Project help - Switching power from inverter to mains!

UKGadgetMan · May 2, 2012

Hello I require some help.

I have a solar system I have built myself, I have 4 *80w panels wired in parallel which connects to a 30A MPPT charge controller 12v/24V auto senses, which connects to 1 bank of 10 * Lucas 110AH Battery’s.
The Charge controller is also connected to pure sine wave 1000w inverter 12/24 auto sense.

Which all works fine, now here are a couple of questions I need help with.

When the battery bank drops to 12.30V (About 70% Battery power remaining) I want to be able to swap what the inverter is powering over to 230v mains (so that the battery’s do not get to drained which will prolong their life) but I want to do this automatically and without losing power to what I’m powering. (As I’m running a server off this system along with many other things) so it’s important not to lose power. Is there a device that can do this or can one be made or has some one already made this?

I currently plan on adding another 8 *80w panels to the system what off grip inverter would be good to use and be able except further expansion. ?

Gavin A · May 2, 2012

you'd be better off asking this question on somewhere like navitron forums, where there are a fair few off gridders, think it's fair to say this forum is pretty mains specific.

fwiw, I'd think you ought to be able to automate the switch over via some form of contactor, but you'd presumably have to have one that also cut the inverter off at the exact same time as the mains cut in (or 2 contactors with one open as standard, the other closed as standard, connected to the same relay device). No idea if such a device would comply with the regs, or wouldn't blow up the inverter though.

As for whether this could work without knocking off the server... dunno, but you could probably just use something like a small UPS for that circuit if it was a problem.

Personally, I reckon I'd stick with a manual changeover switch and spend the money on a small UPS, and more panels / batteries (have you considered running it as a 24 volt system to keep it in the ampage range for the controller, buy 2 more panels etc?)

UKGadgetMan · May 2, 2012

Thank you for your reply, yes I will be planing on moving over to 24volts I'll be doing this when I get my other panels. Already got UPS on the plan lol. Cool thanks for your advice..