Yes, 2 x3.6kW would do it, they would have a combined passthrough of 70A so you could have the whole house on the UPS side leaving just the EV chargers on the grid side. I am assuming @Smallholder has all the circuits accessible in the one place, but some ppl on here have the panels 10s of m from the house or like me a garage across the driveway, now is the time to tell us!Krill wrote: ↑Mon May 08, 2023 9:32 pm
Personally I'd have a look at the Sunsynk 3.6kW hybrid inverters, they don't look that expensive and have greater inverting power then the name suggests. It's probably worth considering to just get two (or even three if you really want to be paranoid about ability to not cap total production) installed by a professional and get them to do the paper work, and then connect up additional battery banks and PV arrays as any when needed. That way everything is legit and can be sold on if needed.
The 8.5 kW of PV makes the inverters a bit over-panelled but by an acceptable amount, there is just enough to supply the 7kW EV charger, and the curtailment at the height of summer is when there will mostly likely be a surplus anyway.
According to the instructions https://cdn.shopify.com/s/files/1/0257/ ... 1672913323 the Sunsynks will work without a battery attached, which prompts the thought of getting a single one installed under MCS and adding the second one and the batteries later.
There doesn't seem to be any setting for export power limit (p 49), it's either ON or OFF. So it's not clear if with a master-slave setup you can set them to be different in order to limit the combined export power to 3.6kW. But you could just forget aboout export.
To comply with UK regs you need to install an external neutral-earth bonding relay but at least there is a signal to drive it (p23. I think the word "not" is missing from the description!)
