Bran

We are pretty good consumption wise. I’ve never measured it exactly but around 4kWh max 5kWh per 24h day. All cooking and water heating is gas. Low wattage lights everywhere. Laundry and vacuuming is only for sunny days. No pool or anything like that. Hairdryers are banned 😄 Biggest single consumption is fridge and second is pressure pump (water is also off grid). These are also the two things you cannot really switch off if the weather is bad either. I’m not adverse to adding a few more panels, but for for now they seem sufficient. On a sunny winter day they easily charge the batteries from empty to full. It’s the week long rains that are the problem and then more panels won’t help much anyway. The problem I have is just how to add more batteries to the axpert - or an alternative inverter that can handle dual batteries, that has a PV input voltage of < 70V. Otherwise I have to rewire the entire system.

Sorry, meant separate battery strings.

What brand/model? Can it run parallel battery strings? 18A is a bit low though (my axpert max input is 60A). I don’t mind having parallel inverters (redundancy if one goes faulty), but not all inverters can be in parallel and have separate batteries.

No, but a new set would be anyway…

Thanks, that’s an option. I’m pretty happy with my mecer 200Ah, but I don’t use them at their full rated capacity of 43.2-56.4 which I think is a bit excessive. So hopefully still many years left.

2 panels in series so max volts around 70-75V Max power around 3000W So max current going into the inverter is around 42A <120A DC is ‘extra low voltage’. So I don’t need electricians ect… The axpert 5k minimum solar voltage is 40V. I’ve not seen anything on the market that is even close to that. Probably because it’s cheaper to have higher voltage lower current.

I have a small off grid solar system: 12 x300W panels. The panels are wired in 6 strings of 2 each. The strings face different directions, east, north or west (this gives maximum hours of power rather than midday peak power). This setup is high current - low voltage (which I prefer as low voltage DC is not regulated and it’s much safer). Inverter is a Axpert 5K (which is good for low voltage - high current) Batteries are 4x mecer 200ah lithium second life. Backup generator. With judicious use of electricity the system works really well. My conundrum is that I want to increase my battery capacity to last longer during the miserable Cape Town winters, however mecer says that you cannot use their batteries in parallel and I cannot find an inverter that is capable of running two strings of batteries and suitable for low voltage - high current setup. Even two Axperts in parallel need to be connected to the same battery string. Without rebuilding my entire solar system are there any clever solutions out there that don’t break the bank?