Best way to have 30kwh of batteries?

Hi all,

Currently have 2 X 9.5kwh of batteries and a gen1 5kw inverter.

We generally use 35-45kwh per day of electricity, so I've ordered 2 X Gen 2 hybrid inverters that would take my max charge to 7.2kw X 4hrs in the agile go window - allowing me to charge just under 30kwh per day.

Now ordering another 9.5kwh battery feels like the easy option, but I've got a niggle about some of the dodgy balancing that Givenergy's software does.

What's the gut feel from some of the experts on the forum here? Would having one inverter charging two batteries and then another charging only one cause any issues or am I being overly sensitive to Givenergy's slightly dodgy set up at the moment.

Ultimately I'd get this mysterious EMS device also.

what do you use 45kwh on? there may be better options long term

I thought Plant mode was no longer recommended and until this new magic EMS box comes out? My installer wont install a second AC3 for me due to Plant issues.

But out of interest have your maxed out all possible generation space? While grabing the cheaper energy overnight is great generation is still better. Plus that will be A LOT of bits of GivEnergy kit given the issues people are having lately. Plus the EMS could have other unknown issues once it appears in the wild. Though saying that I will be ordering one as soon as I see them!

hamilton house full of tech, 2 EVs (Tesla and Leaf) etc!

THALL

Well I wouldn't say completely maxed - but I have 18 X 410w panels covering our south facing roof. Have been mulling other spots (eg we have a roof that faces west that could be a non perfect, but additional option).

I'm really thinking about winter months, like now where solar doesn't cut it - as you say if I could have 7p/kw in worst case and zero in best, that feels a pretty nice position to be in!

Agree with your point re Givenergy's general dodginess, but I'm also mulling their general supply chain issues - eg I'm thinking if I order stuff for Jan 31st (when inverters are supposedly finally arriving) then if they still haven't fixed/delivered EMS etc in three months later, I can just cancel and look at competitors...!

alphabeta77 pumping electricity from one battery to another is very inefficient.
I was questioning if your heating is ASHP mainly, Although it may be 200% efficient, fitting a buffer tank and using low-rate electricity to heat a buffer tank can be more cost effective and it does not degrade like a battery will.

alphabeta77 True enough.

With tripple inverters thats 9.7kw output from the batteries, 7.4kw from the solar. 17.1kw potential back into the grid on 100amp fuse? Bet your DNO love you :-)

I am starting to see higher usage too. ASHP, 100% electric home, EV etc. I used 39kw last Sunday, and we are not in the depths of Winter for the heating to be on much. 17kw went directly into the car at the cheaper rate. House battery wasn't fully charged so went from 77% to empty. Only generated 1.5kw solar..... So yeah I do get the higher usage. But if that 45kw is total you could dump grid to car's at cheap rate? It is interesting and worrying watching my home pull 13.5kw from the grid. Zappi 7kw, AC3 battery charge 3kw, ASHP (if on) 3.5kw. Adding a second AC3 so could see 16.5kw over night.....

Yes sorry Thrall, I'll have an end state of two inverters (they'll take away the old gen 1 version on install)

I'll cap export @ 3.6kw, but any export is a fail as far as I'm concerned given you get so little from it!

alphabeta77 As alluded to by @THALL you need to be careful about the load your DNO supply can support. We used to have storage heaters and did blow the DNO fuse with over 20kW of heaters charging overnight. They replaced the old fuse with a 100A one. I think they are BS3161 and can handle 1.5xrated current for some time (hours). I think that the fusible link inside degrades over time hence why our 80A fuse blew after years of punishment. If your DNO fuse is 100A, it could theoretically handle about 24kW, but will likely fail at some point if pushed to that limit. What you could do is install your own 80A fuse between the supply meter and your consumer unit. That way, the DNO fuse should never fail and it'd be up to you to replace the 80A fuse if it did fail.

Our dual hybrids just work. Multiple AC3s don't play nicely. However many hybrids you end up installing (2 or 3), my preference would be to run just one battery off each.

Tim Just to follow this. I did ask about the limit of the 100amp fuse as I was worried how close I am getting to it. The max is 20 something, might be 24kw but the target is to stay under 18.4kw (80%). Random nugget of information.

Yeah, I guess I've been smashing the ol' draw fairly hard given EVs etc, but good shout and I'll check the total draw as could imagine with 2 X EVs @ 7kw chargers and 2 X inverters @ 3.6kw, I'd probably start to see overnight peaks of 21kw in worst case scenarios.

Pretty sure we've already got the fuse setup you describe, but will check!

Good advice Tim - ok will lean towards 1:1 inverter to battery then!