I don't both count how many stupid questions I ask, but I'm sure it will count against me eventually.
My system is comprised of 12 Hengdian 450 PV panels, Fox H1-5.0-E-G2-WL inverter and Fox IP12 battery and what is would like to understand is what happens when the generated PV kW exceeds the inverter rating.
Points to note:
1) my NDO G98 approval is for 5kW output.
2) the inverter, as I understand (don't take a bet on that) it, is that the inverter can operate up to a max of 6kW with a nominal rating of 5kW.
3) I have witnessed the PV output exceeding 5kW, sometimes all the way up to over 6kW.
What happens in these instances? Given that the panels and the battery are DC coupled, does the excess (in the event that the battery isn't full) just go to the battery and isn't lost?
You might ask why the question?
Well, the little devil in the back of my mind keeps whispering about extra panels and another battery. The extra panels would certainly at times exceed the rating of the inverter, hence the question.
Many thanks for any responses.
Best regards,
The Rock Pusher.
Hello again trouble 
If you check your spec sheet on your inverter, you can see it can support 2x MPPT trackers. Max 6kW in a single tracker, or 10kW combined for PV1 & PV2. So your hard limit is 10kWp (12x450 = 5.4kWp currently) estimate you could put 8-10 panels max with your current inverter.
In terms of my system, with a lower 3.9kW export limit, but bigger inverter. I typically make 'room' in the battery to mop up the overspill from my larger than your array (6.16kWp) so I have SoC around 60% on sunnier days, and all the excess goes into the battery. It is important to note, you have to run your system in the 'feed-in' work mode for this to work out correctly.
1. I think you mean you have a G99 for 5kW export (G98 is a lower limit)
2. 5.5kW is your peak AC limit, it can I believe passthrough the DC directly to the battery with a 10kW PV limit, and 40A on the DC battery side.
3. I agree, the system does well in Spring, the wind the other day was cooling the panels and the PV output was better. The Summer output will be lower peaks, but as the days are longer, you generate overall more PV in total.
I would be careful in thinking about adding more panels and battery, as you don't know that the current export price you are getting will stay stable, if you begin to use more power (example you get an air-source heat pump) then increasing your battery/PV capacity will offset the costs.
If you check your spec sheet on your inverter, you can see it can support 2x MPPT trackers. Max 6kW in a single tracker, or 10kW combined for PV1 & PV2. So your hard limit is 10kWp (12x450 = 5.4kWp currently) estimate you could put 8-10 panels max with your current inverter.
In terms of my system, with a lower 3.9kW export limit, but bigger inverter. I typically make 'room' in the battery to mop up the overspill from my larger than your array (6.16kWp) so I have SoC around 60% on sunnier days, and all the excess goes into the battery. It is important to note, you have to run your system in the 'feed-in' work mode for this to work out correctly.
1. I think you mean you have a G99 for 5kW export (G98 is a lower limit)
2. 5.5kW is your peak AC limit, it can I believe passthrough the DC directly to the battery with a 10kW PV limit, and 40A on the DC battery side.
3. I agree, the system does well in Spring, the wind the other day was cooling the panels and the PV output was better. The Summer output will be lower peaks, but as the days are longer, you generate overall more PV in total.
I would be careful in thinking about adding more panels and battery, as you don't know that the current export price you are getting will stay stable, if you begin to use more power (example you get an air-source heat pump) then increasing your battery/PV capacity will offset the costs.
Thanks again MB.
I will be careful in thinking about expansion, it's just a current theme ticking over in the single digit IQ range of my brain.
It's the thought of bridging over bad cloudy days between good days but with UK weather I'd need an atlas of clouds.
Thanks for the insight.
Best regards,
Derrick.
I will be careful in thinking about expansion, it's just a current theme ticking over in the single digit IQ range of my brain.
It's the thought of bridging over bad cloudy days between good days but with UK weather I'd need an atlas of clouds.
Thanks for the insight.
Best regards,
Derrick.
Hi Derrick,
My best overall recommendation would be to wait a full year if possible to get a year's worth of figures, then at least you have an A to B comparison if you do decide to add to the system.
My best overall recommendation would be to wait a full year if possible to get a year's worth of figures, then at least you have an A to B comparison if you do decide to add to the system.
Hi MB
Yes, that's what the little chap with wings and a halo in the back of my head says, but the little chap with the horns and a tail seems keen to empty my bank account.
But, given the performance I'm seeing - 32kWh from PV and 21.3kWh exported yesterday (all despite Trump's transports and bombers contrails obscuring the Sun) it's becoming difficult to justify adding more to my system. But another battery is still tempting to tide me over cloudy days after days like yesterday. Adding to that, my installer says the same as you.
It's a learning experience.
Best regards,
Derrick.
Yes, that's what the little chap with wings and a halo in the back of my head says, but the little chap with the horns and a tail seems keen to empty my bank account.
But, given the performance I'm seeing - 32kWh from PV and 21.3kWh exported yesterday (all despite Trump's transports and bombers contrails obscuring the Sun) it's becoming difficult to justify adding more to my system. But another battery is still tempting to tide me over cloudy days after days like yesterday. Adding to that, my installer says the same as you.
It's a learning experience.
Best regards,
Derrick.
So your array done very well, to compare 'notes'
5.4kWp = 32kWh for you
6.16kWp = 34.10 kWh for me (clouds did impact here and there)
You didn't do too bad on reflection, and I think if export tariffs fell through the floor, then you best investment will be an extra battery to mop up the energy on the good days to spread it over to the poor days.
I had same thoughts as you, I have a very large roof without solar panels on! I could double my solar output, and have even more North facing roof available, so I could reach I around 18kWp maybe or not far off. Sadly unless I had loads of battery capacity, or jumped to 3-phase that all wouldn't be worth doing.
5.4kWp = 32kWh for you
6.16kWp = 34.10 kWh for me (clouds did impact here and there)
You didn't do too bad on reflection, and I think if export tariffs fell through the floor, then you best investment will be an extra battery to mop up the energy on the good days to spread it over to the poor days.
I had same thoughts as you, I have a very large roof without solar panels on! I could double my solar output, and have even more North facing roof available, so I could reach I around 18kWp maybe or not far off. Sadly unless I had loads of battery capacity, or jumped to 3-phase that all wouldn't be worth doing.