Hi folks, can you sit two 9.5kw batteries back to back or are there guidance on space between batteries? I know there's guidance on the invertor gaps etc. Thinking I could put a second battery standing in front of my existing one.
Cheers,
Mick
No issues with batteries
TheDragon (GivEnergy) cheers, if you have two batteries and let's say the invertor has max throughput of 2.6kwh does that mean it will take 19kw / 2.6 hours (7ish) to charge them? I'm just wondering if the invertor will become a bottleneck for charging the batteries
michaelmcgoldrick
Yes, it will limit your charging power, and therefore also charging speed. But it will also limit your discharge power as well, so any house load over 2.6kW would need to come from the grid. The type of inverter also has some bearing on the matter (hybrid vs AC). Perhaps consider one AC inverter per battery (although that currently comes with some limitations as well)
michaelmcgoldrick Another point to consider is whether you actually need a battery that large. Size the battery correctly (will it be used with PV, what's your daily summer/winter consumption, etc?) and it will deliver a far higher ROI than an oversized battery.
stevelewis
For what it's worth, we chose to prioritise self consumption over return on investment, so we went for the twin AC inverters, each with an 8.2kW.h battery. In others words, it allowed us to use more of the solar energy we had harvested, on subsequent days when solar was not so good. I also liked the idea of some element of parallel redundancy - but as I mentioned above, it does have some downsides, as follows:
1) Despite being installed as a Master and Slave, the two systems do not track each other, in terms of load sharing, charge sharing or SOC.
2) The two systems sometimes cross-charge, meaning that one battery discharges into the other, so the inefficiencies in the DC-AC and then AC-DC conversions mean a drop in total SOC, for no gain (apart from a slightly warmer garage).
3) Many of the values seen on the Portal and App are just nonsense, as GE does not seem able (or willing?) to set up their calculations to take multiple inverters into account.
We use about 500kwh per month. At the moment have a hybrid invertor with 9.5kwh battery and gen 1 hybrid inverter which is going to be replaced by a gen 2 in the next couple of months. Only have the system since the start of November so need to give it a year to see how it goes. Most days we can get from 8am to 11pm (peak electric rates) on the battery. Sometimes it runs out a few hours earlier if there's zero solar or a lot of usage. Or course electric showers etc use grid import anyway so it's unlikely would avoid any import. More battery would probably guarantee that coverage till 11pm each night but the cost of the battery probably means it's not worth it. I'm sure for spring/summer will see different results.
michaelmcgoldrick
If you have a hybrid already, the twin AC option is probably a non-starter then, as I believe you cannot mix the two - although I think I remember someone saying they had done it anyway.
ToothyChris out of curiosity, what is your normalised annual throughput coming out as? (average daily kWh passed through battery/battery capacity in kWh).
stevelewis
Our system has only been in a few months, and we are only just now about to get Economy 7 operational, so I probably can't answer that question just yet. But I can say our average daily electricity use is about 11kW.h, most of which will come via the batteries, in the winter. Summer will be different of course....