Technical Support

Hi fellow Sunsynkians,

My in-laws have a Sunsynk 8.8kW hybrid inverter with a total of 8.2kW panels on the roof (20 panels x 410W) and batteries.

Each MPPT has 2 strings of panels, so total of 4 strings with 5 panels on each string. Also got 3 batteries of 5kW each.

The whole system was installed and setup almost 4 years ago by my father-in-law who passed away recently. He had some serious electrical skills and also setup 2 other full systems in the family, and everything has been working great so far.

Recently they had to do a new certificate of compliance for insurance purpose.

I suspect the electrician who came for this certificate messed up somewhere and it seems one string of panels is now disconnected as since then, when enough load and full noon sun, MPPT2 is constantly showing double the amount of production than MPPT1.

I want to make some tests to see which string has gone bad. My plan is to switch the inverter off and start again but with only PV isolator 1 switched on, check if there is production, then off again, and start again with only PV isolator 2 switched on, etc. My questions are:

• is there a better way to check this?

• what must I switch off then back on exactly and in what order must I switch these off and then on again to be sure everything is safe and I don't damage the inverter? Is it safe to even just turn off and on a PV isolator without switching off the inverter beforehand? (like a simple circuit breaker on a DB board)

• once I find what string is faulty, is there by any chance a way to find which panels are connected to that specific string except following the relevant cables until up the roof (my father-in-law might have drawn a plan of which panels are on which strings / MPPT but we haven’t found it yet)

Thank you kindly for your help.

Oliver