I have a gen 3 hybrid inverter with one 9.5kWh battery. If I were to add a second 9.5kWh battery, what would the charge/discharge rate be?
From other discussions, it sounds like the batteries operate in parallel, but would be limited by the inverter, so 5kW?
RyanC yes, 5kW (assuming you have the 5kW inverter, not the smaller 3.6kW one)
I have this system. Actually I’ve got dual Gen3 5.0 hybrid inverters with 2x 9.5’s on each inverter.
It’s limited to the inverters DC charging output rate.
This is what I get (or used to until it started mis-behaving! Recently)
3.7kW when discharging to the home.
4.0kW when discharging using “timed export”.
Charging is;
3.3/3.4 initially then it goes to 3.5 later on during the charge.
So fits quite nicely into IOG’s 6 hour off peak period.
The 5kW on the label is the max it can convert to AC at a time.
But it can convert 5kW to AC while also adding any extra DC from the panels to the batteries at a max of 2.5kW, so if you have an oversized array you can benefit from the extra panel output (as long you have space in the batteries!)
TX200 yes, 5kW (assuming you have the 5kW inverter, not the smaller 3.6kW one)
5kW is a misleading answer, as @Pete UK points out, the 5kW is the max DC that the inverter can convert to AC.
To answer @RyanC ’s original question, adding a second battery will give you exactly the same battery discharge and charge rate as the inverter already has, which for a Gen 3 hybrid is a nominal 3.6kW, NOT 5kW. I practice you can get a bit more than the 3.6 when discharging and a bit less when charging.
The batteries operate in parallel so you will extend your storage but not the charge/discharge rate.
And be aware that you won’t get 100% usable extra storage. It seems that with multiple connected batteries when one reaches 100% full or 4% empty then they BOTH stop charging or discharging. The SoC tends to drift apart on th two batteries by about 10-15% so you won’t quite get doubling your capacity when adding a second battery.
I’d advise doing the maths of whether its worthwhile or not. Depends on your tariff and what you want to use the extra storage for. I came up with payback periods of 5 to 22 years depending on different strategies!
geoffreycoan I keep forgetting about the AC charge/discharge limit.
Datasheet is here @RyanC
https://givenergy.co.uk/wp-content/uploads/UK-Datasheet-Hybrid-Gen-3-5.0.pdf
geoffreycoan And be aware that you won’t get 100% usable extra storage. It seems that with multiple connected batteries when one reaches 100% full or 4% empty then they BOTH stop charging or discharging. The SoC tends to drift apart on th two batteries by about 10-15% so you won’t quite get doubling your capacity when adding a second battery.
Don’t remind me 😂
But none the less what you say is true. If one battery’s SOC calculations plays up it affects the total usable capacity of both.
Latest software 3017 and 309 is supposed to help fix this but I’ve not had chance to verify yet, as the charge and discharge rate of both my inverters has gone haywire since a battery was replaced on each inverter and pretty much halved the charge and discharged rates. Ive been told this has been caused by one battery not updating with the others to 3017 although could be something else too. (Engineer visit pending!).
I’d say (financial) results may a lot vary case by case with installing a second battery. If you did nothing else than simply charging it fully overnight at 7p and discharging it at 15p export later that’s £277 a year. Say £250 minus 5% conversion each way. But that not might be there for ever. Might be worse might be better !
But there are also other gains to be made;
1) converting all (or most?) of the peak that you bought (with only one battery last year) to off peak = ? (Only you will know this).
2) a cheeky extra export in the morning to soak up any clipping you might experience.
Not so obvious gains to be made as well;
2) being able to dump 4kW in an hours savings session. And still not have to import any peak in the evening (and even export what’s left still). Thats another £100pa (at £2 or so).
3) redundancy - if one fails you can turn it off and all is not lost (ie you’re not buying all at peak for a few weeks/ a month whilst you’re waiting for an engineer to attend) = £?? Which Sod’s Law dictates will always happen in winter.
4) can dump 7p extra kW’s from the battery into the car if you’re caught short. 7p vs 25p? although you won’t be able to export it for 15p
That all said, it might not be beneficial or might be very beneficial !
Payback period - who knows. Too many variables. You’ll only truly know when you break even in the end !
I’m getting 99-100% off peak all year round at 7p now, so I guess I fall into the latter category. Sharp pencil required !
Thanks for the clarification. I was hoping two batteries would mean being able to charge/discharge faster when energy prices are low/high, but it seems that's not the case, at least to a degree that matters. Being able to run more of the heat pumps off battery would also have been nice.
A secondary consideration was that I wanted to be able to reserve more for backup power (manual switchover), though the IT kit is going to have dedicated UPS, and outages seem rare here, so maybe I should just relax. 😅
And yes, I have the 5kW inverter.
Yeah, that’s correct. Only way to increase charge/ discharge rate significantly would be to get another inverter and have one battery on each. That way you’d double your charge discharge rates.
Or get a bigger inverter.
If you have a large enough array that could be split into two - that might work.
It would be nice if the charge/ discharge rates were higher.