My current set-up consists of 3 Axpert MAXII 11KW in parallel (1 inverter/phase), connected to 6 x Greenrich Lithium batteries U-P5000 via an ad-hoc Voltronic cable (BMS inverter port to the RS485 batterie port).

The issue is that even though the inverters’ program 16 is set on OSO, it seems that the batteries are still getting charged by the utility at night.

What I am trying to achieve is to make the most of the solar & batteries combined, with batteries only getting charged by the solar.

 

You will find here attached more details on the current set-up

Thanks for your help.

Kind regards / Yves

Inverter & battery set-up.pdf

It could be a firmware problem. What is the main (U1) firmware version?

Hello Coulomb,

Thanks for your reply.
According to my WatchPower monitoring app, here are the firmware details:

Main CPU firmware version 00075.03

Secondary CPU firmware version 00069.01

I hope that helps. Thanks.

Kind regards, Yves

On 2026/06/21 at 6:00 PM, Yves Ducommun said:

Main CPU firmware version 00075.03

Sadly, I have only one 75.xx firmware in my collection, 75.85. So IF it's a firmware issue, this might fix it. The hex file is dated June 2025, so if your inverters' manufacturing dates are later than this, don't bother with updating to this firmware. There is no way to go back to your 75.03, except by asking your inverter supplier for an update file.

Edited June 23Jun 23 by Coulomb