All-In-One Solar Charging when off-grid

Hi - does anyone know if our solar should continue to charge our AIO battery/power the house load if power goes down at the grid side? If i cut off mains supply in to the house (at the DNO cut-off breaker), the battery takes over supplying the house as expected, but we're seeing a "grid fault" on our solar inverter.

On some level I'd expected any solar generation to power the house at this point, with any excess flowing in to the battery. I can sort-of see why this wouldn't be the case if solar generation was low at the time as the gateway would have quite a time constantly switching the load between intermittent solar and the battery.

Interested in anyone's views...

It should as long as the solar is wired into the right place - I believe specific connection in the gateway.

TX200 - thanks... that was my installer's initial view too, and they're following up directly with GivEnergy support to get clarification. All inverter wiring is through the Gateway, and not grid-side.

I just thought i'd post here in the meantime to hear if anyone else has been able to prove solar charging happens in an AIO when the grid is down.

I don’t believe solar will work as there is no grid 50hz frequency to sync too.

morgs thanks - makes sense. i wasn't sure if the battery invertor might be able to emulate the grid frequency somehow via the Gateway, so that at least any excess solar would get pushed to the house load.

the more i think about it though, that would make any over-generation on the solar side pretty difficult to dump anywhere... the only obvious place being the battery, and i'm guessing the AIO battery can't provide power and charge at the same time!

It does support PV when grid is off

https://givenergy.co.uk/products/all-in-one/

TX200
Your correct is does state
“ Gateway also facilitates a connection point for solar PV systems, allowing continued energy generation even without a grid supply.”

Would like to have Givenergy confirm this.

morgs @TheDragon (GivEnergy) can you confirm that the statement on the website above is accurate?

😁

TX200 yes. Tested works fine.

Many tests involved flipping the grid supply breaker and spending the day off grid

TheDragon (GivEnergy)
So you are saying, home solar PV systems can continue to generate during grid failure with the added benefit of the battery reserve ?
Will this continue for several days if the battery has enough energy to start the PV inverter each morning and isn’t depleted during the day ?

morgs

Should do, I think it turns the PV off when the battery gets high, then on again as it drops.

Good to know. Thanks

kram How does it do this? The only connection on the default wiring diagram is a 240Vac mains cable ie PV is connected to the gateway by a twin pole switch and and RCBO - there is no comms link between gateway and PV inverter.

Tested the off-grid function.
Happy to report AIO supported uninterrupted home supply and also solar generation continued
😊

Pandorian I suppose could it potentially do this just by dropping the AC frequency to the solar invertor, and essentially forcing the AC inverter in to its in-built "grid fault" mode?

morgs nice - thanks for confirming! 🙂 could you was solar generation going to battery too, or was solar generation less than house load ...so solar generation was going to house load and then being topped up by battery?

JTG
Didn’t notice exactly.
Solar was generating only around 300W and house load would be also around 350W.
Tested for about 5 mins

In off grid mode it knocks the PV inverter offline if it needs to via frequency shift. Basically when the AIO gets near full it ups its own little microgrid frequency to 54Hz which makes the PV inverter trip and stop output (I believe a more sophisticated version is coming by moving the frequency gradually from 50>54Hz which allows the PV inverter to ramp down in little steps rather than this quite blunt on/off approach but that's basically how it works right now)

hoggy Thanks for that. Not the most elegant of control techniques forcing another device into a failure mode.

hoggy ...and i'm guessing the fact that the battery always keeps some element of charge in reserve means it should always be able to emulate the grid frequency, and keep solar generation going during any grid outage (and avoid leaving you in a situation where the AIO charge level is too low at the time of a grid outage, so it can't emulate 50Hz, which in turn would mean solar couldn't flow in to the house and/or battery either)

realise that's a pretty far fetched scenario, but still interesting to know about!

i wonder if our solar invertor (non-GivEnergy) is in some way not seeing a frequency it's happy with from the Gateway/AIO so is going in to grid fault. could possibly be an over-sensitivity issue on the solar invertor side?

Pandorian yes it could (and probably will eventually) be a bit more sophisticated that it is but to be honest without direct control over the PV inverter there are only so many tricks you can pull to control it.
It's the same problem for Tesla Powerwalls & Victron which do the same thing.

You could equally push voltage out of bounds & achieve the same result but that's a bad idea so for the sake of perhaps your oven/bedside clock running slightly fast if it's one that uses Freq for timing it is the more sensible approach available.

JTG On full grid fail, I'm not sure how much is kept in reserve, I guess it depends what you set it to yourself? Ultimately once it is completely flat it probably is game over still. Your PV won't start without grid & your AIO won't start if it's completely flat but I guess the question is how often is that likely to happen?

I'm unsure of what the equivalent of a National Grid black start is for a flat AIO if your grid is still going to be out for days? Generator I guess to wake everything up?

Pandorian

Frequency shifting to make the PV inverter stop. Powerwall does different frequencies if you have a supported inverter to throttle rather than just on/off, but I don’t know if the AIO does similar or just on/off.

You will have to be careful with PV that can output more than the battery can charge, but that’s discussed by people who know more than me elsewhere.