Inverter derating

My Easysolar II GX derates, while running at max power 23-2400 watts, it starts to derate after a while, is that normal forthe standard 3kVa Multiplus II also

Hi Tariqe, can you please tell me at what time you noticed it, I looked at your graphs quickly and can not really pick up any derating. Just an indication and I will have a look again…

Hi Jaco,
While running the the 2.3 kWh load, after a while, the pv power drops to around 2100 watts, the battery stays at 100 %, and the inverter starts drawing just under 400 watts from the grid
If I remove most of the load and let the inverter cool down and switch on the load again, it repeats the process
I noticed this first early afternoon

Theoretically yes, running any unit at 100% would increase its internal temperature, depending on the ambient temp on that day, or in the room the unit will start derating.

What you explain sounds like exactly what I would expect when a unit derates. It will take less from the DC side and more from the Grid.

Thanks Jaco, just wanted to make sure it is standard operating procedure for a normal Multiplus also

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Looked at your graphs again, just after 15hoo I can see some derating, drawing about 350watt from the grid.

Just wanted to be sure it was not design flaw with the Easysolar II GX.

Been there, seen that … perfectly normal and a very good protection meganism to ensure longevity of the units.

My 3kva derated as low as 1800w midday with ±2.8kw loads.

Therefor I upgraded to a 5kva because my loads were averaging 3kw … and the 5kva derates to 3kw at max temps.

Only option is to keep the ambient temp as cool as possible - or upgrade to 5kva.

It is normal. The Multi runs at 80% of its rating when grid-coupled (so 2400W for a 3kVA), but if it gets hot it derates to 60% (1800W).

Is this after a set amount of time? Mine definitely draws 5kW from the DC side when a few things go on at the same time…

Strictly based on temperature. On a cold day it may never derate.

Hi @plonkster, I think I remember a post in the other forum regarding hooking up a fan with a switch or something

Ah, I interpreted your other post in that it would always run at 80% when grid tied and only if it increases in temp would it go to 60%.

That is the correct interpretation. It always runs at 80% (because that’s its actual continuous all-day-the-whole-day capacity), and if it still gets too hot (because it’s spending its life in South Africa), then it derates to 60%.

Please forgive me, I have been driving for over 20 hours already, tired and not thinking straight, but I just can’t get my head around this statement of yours. I have seen multiple units running at full capacity for extended periods of time before they start derating. Where does this 80% fit in.

A 3kVA Multi will feed in roughly 2400W continuously while running grid-coupled. A 5kVA will feed in 4kw continuously. That’s because the nameplate rating is not a continuous rating, it is peak rating. If you run a 5kVA Multi at a whole 5kW (off-grid) for hours on end it will eventually overheat (how long depends on ambient temperature).

For this reason a the Multi is always limited to 80% of its nameplate rating… unless it STILL gets hot… then it will derate even further to 60% of its nameplate rating.

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So I guess in my case I would never run continuously at 5kW, which is why it would do to for say 10 minutes or so? I have definitely seen it pull 5kW out of the panels and battery combined. On the AC side this typically translated to 4500W with the rest then coming from the grid. Can’t say this was ever for an extended period though. Only way it can happen is if my geyser is on and some stuff starts firing up in the kitchen.

Did this test this afternoon, ran for a bit trying to lower the SOC = 5047w

At that level of power the Multi is maybe 85% efficient (fan running flat out, etc), so you will draw more on the DC side than it feeds into the AC side.

this is after running at this load for just under an hour, the room temperature was about 25 centigrade, the battery stays full and 297 watts is being consumed from the grid