PV Panel output power capped

[BrianCannell]

Hi,
I've had my PV set-up since mid Jan and very happy with it.
16x PV panels, total output 6.96kW
Inverter H1-5.0-E-G2
Battery 5kW
Version Master 1.31
Version Slave 1.02
Version ARM 1.48

Now that we have some sun, I've noticed that the PV panel output is limited to 5.04kW irrespective of how bright the day is. If I increase the load, the PV output stays the same but the grid export drops to take up the increased load. The PV output has never gone over 5.04 so it appears something is limiting the PV power output. It's as though my DNO licence limitations (5kW) are also being applied to the panel output.

I've checked the settings on the Inverter and they all align with your Inverter setup video.

Any suggestions gratefully received.

Many thanks
Brian

[Will]

Hey,

You have a 5kW inverter, meaning that regardless of how much solar you could produce your inverter can only invert 5kW.
You can normally oversize the inverter but limit the export to the approve 5kW so a 6kW might have been a better idea.

[BrianCannell]

Hi Will,

Over the w/e I've done a bit of work with the mode settings and battery SoC. It seems that as long as I have some reserve capacity in the battery, the inverter will not throttle the PV panels in their output. For sure, I'm limited to exporting 5kW into the grid, but the inverter will cope with up to 7.5kW input from the panels. Yesterday I saw 6.1kW from the panels whilst still exporting 4.8kW to the grid (I get that there will be a bit of 'safety margin' on the max export power). The evidence appears to point towards the inverter needing a load soak of the battery in order to fully utilise the panel o/p. As long as the battery can take some power, I can increase the household load upto the total PV panel o/p without dropping the grid export power.

When I'm home early enough to catch the mid-day sun I'll be doing a bit more investigation.

Cheers

Brian

[BrianCannell]

Hi Will,

Thanks for your input and sorry - I misread what you were saying about the 5kW max AC capabity of the inverter. I'm currenlty working with the installers to find out why they spec'd an inverter only capable of handling 72% of the PV panel max output.
Cheers
Brian

[Will]

Does seem that a 6kW would have suited better on review.

[twowheelsgood]

I'm currenlty working with the installers to find out why they spec'd an inverter only capable of handling 72% of the PV panel max output.

My personal perspective is that where I live in the UK, the chances of getting the solar panels running at near 100% capacity for any length of time, is vanishingly small. Most of the time they run at far smaller percentages, but having more panels than the inverter capacity means the panels can generate more power when light is less strong.

The other factor is that the price difference between a 5kW inverter and say an 8kW inverter is about 100% so you have to generate a lot more power for longer when its operating at 5kW to 8kW to justify the significant price increase. I had a similar calculation to do (assisted by folks here) with electric showers pulling 9kW and whether it was worth bothering with a bigger batteries and a bigger inverter to get ride of the spike in power demand - for what turns out to be a 20p shower. spending £1500+ to save 20p per shower made no economic sense at all.

My personal opinion is that where I live (the UK) that the amount of time the solar panels spend generating between 5 and 8kW made it not economic.

But thats just my sixpence - you'll have a bigger inverter and only have a half dozen days a year when your panels will exceed the 5kW