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Post by annabellespapa on Jan 31, 2023 10:49:37 GMT 1
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Post by Polarengineer on Jan 31, 2023 11:49:21 GMT 1
Battery plus inverter and controls = say€5000. Daytime saving 3600 kWh x €0,15 = €540 (todays kWh rates, when they increase, the day night difference may be the same.) Roi 10years and by then the battery needs replacing. QED. No gain in fact negative due to interest lost on initial investment. Just a guess at the figures and not everything taken into account.
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Post by cernunnos on Jan 31, 2023 12:24:53 GMT 1
I agree with Polar , I did the calculations for our electric use with battery storage and came to the same conclusion , not worth the investment. We are going down a different route , decreasing the use of electric and optimising insulation.
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Post by annabellespapa on Jan 31, 2023 12:24:56 GMT 1
Thanks PE, we have a friend who has recently had solar and batteries installed, they can hold up to 5kw in the batteries either by the solar or night time rate and any excess goes back to the grid for a pittance. What she has noted already is that the batteries are charging during the day, so hence negating the savings and shortening the battery life.
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Post by annabellespapa on Jan 31, 2023 13:02:57 GMT 1
Thanks both, you have just confirmed what I suspected.
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Post by pcpa on Jan 31, 2023 13:18:59 GMT 1
A solar system with battery storage and she is surprised that it is charging during the day? Have I misunderstood something?
You only need to look at how France has 100% successfully hoodwinked the population by making heures creuses less and less cheaper than daytime rates and also penalising those customers by making them pay more for the abonnement which also increases in cost more than the standard tarif and the biggest insult of all is that they have to pay 1ct a unit more for their heures pleines all year round.
Direct Energie who used to be 10% cheaper than tarif bleu now costs more than EDF for HP/HC, they probably want customers to drop it, maybe they are also getting shafted.
Yet EDF are still aggressively selling it as money saving to customers with only a chauff eau to run at night whereas in fact it will cost them dearly.
Anyone thinking of investing thousands on the basis of todays off peak rates in a country which refuses to intervene on the consumer electricity price like France has and where the prices are changing always upwards at the drop of a hat, to purchase equipment that has a finite life and will never show an actual positive return during that time needs their heads examining.
Mind you I said the same about people switching to electric vehicles and expecting to be able to charge quickly and cheaply on journeys outside of the limited home radius.
Solar power for equipment running during the productive hours of daylight like fridges, air conditioning etc is an excellent idea, if you have excess and cheap or existing batteries then why not, my off grid grandfather used WW2 submarine batteries charged from a generator running on TVO, towards the end of the batteries life it was costing him more than having mains connected not to mention the complex manual charging procedure and constant battery maintenance.
Battery prices will continue to fall and their capacity will increase, electricity costs continue to increase for consumers in countrys that still believe in privatisation of the Electricity market, the day will come where battery storage of solar power will be not just viable but essential, it is the electricity suppliers that are driving this but for their benefits not yours, they want to be able to tap into your battery storage including your electric vehicle at times of peak demand.
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Post by cernunnos on Jan 31, 2023 13:50:51 GMT 1
There are soooo many things wrong with buying an electric car . It would be s lot better if more study was put into decreasing the polution and increasing the efficiency of the internal combustion engine. Electric cars are a gimmick and a political solution to the lack of hydrocarbons in Western countries.
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JohnnyD
Member
Mayenne (53) When Covid allows..........Which isn't very often these days........
Posts: 1,973
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Post by JohnnyD on Feb 2, 2023 9:17:49 GMT 1
I know of 2 people who have installed systems like this now, and payback would be in 3-4 years, especially if you have solar panels also, Octopus offer offer a very cheap overnight rate where they charge their batteries, the batteries also charge with excess solar generated, so only draw off the grid at those ludicrous prices when the batteries run low, so i dont think its a simple case of 'this doesnt work'
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Post by beejay on Feb 2, 2023 13:05:09 GMT 1
A solar system with battery storage and she is surprised that it is charging during the day? Have I misunderstood something?
Doesn't she mean that if there is no solar input the batteries will revert to accepting a charge from the mains rather than inputting to it? Or should the system prevent this happening?
I must ask my brother who, last year, paid nothing to the electricity company because his system input more to the grid than it drew from it by virtue of solar panel banks and a very long ground source heat pump system. Not bad for an all electric house that he built from scratch.
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Post by gigi on Feb 2, 2023 13:13:52 GMT 1
Sounds good, beejay. My son, who lives on the south coast, has a system too, paid pence last year; charges the EV each night, and very pleased with the whole thing.
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exile
Member
Massif Central
Posts: 2,670
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Post by exile on Feb 2, 2023 14:08:24 GMT 1
A solar system with battery storage and she is surprised that it is charging during the day? Have I misunderstood something? It is possible that you have. I certainly did but I think I now understand the system. Solar panels charge batteries, any excess is exported to the grid. If the battery charge drops, then it will recharge from the grid. So if you have used a lot of power overnight and the batteries are low, and if the day is overcast, the batteries will charge (from the grid) during the day - as well as taking anything it can from the panels. That last bit (from the grid) was missing from the explanation. Edit to add: This may need a rethink of how to use dual priced energy if you have one of these solar systems installed. Traditionally with dual priced fuel, you use your heavy use item overnight when the power charges are on the low rate. With the addition of solar, you might want to start using your heavy use item towards the end of the higher rate period. You will be drawing down on the batteries but if correctly judged should not need to use grid power. The batteries can then maximise the ow rate power to recharge.
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Post by annabellespapa on Feb 2, 2023 15:55:20 GMT 1
I think the scenario I mentioned was the batteries ignoring they are losing charge during the higher rate electricity and continually topping up the battery store. Maybe if programmed not to or a warning that it is likely to happen might help.
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Post by ForumUser2 on Feb 2, 2023 17:22:06 GMT 1
This is how mine works:
10Kwh battery, 14 400wh solar panels.
Battery charges at 16p/Kwh from 00.30 to 07.30. Battery also charges from the panels. If battery is full excess power sent back to grid at 15p/Kwh.
The battery will not charge from the grid outside the above hours even if it is fully discharged (actually, it never goes below 10% charge to protect the cells).
If panels are producing power at, say, 2kw and we are drawing 3kw then the battery will make up the difference. Only when the battery is discharged and there is no solar power will the system take power from the grid at the daytime rate of 44p/Kwh (Gulp!). This doesn't happen in practice except where the draw is higher than solar plus battery can provide - only when we use the 9.5kwh electric shower
So the hierarchy of use is:
1. Solar 2. Solar plus battery 3. Battery 4. Grid
To put this in perspective our bill has gone from £160pm to about £50. In summer we should be running at a surplus. I reckon we save around £1200 over the year. Could be more depending on how much we sell back in the summer.
Cost £12900 so 10 years to repay at current rates. I can live with that.
Furthermore, the system probably adds at least its cost to the value of the house and drops the EPC to the next lower category.
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Post by lurcher on Feb 2, 2023 18:11:21 GMT 1
Very clear and logical. There will of course be unknown variations in the long term but you must be reasonably satisfied with your choice. Did you buy the solar panels and associated control system direct from your electricity supplier? Also, what happens if panels become faulty?
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Post by annabellespapa on Feb 2, 2023 19:03:16 GMT 1
ForumUser2, thanks for the figures they make good reading, I was considering just a battery bank as the available space for the panels is limited for a 5kwh system, I thought going bigger with the batteries would make the numbers work better but it would appear that when they cover the payback period is when the batteries might need replacing.
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