Array kW vs Inverter maximum

Apologies if this has been asked elsewhere.. I've searched and can't see anything.

Just had a new array fitted of 20x385W panels so 7.7kW array. Inverter is a GivEnergy Giv-HY 5.0kW attached to an 8.2kWh battery.

On the web dashboard, the generation has maxed at 5.3kW on two very (very!) sunny days. I understand the inverter can't allow more than 5kW power though but surely the generation stat on the dashboard should be accurate to the panels, ie at least above 6kW??
TIA for any wisdom..

Was the battery charging, or full? I spotted our HY3.6 peaking at 5.2kW (on a 5.47kWp array) yesterday, but once our pair of 8.2 batteries were full, this throttled right back to the max it could pass through on AC.

@Benns06 . You have not mentioned whether your 20 panels are all facing due South, or an East/West mix, or whether there is any shading. These all affect the actual output, compared with the potential output taken from values on a data-sheet.

Simon_C All 20 panels face due south and are in full sun on a sloping roof so should perform optimally.

Also where the inverter is, if overheat is also an issue.

But that inverter has a max of 6500w, so depending on the above you should be able to see up to 6.5kw

adamdoran Battery is charged every morning and is full by 10am but my question is more about the power generated by the panels (on the new dashboard, the yellow figures). Surely these should go above 5.3kW on 7.7kW array... my fear is that some of the panels are not working or are not connected.

Once the battery is full, the limiting factor is the maximum a/c output of the inverter at 5.0 kW nominally. Once this limit is reached the inverter will automatically adjust the power operating points of the solar panels away from the optimal, so the 5.0 kW from the panels is all you will see. The power is not dumped in the inverter, it is potential energy from the sun that gets wasted as additional heat in the panels themselves. Remember that solar panels are only around 20% efficient at converting solar energy in to electricity, the remaining 80% is absorbed as heat in the panels.
When the battery is not full, the inverter can potentially receive up to 6.5 kW from the panels, with some to charge the battery and some used for a/c output to your home/grid.

I'm currently dumping the battery to grid from 0630 to 0900 and setting the battery charge to around 1200w.

That way my 6kw south facing array isn't clipping and I'm using all I generate, seen a sustained 6.2kw of output from it this week.

Frankly I think a HY5 is a little underpowered for your array size given its south facing, even with some active battery management to get it to charge over the peak time of day to use above the 5kw the inverter can deal with you will still see a fair amount of clipping for any generation above 6.5kw.

Today I've seen above 5kw at 1600 for example, yes it's nearly the longest day of the year but high power outputs are also common during the decent days of sunshine over winter due to the low ambient temperature.

As some already mentioned, any excess generation above 5kw with a full battery has to go somewhere and it ends up as heat - this isn't good for either the panels or the inverter in excessive amounts.

yandards .
Not sure the 'excess generation' in your last sentence is strictly correct in electrical terms, and could be misleading to some.

With a solar intensity of 1000 W/m2 (as used on solar panel data-sheets), a recent panel capable of 20% efficiency and an inverter operating the panel at the maximum power point, for each 1 m2 of panel area, 200 W electrical power is generated and conducted to the inverter, and 800 W of heat is dissipated in the panel.

With the inverter switched off, or the DC input throttled right back by the inverter MPPT tracker, there is no electrical power generated by the panel, so all 1000 W is dissipated as heat in that 1 m2 of panel, and 0 W passing through the inverter.

It is only a 25% increase in power dissipated as heat, and the panels should be designed for the condition of the inverter being switched off without causing damage due to overheating.

The inverter is supposed to be designed for 5.0 kW a/c output, so should have a suitable cooling system in place to cope with the losses caused by electrical inefficiency. Some users have experienced output throttling due to high inverter heatsink temperatures, so have added fans to force ventilate and reduce the temperatures of the GivEnergy designed passive heatsink.

Benns06 ie at least above 6kW

Looking at the comments on this thread, you can see that different people have different priorities. If you want to maximise your grid export to make the most from your SEG tariff, then starting a forecast sunny day with plenty of capacity to charge your battery but then throttle charging to <1kW would result in the battery taking all day to charge which would reduce clipping and (after satisfying house load) maximise grid export.

The way I look at surplus PV is that it means I can be self-sufficient from earlier in the year to later in the year but clip during the sunniest months. Our kit was installed during the last week of January this year and other than two or three occasions when we purposely charged an EV from the grid and discharged the house batteries to the EV during the evening by mistake (Zappi had reset to ECO rather than ECO+ mode), we have been self sufficient since day 1. We have been averaging under 1kWh from grid each day since the end of January because of the inverter response times and the number of times they have to chase heavy load switches ( kettle/oven/iron-the worst). This is offset by our SEG tariff from Octopus which at the moment covers the daily standing charge and consumption, but that'll fall of in the autumn. I think that when it isn't so sunny, you will be glad of PV in excess of the inverter capacity.

By the way, if a 60l petrol tank has 20l of petrol in it, it has 40l of ullage - it's capacity to full. Does anyone know what the word would be for a battery that has a capacity for further charge? An 8.2kWh battery at 50% SoC has the capacity to store another 4.1kWh, so a what of 4.1kWh?