In short I have 2 inverters, one being a grid tie (1500w) so it synchronises with the mains ac and the other just a small inverter. I want to run these off the grid but the problem is as I exceed 300w (the power limit of the smaller inverter) it drops into overcurrent mode and cuts out, losing the sine wave and as such the grid tie inverter faults as well because there is no ac to sync to. Is there anyway that I can balance the load so that I do not exceed the 300w of the smaller inverter but can still utilise the 1500w of the larger inverter?

Many thanks, Oli

  • 1
    \$\begingroup\$ Does the bigger one have a zero export option? \$\endgroup\$
    – Jeroen3
    Jul 7, 2021 at 19:42
  • \$\begingroup\$ I don't think it does. It was quite cheap, and although it was an LCD and indicator lights there appears to be no way to program other than using a jumper onto pins on the control board. The model is Sunny Boy SWR 1100LV if that helps. \$\endgroup\$
    – Sidesharks
    Jul 7, 2021 at 20:12
  • 1
    \$\begingroup\$ Unlikely it can. too old. Search for a newer inverter with grid-forming operation and/or battery backup. \$\endgroup\$
    – Jeroen3
    Jul 7, 2021 at 20:21
  • \$\begingroup\$ I don't see how with this equipment. You probably just have to split the load and have two separate legs. \$\endgroup\$ Jul 7, 2021 at 20:27
  • \$\begingroup\$ A Sunny Boy looks like a quality, respectable unit. I take it you did not buy it new? But this is a grid-tie inverter. It cannot drive a load. You are using another inverter to trick it into thinking a grid is present. Are you quite certain this has ever worked? I would expect it would not.p, and I suspect even if you fixed the balancing issue, it would still not work. \$\endgroup\$ Jul 7, 2021 at 20:33

1 Answer 1


Looks like it cannot be done. However, I have just found that with a module it can talk over RS232 which may allow me to enable an off grid mode. Thank you all for your help! Brilliant community :)


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