thomasquinn93 avatar image
thomasquinn93 asked

How to automatically switch pv array from MPPT to Grid-tie inverter

First question on the forum so be gentle with me!


Recently due to rising UK energy prices I built an off-grid "Solar Generator" using a 405W panel, MPPT 100/30 charge controller, 24v/500W Phoenix inverter and DIY 7s10p 24V 18650 Li-ion battery... all worlking as intended. The battery is charged during the day, and its used to run appliances and charge things during the night.

I would like to use the same panel with a small G98 certified grid-tie inverter, so that once the battery is charged each day, the panel connections are automatically switched from the MPPT 100/30 charge controller, to the grid-tie inverter.


Can I use the TX port of the MPPT 100/30 to trigger some sort of 2-pole relay, that would allow the switching of the pv + & - from the MPPT CC to the grid-tie inverter once my battery is fully charged? Do I need to use a Smart Battery Connect somehow to make this work?

Any help would be greatly appreciated.

MPPT ControllersRelayswitch
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1 Answer
raphael avatar image
raphael answered ·

I wrote a detailed text...but than the website crashed.
So just a short answer now...sorry:

Yes, you can do it:

But I would recommend a BMV700 or BMV712 smart.
Than you have SOC monitoring and you can swich any 24 V relay with up to 1 A current with the potential free contact of the Battery monitor.

You have to flip one of the PV-wires at least. A 2-pole relay would be better of course, but not necessary.

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