I have a 4.6 kW Goodwe. But I’m guessing that the 4.6kW (or 20A) applies only to the backed up circuits. So if we have the kettle, the dishwasher and the microwave running at the same time as the pool pump we’re OK because the pool pump isn’t backed up and so it doesn’t count to that 4.6kW limit.
But during the day when it’s sunny the pool pump receives solar power from the panels via the inverter. If it’s not sunny and the grid is up then it still gets supplied by battery (I think).
So what is the flow of power around this thing? It can, given sufficient PV, charge the battery and service the backed up and the non-backed up loads. But the conversion of DC from the panels to AC that can supply the loads happens via an inverter, which is circuitry and therefore must have a limit.
What I see is when AC load goes up early in the morning then the battery gets less. But there’s only as much PV as there is.
What’s working for me here is a … parsimonious attitude towards electricity. Water heating is on a timer, so is the pool pump, and I try to create time slots during which other stuff can happen, so we seldom have 4.6 kW of stuff running at any one time and so the inverter can send PV or, on gloomy days, battery to the backed up loads.
I presume that all systems have similar limits. EG an 8kW sunsynk can only support 8kW without help from the grid. Admittedly that’s a lot more headroom than I have.
Yes, the PV power will be deployed first and if this isn’t enough then the inverter battery.
However I believe it’s also a priority to get your battery charged before nightfall.
I don’t think so. Not with the Goodwe. Running it in the default mode it might not charge the battery all the way left to it’s own devices. So I run it on TOU mode, set to charge from grid if necessary between 15:00 & 16:00 to get to the situation you describe.
So if my backed up load is 3.5 kW, outbuildings are pulling 2kW, then total load is 5.5 kW and even if there is lots of PV then 900W must come from the grid?
What I have read of the way systems are managed is that when you are struggling with capacity the way to go is to power your load(s) with grid power. Once the squeeze is behind you you resort to PV/battery power.
The idea is not to charge your batteries from the grid since these can be charged from PV as and when…
It can do 6.4kW from the PV all day long, as long as:
There is at least that much available from PV
The load profile is correct.
In terms of the load profile, it can only do 100A or 4.6kW to the battery (whichever is lower). And also only 20A or 4.6kW to AC. So in order to take 6.4kW from the panels, you have to have a mix of AC load and battery load (ie battery must not be fully charged). If the AC load exceeds 4.6kW (essential+non-essential), the PV total will be limited to 4.6kW (ie no charging the battery).
Thanks for that information. I have upgraded the PV from 4kW to 6kW (across 2 strings in different directions) so I’ll not get to 6.4. The matter of load profiling is interesting. It means working out, to the extent you can, what runs when.
6kW seems a lot to me. My main breaker is 60A. What are you supposed to do with that? Arc welding?
Indeed!
If I saw 6kW being generated or being consumed I would be getting nervous.
I suppose if you make a point of turning on every appliance at the same time then you might get there. (Of course I don’t have an A/C or underfloor heating)
PS: Then you come across 40kW and 25kW PV inverters in the classifieds :
Well, you can still only output 20A on the AC side of the inverter. But if you start using the oven and stove, or the geyser switches on and you have other normal loads, you can quickly get past 6kW.
In a sane world, you could have a base load of 600W, export 4kW and charge the battery at 1800W with this inverter. It is really designed for a market where export is the norm.
With a bit of management you can avoid these peak loads. (Hopefully not on a ToD schedule!)
I’m encouraged to see that grid feeds to domestic homes hasn’t gone up to the next level despite more gizmos that we now have plugged in…
New gizmos are much more efficient. I quoted figures here before comparing my old and new deep freezes. The new freezer has an extra 70l, yet it consumes 1/3 of the power and hardly ever goes over 100W. It’s literally like running a single incandescent globe.
Don’t I know it. So I have loads staggered. Water heating runs at a certain time and thou shalt not run the dishwasher whilst the water is heating. But now that we have extra panels I am back at square one: Having to explain nicely that we don’t have unlimited free electricity that we can use any time of day.
I was going to say that I can see how a home could get to 10kW (I have 2 geysers for a start, and a pool pump, and all the modern appliances), but that 60A breaker is 13.8 kW, so maybe it’s not so implausible.
