I will have an off grid solar panel system to run my deep well 5,5 Hp water pump. I already got 24 of 250Wp 36,3 Voc panels and 3 phase Delta VFD C2000 inverter/driver. for this system I need to wire all the panels in serial to get 540-800 Voc for pump driver. this part is ok.

I want to use another 5KVA inverter with some batteries to run devices(Tv, Fridge,...) in a small village house and 1-2 Hp small 230v motors for spraying(only during the day). I already have 24 panels for waterpump and I want to use those panels when I don't need water. however inverter can take up to 90 Voc 50 amps to charge 48V batteries. I can use some relays and make few parallel panel until 50 amp, but this system might be risky in the case of a relay fault.

if it is possible I want to reduce high Voc to match 90Vmax 50 amps inverter input for solar panels. Efficiency of dc to dc conversion is not and issue since I will have plenty of panels waiting all day for nothing. Can you please give me and idea how can I do this with low budget?

Thank you!

  • \$\begingroup\$ Can you add a diagram of what you're proposing? Following the words is rather difficult. Using relays to reconfigure the panels makes sense, but I don't understand what "relay fault" you're worried about. \$\endgroup\$ – Dave Tweed Apr 20 '16 at 16:23

If I correctly understand what you're trying to do, it seems that connecting a DPDT relay to each pair of panels would achieve what you want:


simulate this circuit – Schematic created using CircuitLab

Activate relays as needed to power the LV inverter. If a relay should drop out for some reason, there's no danger of exceeding the input voltage rating of the inverter.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.