Battery + Panels - Max load before import

Rheumatoid

Am I right in thinking that if my inverter on my batteries is rated at 3kw and my panels are generating over 3kw that I could use 6kw on a mixture of appliances before I import from the grid? Likewise, if the panels aren't generating but batteries are charged, I can only use up to 3kw before the system will need to import from the grid?

Thanks

Exiled_Tyke

Does this depend on the inverter set up?  I have separate inverters for the PV and battery and so can do exactly this. (Although I've limited the battery to 2.4kW discharge and of course I rarely hit max on the PV so something around 2.2kW is probably a good estimate there).  

However I'm guessing if your system is set up with one hybrid inverter then it can't convert more than it's rating from DC to AC for use in the house regardless of which power source it's drawing from. 

Rheumatoid

Thanks. I have separate inverters so am hoping I can exceed 3kw when the panels are generating. 

Why/how have you limited your battery discharge out of interest?

Exiled_Tyke

I brought down the rate slightly to help preserve battery life. Whether it makes any difference at all I will never know.  But given that these batteries haven't got old enough to really know how they will behave in the long term I thought it might help. 

If my experience translates you should be fine with your two inverters.   With fine weather due this week you may get a chance to test it out! 

Rheumatoid

Presumably if my panels are maxing out at 3.7kw and the battery Inverter can only handle 3 then I would export to the grid if I am using less than 0.7 in the house?

Exiled_Tyke

Rheumatoid said:

Presumably if my panels are maxing out at 3.7kw and the battery Inverter can only handle 3 then I would export to the grid if I am using less than 0.7 in the house?

yes. That's what I would expect. (Although most 3kW inverters tend to go higher, if only for short periods. I've had 3.3kW out of mine)

I can't speak for the Sollis monitoring portal but my experiences of the solax portal are: 

1. It's designed around a hybrid inverter.  Whilst it seems accurate on monitoring what's going in and out of the battery the rest of the data doesn't always make sense (particularly to and from the grid)
2. Numbers from the various components don't reconcile. Presumably some combination of efficiency losses and inaccurate measurements. But in what combination, who knows. 

I have a friend with a full Solax set up with one inverter and it seems to produce far more meaningful information for him.   I'm happy with what it does as I'll I need to do is keep track of battery performance.  I use the Solaredge site to monitor PV production and the smart meter to look at grid import. And that's it!

Solarchaser

Yes it should work as you expect.
My panels in theory top out at 8.7kw the way I have the inverters arranged.
On a normal sunny ish day I maybe get 6kw peak, and if one of the family use a 10kw shower, my battery inverters move to stop the import, so sunny days are free showers.

If I was generating 8.7kw and the battery inverters were drawing their max of 7.2kw then after house loads the rest would go to the grid

ispookie666

Nearly.  Might be better to look at what the actual VA rather than Watts is, some of the appliances have dreadful power factor