I think there is a fixed charge to set the thing up. You then have to pick the size of your virtual storage, it doesn’t just store all your excess. After this you pay €1 per month for every KWh of storage you have chosen and when it’s full, you then get the 10c per KWh for every KWh sent to grid after this. When you need to draw from the grid, it will first come from your virtual battery, at no extra cost, and then when it’s empty, you pay for your electricity as normal.
1 Like
This sounds a very sensible syatem
It does, but unfortunately it doesn’t really seem to work out that well in practice, at least with the data I have, if my simulations are correct. I think it’s possibly a bit of a gimmick.
Thank you for that @hairbear. That seasonality was exactly why I had been wondering what are the limits to battery usefulness in an individual solar system.
How long do the various types of batteries retain their charge? I take it not enough to bridge seasonality gaps and maybe not even much span of days?
I think it would be far better with an EV with vehicle to grid or house power then you use all of your generated power.
I am fortunate that my batteries are from a couple of large UPS’s and were FOC as I removed them saving the company money.
I still see solar thermal as the better option for hot water as they are more efficient in the conversion.
I agree about the vehicle to grid. When I buy an EV, probably at least 3 years from now, I’m going to get one with VTG if I can at a reasonable price. At least that will not just provide the buffer for generated electricity, it’ll also make use of the high peaks in summer.
1 Like
For the virtual storage there are transport costs to consider too. Here is what they replied (translated) when I asked them a few months ago about the project.
It is possible to add virtual storage to a central unit that you have already installed
Concretely, we will have to carry out administrative procedures, including a request to connect your plant to Enedis in virtual storage format.
This service as well as our administrative procedures for setting up are invoiced at 250 euros excluding tax.
You will need, among other things, the following documents:
- The prior declaration of work for your photovoltaic installation
- The advisor for your photovoltaic installation
Setting up virtual storage will require you to leave your current energy supplier to join us. This will be the last step of our process
The cost of our electricity supply is aligned with the EDF regulated sales tariff set by the state. The equivalent power subscription is 5% lower than at EDF.
We rely on the Linky counter, if you are not equipped yet, it will be done for free during the setup process
The kWh returned will be subject to the transport costs and taxes in force. Why ? quite simply because they pass through the ENEDIS network to return, unlike physical battery storage.
The “energy” part, the one that concerns us directly will be free, we will give you back the energy that you have sent to us before. This “free energy” share is the one that increases proportionally the most year after year, so this is what will add value to virtual storage over time.
Our electricity and virtual storage offers are non-binding. As long as you subscribe to the virtual battery service, you benefit from unlimited storage in volume and time (day for night, summer for winter, from one year to the next), there is no there is no reset.
I don’t know how to attach their brochure they sent me, but you can see the transport costs in their calculations, which are rather high
In addition to the above costs, I would have the extra costs of a consuel to sign off my installation since I installed it myself.
I did ask if you had a house in the south of France with PV panels but lived in one in the north (which I don’t) whether you could link the 2 supplies up so you could use southern PV in your northern house via their virtual battery. They said not, but they said other operators allowed it.
I would tend to agree with you hairbear. In summer, I have a constant import of electricity (the blue)
which is about 3-4kWh per day. Mainly from hairdryers, microwaves, kettles and fridges operating overnight. A battery would solve this, but at a cost which is probably not worthwhile.
If I had to do it all again, I would absolutely maximise my array for winter sun, i.e. much steeper angles than they say is optimal. This means I would generate less in summer, but I have too much already, but I would generate more in winter when I don’t have enough.
It is a pity there is the artificial 3kW limit before things get complicated with Enerdis and EDF but it would also be cheaper to just add more panels at different orientations, rather than batteries. And as you and Corona have both said, the car would be the ideal battery storage. Hopefully in a few years when my current car needs replacing this will be solved.
As for hot water, I think I would get a heat pump hot water cylinder before a solar thermal array (like so Edel - Hot Water Air Source Heat Pump | GDHV) which they sell in Leroy Merlin etc. They only consume 700W but I have seen others that only use 400W. I think the installed immersion heater is to lift the temperature occasionally for legionnaires disease But again, I would have to wait until our cylinder needed replacing to justify the costs, but hot water is definitely the main electricity consumer in our house. And I would install a much larger tank. We currently have a 200l tank and the temperature is set to the maximum to store as much thermal energy as possible. So generally we can have 3-4 miserable days before I need to switch it across to EDF electricity as opposed to PV to heat water. So far this year, I haven’t done that since April.
I have self installed 2 air-source heat pumps too, to use as air-conditioning in summer with excess electricity, and in winter as heating to replace the oil burner which hopefully can be removed. I have programmed Home Assistant software https://www.home-assistant.io (which logs all my usage/production) to automatically switch them on if the electricity being sent back to the grid exceeds their consumption which ranges from 400-1200W.
2 Likes
When my tank fails, i gave it a massive fill of white vinegar before I relocated it to break down some of the lime scale, I will change to a heat battery (Sunamp) or by then an EU equivalent. Store at various temps as denoted by the chemistry. 1/3 of the size, very convenient and minimal heat loss compared to a water tank. No legionella risk at it stores heat not water, the water only runs through when requested. Incidentally can also recapture waste heat from your AC or with a different chemistry waste cold when you are on heating.
Yes balmy 3kw max, I intend to do mine off grid with an automatic change over switch if I run low on electricity.
1 Like