New install, gradual decline in Solar PV output
Posted: Tue Jun 23, 2026 2:12 pm
Hi all,
I have a new installation of a H1-3.7-E-G2-WL hybrid inverter and a EP12 Plus (w) battery. The system has 2 strings covering two sides of the roof, each with 3 x 515W panels. It all seems to be working as expected. I have the inverter linked to Home Assistant, so handy for logging the data.
A couple of days after it was all commissioned, during the first break in the clouds, the system generated 3.1kW peak for a while, but was generally up around 2.8kW while the sun was out during the day. Since then, it seems the max has dropped to 2.3kW max. Even though we have had wall to wall clear skies. I've checked and the scaffolding isn't causing any shadows during the peak of the day, but the solar PV output seems to be some 40% down on the max. The inverter can supply 3.7Kw from the battery, or as a combination of battery and solar PV. It just seems the PV output isn't where I'd expect it to be.
Our previous installation, on the same roof, didn't show any where near the same percentage difference. It had developed a fault after 12 years, so we took the opportunity to replace it and add a battery.
The system has produced what, in theory, the maximum is it can produce. But it seems to be slowly declining. I know temperature plays a part, but I can't see it causing this much of a drop. The installer is back next week, as the bi-directional meter is backwards. The Net value is getting ever more negative, even though we are just charging the battery from the PV. To maintain the FIT payments, this needs to be solved. It was a nice surprise to find out we can keep receiving FIT payments, they just pro-rata the payment down to the old capacity, so 3.09kW to 2.57kW.
The inverter is running Manager 1.33, Master 1.47 and Slave 1.04 firmware. The integrated manager is on 2.09, as I could update that. I see no option to update the firmware on the inverter itself. I did e-mail Fox support, got a case number, but heard nothing since.
Anyone have any suggestions as to what could be happening with the PV?
I have a new installation of a H1-3.7-E-G2-WL hybrid inverter and a EP12 Plus (w) battery. The system has 2 strings covering two sides of the roof, each with 3 x 515W panels. It all seems to be working as expected. I have the inverter linked to Home Assistant, so handy for logging the data.
A couple of days after it was all commissioned, during the first break in the clouds, the system generated 3.1kW peak for a while, but was generally up around 2.8kW while the sun was out during the day. Since then, it seems the max has dropped to 2.3kW max. Even though we have had wall to wall clear skies. I've checked and the scaffolding isn't causing any shadows during the peak of the day, but the solar PV output seems to be some 40% down on the max. The inverter can supply 3.7Kw from the battery, or as a combination of battery and solar PV. It just seems the PV output isn't where I'd expect it to be.
Our previous installation, on the same roof, didn't show any where near the same percentage difference. It had developed a fault after 12 years, so we took the opportunity to replace it and add a battery.
The system has produced what, in theory, the maximum is it can produce. But it seems to be slowly declining. I know temperature plays a part, but I can't see it causing this much of a drop. The installer is back next week, as the bi-directional meter is backwards. The Net value is getting ever more negative, even though we are just charging the battery from the PV. To maintain the FIT payments, this needs to be solved. It was a nice surprise to find out we can keep receiving FIT payments, they just pro-rata the payment down to the old capacity, so 3.09kW to 2.57kW.
The inverter is running Manager 1.33, Master 1.47 and Slave 1.04 firmware. The integrated manager is on 2.09, as I could update that. I see no option to update the firmware on the inverter itself. I did e-mail Fox support, got a case number, but heard nothing since.
Anyone have any suggestions as to what could be happening with the PV?