly south facing and are far south in France which are both positives. Your milage may vary.
Thanks for that. We’re in the Var so well south too and have space to put the panels in (at?) a pretty good aspect. However IMHO the quality of work here across dicipilines , whether you use individuals or companies, is variable and often poor. Who did you get to do the work? A local firm?
You can do it yourself, from buying panels which simply plug directly into an external electricity sockets
To kits which you can install yourself in the garden or on the roof from places like
https://www.monkitsolaire.fr or https://allo.solar.
It is all relatively simple.
Obviously the simpler the installation is for the person paying the installation bill, the more expensive it is per installed kW.
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Yes, we used a local firm, recommended. We also had an éolienne, which the previous owners payed a fortune for, but was completely useless and very noisy. They dismantled this and resold the parts for us, getting a good price and without taking any commission.
Just to add, because it was installed by an accredited installer, we took advantage of the Prime Energié which will pay us back about €1250 over 5 years. So, the real cost was closer to €5.25K in total.
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I must admit, if I had solar installed (and we have a nice south-facing rear roof to do it in France) I’d have an off-grid setup with batteries for storage of daytime overproduction.
More expensive, but works in a power cut.
I too thought of using batteries to store excess and reusing it. The picture unfortunately wasn’t as rosy as many people (including myself) thought.
From what I’ve gleaned, working during a power cut is just about the only benefit you will get. I used 12 months of my production/export/consumption data up to autumn 2022, taken every 15 minutes and simulated what would happen if I put in a battery to store and recoup surplus. From a purely monetary point of view, it was extremely disappointing. For a 4KWh battery, my yearly saving would be around €93. Increasing the battery size doesn’t really get you much more. For a 12KWH battery the yearly saving was around €133.
If what you want is to work in a power cut, then it’s worth it. If you want to recoup your outlay within your lifetime, then it’s not.
I think it’s always better to spend the extra money on either added solar or better insulation or both.
In saying all that, I think the disappointing figure for me may in large part down to the fact that I do have a well insulated modern house and I do use a high percentage of my production because I do think about what to put on when in order to spread the load evenly throughout the day when I do have a lot of solar.
BTW, I used the same data set to simulate whether a move to the Tempo tariff would be worthwhile. That showed that even if I don’t change my consumption pattern during red days (of course, I didn’t during the period the data was collected) then I could save 6% on my electricity bill. While that’s not a lot, it’s better than a poke in the eye with a sharp stick, and if I has a good strategy for what to do on red days, I could save more.
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Does it have to be about recouping the outlay? Non-reliance on the grid might not be a bad thing when it is clear that lack of investment is making the UK grid barely fit for use and things are likely to get worse.
Obviously it depends a lot on where you live, how much power is used and how much you need to pull from the grid during the winter months - realistically you can’t be off grid 365/365 in the UK, or pretty much any of France so even “off grid” systems need to retain the possibility of grid top-up.
Electricity in the UK is currently 125% more expensive than in France - a factor of 2.25x makes rather a big difference to RoI calculations and it’s due to go up in April. The UK also makes much less use of renewable sources than does France, strengthening the argument for Solar.
Mind you I’m glad that power here is not as ridiculous as the UK - currently we’re consuming a frankly scary 80kWh/day, though it hasn’t got much above 2°C outside for the past 48 hours and that’s everything, not just heat.
The trick would be to able to use the battery of one’s electric car in two way mode.
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I’m afraid to check. But I suppose I better 
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That is a fairly accurate conclusion, as things are at December 2022.
Clearly, as electricity costs go up & battery technology becomes cheaper then using your stored solar power when the grid is expensive will become more attractive.
To seriously power your home from stored power for long periods isn’t overly practical, unless you have a lot of batteries. Many home storage solutions are around 10kWh, which would at the time of writing would power my house for less than half a day.
Looking further ahead to a smarter grid…if you are prepared to sell back some of your stored power to the grid when there is a need to “peak shave” high demand spikes then you will be rewarded in a reverse way to a Tempo red day.
A silly example, but to illustrate…
If all 35 million Linkys were able & prepared to supply just 0,5kWh from home batteries &/or EVs during a high demand period that’s 17,5 mWh (17,5 megawatt hours = 17,5 million watt hours), which is not to be sniffed at.
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My system decided to save me some money by throwing the breaker which supplies the heat pump. Very considerate of it. I wondered why it was getting colder in the house without the heating kicking in.
Could do without it doing that if I’m going to leave it on when we’re not here.
As for 80kWh/day - that’s not actually than mad. Energy class C (our official designation) is 90-150kWh/m2/year - the house is 150m2 so that’s between 36kWh/day to 61kWh/day - we’re over that upper limit but, as I said it’s been particularly cold this week so we can probably assume that 80kWh/day is near the maximum and the average over the year would be easily under the max for band C.
Thinking about the “Calculating DPE” thread I have no doubt the “survey” that was done was undoubtedly just a “tick box” exercise but in this case seems to be about right.
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Mine (GSHP) did exactly the same a few days after I started using it again for the first time this winter. Mine is outside in a shed, and I decided to have a look before turning it back on. One of the large condensers for one of the pumps had spontaneously combusted, leaving just metal top and bottom and a pile of ash. Fortunately, I have three separate pumps with three different circuits so could disconnect just the one and keep the other two running. It was a bit disconcerting though that this happened, it could have been a lot more serious.
No, obviously it isn’t for you, but a lot of people are put off investing money if there isn’t any sort of return, and the more people invest in renewables for their properties the better. For me it isn’t either, but I was shocked about just how little a battery would do for me and how increasing the battery size made little difference.
That’s something I am looking at. Not many cars support Vehicle To Grid yet but I expect there will be many more in the coming years. Having such a large battery, coupled with the fact that the surplus can be used for another purpose and the fact that the battery can also be topped up independently may make this much more attractive than a captive battery.
Currently, that’s very true and certainly true for me. My main problem is that during the winter, because I have electric heating via GSHP and electric water heater, these together constitute a large proportion of my electricity demand and I can’t reliably generate enough to satisfy them, even if I had lots of battery storage. If I had an alternative heating source, say a wood burner, then it could possibly be different.
Ouch!
Thankfully all I needed to do was turn the switch back on, possibly did it trying to start the compressor - it seems to draw significant current at that point.
This is a common problem. You need to swap the disjoncteur supplying the GSHP for a “courbe D” which is designed to handle high inrush currents. Your system probably has a standard “courbe C” in place.