What are the most cost effective DC batteries that can charge up at 10kW/hr from the grid for say 30-40kW of storage?
And I assume you’d need 2x5kW inverters for that?
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What are the most cost effective DC batteries that can charge up at 10kW/hr from the grid for say 30-40kW of storage?
And I assume you’d need 2x5kW inverters for that?
Seems most cost effective storage solution. I suspect could also be hooked into a Powerwall as the gateway would only see it as another energy source after going through the required inverter?i will read this over a few coffee too, sounds like something i would be interested in doing.
But to make electricity cheap enough to justify replacing a gas boiler with a heatpump there needs to be cheap electricity at least once a day.If there is over production there will be low rates, similar with peak-usage rates. My expectation is Time-of-Use rates ... so anyone with battery / EV can fill up during cheap periods, and avoid use during expensive ones.
I think most likely will be a day time cheap rate - when we have loads of wind and solar producing at same time - quite possibly that will be a negative rate
But to make electricity cheap enough to justify replacing a gas boiler with a heatpump there needs to be cheap electricity at least once a day.
My 2 penneth:
With 10.9kW PV and 2 Powerwalls, I use about 2000 kWh off peak and less than 70 kWh peak in a year. Quite a bit of the peak is down to a SMETS1 meter sucking in power when it shouldn’t.
I’m not advocating Powerwalls above anything else, but they have worked well. I do know one guy who has had lots of trouble with his SE setup; the batteries shut down randomly and the panels do similarly on a sunny day and so on. I have some panels with SE optimisers and SE inverter. No trouble with them at all.
What I will say is generation in summer and winter are two extremes; worst winter day 100 wh, best summer day 65 kWh !!
we aren’t big users, just over 9000 kWh per annum. Adding a Powerwall is pointless as I can go 48 hours on two and adding more PV, if I had space, would benefit winter to a degree but be wasted in summer.
Perhaps one day there will be system where we can deposit it in the grid in summer and claw it back in winter for nowt! Dream on…
A lot depends on panel orientation and shading. I’m surrounded by pretty tall trees that have no effect in summer but cause shade in winter.sounds good but I’d guess the average reasonable size in the UK is more like half that - 5kw solar (3.68 inverter) and maybe 10kwh storage? Even that might be optimistic.
in summer that may still be plenty but would increase the deficit in winter?
A lot depends on panel orientation
There was…. It was called the Tesla Energy Plan !Perhaps one day there will be system where we can deposit it in the grid in summer and claw it back in winter for nowt! Dream on…
Ah, but TEP was a “quid pro quo” arrangement not a freebieThere was…. It was called the Tesla Energy Plan !
But alas - no more.
Pretty much my scenario, 4.66kW solar PV, south facing, 3.68kW hybrid inverter and 5x 2.6kW batteries.sounds good but I’d guess the average reasonable size in the UK is more like half that - 5kw solar (3.68 inverter) and maybe 10kwh storage? Even that might be optimistic.
in summer that may still be plenty but would increase the deficit in winter?
Yes, late last year, Tesla cancelled all orders and have since put the prices up. Of course it wouldn't surprise me if the installers due to "cost of living" have also tacked on some extra to Tesla's increase too.Talking of Powerwalls, I paid £8990 installed last year for Powerwall and gateway. Just been quoted £10990 for an additional Powerwall! Is this typical?
Hi,Pretty much my scenario, 4.66kW solar PV, south facing, 3.68kW hybrid inverter and 5x 2.6kW batteries.
Had it 2 years and every day is a game of roulette, fully charge batteries when forecast is cloudy and see how long it lasts. Some days the sun comes out and I’ll bung on a wash & dry cycle. Other days if it remains dull I’ll just let the batteries charge up as much as they can in the day and see how long it lasts into the evening. The balance is trying not to export too much versus maxing the battery capacity so you don’t run out in the evening before cheap rate kicks back in. We time shift everything so between 80-90% off peak usage, washing, drying, charging etc.. even rads throughout the house overnight to avoid central heating in the morning.
For example, today, battery charged to 82% on IO overnight. Drained down during the day in an empty house. Only 3.9kW of solar today so flat lined house usage and minor charge mid afternoon. Come this evening with a family dinner and multiple appliances turned on the rest got used. We’d run dry by 8pm and were consuming from the grid.
In the summer it’s a different game, if we get to 5 or 6pm on 99% battery we’re sorted through the night. Maybe a 1h top up before the end of IO schedule to cover the window before the sun comes up?
I wouldn’t over think it, I bought 2 batteries originally which was okay but after first winter decided I wanted a few more as they were pretty much drained by midday. Now I can usually last until end of peak time 7-8pm, in the worst case scenario, if I charge fully overnight.
45KW a day on the house? I assume this must be heating and so depends on time of year?Hi,
I think you’ve hit the nail on the head there.
This is the system and modus operandi I am looking to achieve. Without breaking the bank though. The battery storage is the key to saving the most, along with a good off peak plan. That said, if I can save £3,500+ or so a year on my elec bills, I’d be happy to spend up to 10x that as an up front investment.
For my situation; I’m using 19,000kW pa.
4,500 on the car,
14,500 is the house.
Currently that’s £6,650pa all at 35p/kW;
45kW a day house,
7kW a day car.
Currently it isn’t worth me switching to a cheap rate off peak plan, because the house would use more at the expensive on-peak rate, than I’d save charging the car off peak!
Proposed system;
9-11.5kW (generating 7,000pa), 30kW battery storage. (Swapping to Intelligent Octopus)
So new system would be;
7,000kW free from the solar,
4,500kW at 10p for the car
7,500kW at 10p from the batteries or 44p grid at peak (Assuming half at each rate to allow for winter use where I’m 15-30kW short on battery storage).
That could potentially bring my bills down to £2,475 ish per year. Or £206pm. That’s £4,175 pa less. That’s a lot !
Bills could be down to £1,200pa (if I had 40kW - 50kW storage!)
- and Yes I am aware there are a lot of other factors and it’s not that simple !
Problem I have with my quotes so far is the batteries - finding an installer that uses and can get ones that charge up at 10kW/hr and with a decent interface (phone app). And that isn’t adding a massive premium for the system and components.
I recokon that I need batteries that charge at 10kW because the IO plan might not always be there, so might be down to a shorter window in the future. (Just like the TEP vaporised!). Plus the car might be charging at the same time !
What system components have you got and what’s the charging rate of your batteries?
I like the Powerwall and Solar edge systems. Time scales and price are a sight problem though.
Anyone got any other more cost effective battery suggestions? Ones that are easy to manage and can charge at 10kW?
Thanks in advance.