Tony777

Hi does anyone know what can cause dc voltage to be present on the Growatt solar voltage sense line. The voltage can be measured at the solar input running on battery. This is with only the sense wire connected to the mppt board. I think this voltage is causing my error 08. With nothing but the ribbon cable connected to the mppt board the voltage on the solar input rises to about 74vdc measured with a multi meter. After about 70v it also shows up on the inverter lcd. I just can find where this voltage is coming from. I know it’s a fault on the main board, as I have swapped control cards and removed the diode and igbt from the mppt board and the voltage is still there. The voltage is still there with the dc bus disconnected from the mppt board.

Thanks for your time Coulomb.

Please help Coulomb.

The inverter does give 230V AC and works. Just can’t get it to charge the batteries.

I also removed the protection caps and it’s still there.

Hi maybe you could help me. I am trying to repair my Growatt inverter that is showing error 08 when changing the batteries. Something on the main board is pushing high voltage back to the solar output via the sense resistors. I have removed the diode and igbt on the inverter and I still see 70v on the solar output with nothing connected and only running on batteries.

https://powerforum.co.za/topic/888-circuit-diagram-help-needed-repairing-alfa-p-300024-off-grid-inverter/ My inverter is just like the one in the link. Does anyone have the values of the resistors on the under side of the board specifically R 91 and R 102 or a high res picture of the underside. How hot does the step up transformer usually run at idle. Mine is running at 60 degrees Celsius only running a 6w led. Might be because I have not got the correct resistors installed.

I managed to fix the problem. When I got the inverter Q24 was blown up so the inverter would not switch on. I had no schematic so I guessed and installed a 2N3904 when it should have been a 2N 3906. In my fiddling I managed to burn some resistors on the board.

Hi this is what the inverter does when you switch it off. It cycles like this continuously. e521e54b-07d9-4dcc-ba5f-63006a18fe9a.mp4

Some pictures

Thanks for the help. I thought normal behaviour was that if you turned the switch off it would just turn the 220vac off. Then maybe go into standby after a while. What is the normal behaviour of the genuine units.

The behaviour is the same as when you run it from mains and don’t have a battery connected.

🤣 The problem is when you leave it off, sun is down and also remove the mains. Then it beeps then restarts and does this continuously. I would expect it to keep the lcd on for a while then go off. ( Like my Growatt inverters.)

Hi maybe someone can help me. I bought a broken 3000w inverter. I have managed to fix most of the problems. I now have a 230v output. Mppt works… It is a rebranded Apert inverter I believe. The problem I have is when you switch the inverter off then it doesn’t stay on in standby mode. It keeps restarting every 2 seconds. So you can’t set any menu items that require standby mode. If you connect solar or mains then it stays on just not when only on battery it restarts. I think it has something to do with the Sps power supply.