Solar panels removed

[JohnH]

Hi, would appreciate some advice here, I need roof repairs and the panels have been removed for this. The isolator switch for the system is now off and the inverter displays 'Grid Lost Fault'. Battery was at 80% at switch off and has gradually reduced to 63% now after 5 days. All domestic use is now from the grid but the App is confused and shows nothing to/from grid at all but a trickle of charge going to the battery (34w). MinSoc and Reserve set at 10%.

So will the battery still protect itself with a grid charge if/when it gets to MinSoc? Is it safe to switch the system back on without the panels in situ? System is set to self-use so this would prioritise battery use over the grid but at least then I could charge it at the cheap rate.

Thanks

[Dave Foster]

If it is reporting grid lost fault it sounds like you have turned the AC isolator off as well as the DC (solar) isolator.

If you leave it with the AC isolator off the batteries will continue to provide the inverter with standby power and whilst it isn't much (maybe 50 watts) the batteries will discharge until they hit minSoC but they won't be able to get the maintenance charge from grid as your AC is isolated and that could damage them long term.

If you want to leave it like this power off the batteries and open the battery dc isolator, the batteries will maintain their soc for quite some time as they only lose approx 3% of their charge per month when powered off (the inverter screen will go blank).

Alternatively you can turn on the AC isolator with the panels disconnected (quite safe), in which case the batteries would be used to supply the house load, and you could charge them from grid from time to time if you have an eco tariff.
They will also be maintained by grid when they reach minSoC - ideally the best approach if you run like this is to raise your minSoC to say 20% to give you a bit of headroom in case you have to disconnect the system in the near future.

If you don't have a low tariff (like an EV or economy 7) there isn't much point in keeping the system on and charging from grid as you'll end up paying for the losses and the power the inverter uses to stay out of standby so best to turn everything off including the batteries.

[JohnH]

Thanks Dave
I've got two isolator switches (big circular red knob thingy's) - one labelled 'Solar PV system' which is the one I've turned off, this must have isolated both the DC and AC simultaneously. Should I have separate isolators? (The other isolator is for my Zappi EV charger).

I'd like to charge the battery overnight but is it OK to switch this isolator back on when the panels are not there? When you refer to the 'battery DC isolator' is that the 2 circuit breakers next to the battery power button?

[Dave Foster]

I think the one you have turned off is likely the AC (grid feed), if you don’t have a separate DC isolator which looks just like the other one (it’s not always fitted but good practice), then you use the black DC isolator rotary switch which is on the underside of the inverter (left hand side).
When that is turned off the panels are disconnected, but in all honesty if they have been removed there is never any power sent from the inverter to the panels it is always from the panels to the inverter so it will be safe.

On the batteries, yes it looks like 2 circuit breakers connected together - that will completely disconnect the batteries from the system.

From what you have said I would rotate the black switch on the inverters underside to the off position (panels will be disconnected), then turn the big red solar PV switch back on and the inverter should start to go through it’s checking states which takes a couple of minutes before settling down to ‘normal’ operation. You won’t have panels attached but it will run like an AC1 where you can charge your battery from grid on your EV tariff and they will run the house until flat when they will be float charged to maintain minSoC.

[JohnH]

Have turned the switch on the inverter off and the isolator back on and everything looks good. Many thanks Dave