Batteries full, solar production stopped

Bianchiintenso

Just a quick question. While waiting for octopus to process our SEG I noticed for the first time yesterday that the Solar production had dropped from 3kwh to 300w when the house draw was low and the batteries were full. I was expecting it to maintain production and send back to the grid free of charge, Is this normal? 

Martyn1981

Hi, should be exporting, so sounds odd. But any chance it was a coincidence and the sun was no longer at a good angle, cloud etc etc?

Just spitballing, but any chance it wasn't a generation figure you were looking at, but a house consumption figure, so when the batts were full, it was then only showing the consumption left (and export/generation was shown elsewhere)? I know that sounds a bit stupid, and a long shot, but maybe worth checking?

Bianchiintenso

Martyn1981 said:

Hi, should be exporting, so sounds odd. But any chance it was a coincidence and the sun was no longer at a good angle, cloud etc etc?

Just spitballing, but any chance it wasn't a generation figure you were looking at, but a house consumption figure, so when the batts were full, it was then only showing the consumption left (and export/generation was shown elsewhere)? I know that sounds a bit stupid, and a long shot, but maybe worth checking?

Thanks @Martyn1981, no definitely the generation figure on the app. First thing I did was turn on the ashp and within a few minutes the generation figure jumped to cover it... strange 

pete-20-11

Is it a recent install? Is there a chance that the installer has set it up wrong, e.g. CT clamps around the wrong mains cable or pointing in the right direction etc. 

Bianchiintenso

Yes Pete, a 2/4 month old install, not sure how I'd check the CT clamps

Martyn1981

Bianchiintenso said:

Martyn1981 said:

Hi, should be exporting, so sounds odd. But any chance it was a coincidence and the sun was no longer at a good angle, cloud etc etc?

Just spitballing, but any chance it wasn't a generation figure you were looking at, but a house consumption figure, so when the batts were full, it was then only showing the consumption left (and export/generation was shown elsewhere)? I know that sounds a bit stupid, and a long shot, but maybe worth checking?

Thanks @Martyn1981, no definitely the generation figure on the app. First thing I did was turn on the ashp and within a few minutes the generation figure jumped to cover it... strange 

If the inverter gen rose, when you added more demand (good call by the way), then it certainly seems like something very odd is going on. It is possible for some 'clever' inverters to be export capped, rather than generation capped*, but that would be to prevent export of more than 3.68kW, not zero!

*Apologies if I'm teaching granny to suck eggs, but you need permission from the DNO to export more than 3.68kW, so many PV/inverter arrays that are capable of exceeding this, will be capped at 3.68kW. But a much better solution, especially if you have batts, is to cap the inverter at 3.68kW export (not generation), allowing greater generation as household consumption will be deducted.

I'm entirely, completely out of my depth here now, and again just spitballing, but maybe you have a 'clever' inverter, and its export has been wrongly set? Really weird suggestion / guess though.

Bianchiintenso

I'm just as out of depth, found this info on the inverter forum
"Limit to load will limit PV power to follow essential loads and all non essential loads will not be powered. to export power when batteries is 100% SOC you need to select zero export and then export as well. "
I'm wondering if it's a setting issue on the inverter
PS it's an 8*kW system and DNO obtained 

Martyn1981

Bianchiintenso said:

I'm just as out of depth, found this info on the inverter forum
"Limit to load will limit PV power to follow essential loads and all non essential loads will not be powered. to export power when batteries is 100% SOC you need to select zero export and then export as well. "
I'm wondering if it's a setting issue on the inverter
PS it's an 8*kW system and DNO obtained 

Fascinating. We really need a clever bod who has experience. My guess is that in attempting to set up the 'rules' so the battery doesn't export to the grid, the installer has mistakenly set the whole system to avoid exporting to the grid.

Purely out of personal interest, as I suspect you do have a 'clever' inverter, do you know what the inverter can produce, how much can be redirected to the batts (instead of being inverted (is that a word?) to AC), and how much total. I'm only asking as this is something that really opens the door to larger PV systems, now that panel efficiency (power) is so much higher. My 235Wp and 250Wp panels are roughly the same size as current 350Wp+ panels, so clearly roofs can now produce more and more v's the standard 3.68kW limit.

Bianchiintenso

I've found some settings on the inverter, the solar export was not 'ticked' so I've changed as per the below, fingers crossed, and thanks for your replies
PS the pic below is from manufacturers source, not my actual inverter which I think says 8000w inverter power limiter

ispookie666

You will need to check what the export limit has been imposed by your DNO before you go around changing the setting. You could potentially be putting your supply, Installer and your grid supply at risk. 

@Martyn1981i don't think it's given that 3.68 will be accepted as baseline export. DNOs can enforce 0 export limit. 

Bianchiintenso

ispookie666 said:

You will need to check what the export limit has been imposed by your DNO before you go around changing the setting. You could potentially be putting your supply, Installer and your grid supply at risk. 

@Martyn1981i don't think it's given that 3.68 will be accepted as baseline export. DNOs can enforce 0 export limit. 

Thanks Isppokie,  have a G99 certificate stating 8kW