Emergency Inverters

[bn12595]

Currently I have an on-grid 3 pole mounted arrays of 9 panels, 9 panels, and 6 panels (all 230W Solon panels). The two 9 panel poles have Enphase M190 inverters and the 6 panel pole has the newer M215 inverters.

None of these inverters will operate without backfed power from the grid.

I would like to be prepared for a major event (like an earthquake) that creates a situation where the grid is unavailable for months). Is it possible to have a large inverter (2000W) for one of the 9 panel poles that could be placed in service and would not require on-grid power. I envision being able to disconnect the panels from their individual micro-inverters and feeding them all through this one 2000W inverter so that I can have some power from the pole. The inverter would have to be located outdoors at the pole and it would be nice if it had multiple incoming connection points for each panel. Is this just a pipe dream?

[Eric]

There are a couple ways to do this.

One issue is how to hook the new, battery based inverter to the loads. Were you thinking of just running an extension cord(s) into the house? That would be one way to do it. You could have a whole separate combiner box, charge controller, battery bank, and inverter, at the pole, and in the event of disaster unplug each panel from its microinverter, and plug them into the wires that lead to the new combiner box. One issue would be keeping the batteries charged in between disasters. You could have a AC trickle charger for that.

The other way to do it is an "AC Coupled" system, where there is an inverter which gets wired in between some or all of the microinverters and the grid, and a critical loads subpanel. When the grid is up, the whole system works as now, when the grid goes down, the inverter has a transfer switch which disconnects from the grid, and the output of this inverter keeps the microinverters running. This probably would require some rewiring of the house to create that critical loads subpanel. It is a little counter intuitive how the whole thing works, there are some documents online if you want to pursue it.

[rlrmd]

From these posts do I learn correctly that micro inverters stop working when the grid goes down and therefore no need for some kind of separate disconnect switch to prevent grid back feed?
Also is it possible to use some sort of a Y on each panel's out-put wires such that one side of the Y goes to the micro inverter and on to the grid while the other connects serially to a single wire that goes to a battery controller and on to charge batteries ...?

[Eric]

From these posts do I learn correctly that micro inverters stop working when the grid goes down and therefore no need for some kind of separate disconnect switch to prevent grid back feed?

Yes

Also is it possible to use some sort of a Y on each panel's out-put wires such that one side of the Y goes to the micro inverter and on to the grid while the other connects serially to a single wire that goes to a battery controller and on to charge batteries ...?

That could work. I haven't actually heard of that being done, would be a lot of switchgear because when the microinverters are working you should keep all the panels separate.

[rlrmd]

Thank-you!
Re. "switchgear" - could that be like a ? diode in each Y on the battery charge side ?? not sure I even know what I'm asking ...

[Eric]

Diode might work, but I just meant some type of switch.