In searching for inverters that could run a 3000 – 4000 watt load in an off-grid solar system, I found some low cost inverters on eBay (SUN-2500P is the model I see on these). An issue soon came up after putting them in service. If anything happens, and the inverter trips, it never comes back on-line until I go out and manually reset the inverter. This is a showstopper for a number of reasons, so I set out to find a way to auto restart the inverters.
The units are controlled by a DPST switch. I wanted to have the units normally running, or normally off depending on the state of a toggle switch, and have a signal put the inverters in to the other state to to either reset or power on the inverter.
So I took a DPDT toggle switch and a DPDT relay and connected the throws together. I spliced the poles in series with the switch already in the inverter so if it is turned off, the inverter goes off regardless of the relay status. Made a small assembly and mounted it by removing one of the air slot cross members.
Here is an idea of what it looks like:
I connected wires to the really coil, put a strain relief zip tie to the assembly and ran them out of an air slot. While this is not the most professinal modification, it saved me from a show stopper situation with these inverters. I am testing these running 2 units ganged together to run a 3KW load with some success. The long term reliability of these inverters is still in question so in the end I my end up with a higher end solution. Time will tell.
This solution ran well for a few months, but for some unknown reason, they both blew up. The company that sells these was unresponsive, so I paid up for one big, higher end inverter, and it has worked well for about a year now.