GivEnergy Hybrid, Solis String and Solis AC Coupled inverters - all managed in Predbat!

[steve-daedilus]

I've been busily working at trying to solve this puzzle over the last couple of months - opportunity cost of some very cheap batteries and AC Coupled inverter came up with a lot of complexity from the nature of the batteries, and I wanted to share the progress and where I'm still figuring things out:

My Solar Setup

Initial system, a GivEnergy Gen 3 5kW hybrid inverter with 2x Gen 1 5.2 kWh batteries, attached to 12x Aiko 455W panels split equally East and West. It has been in HA / Predbat since install day (5th September 2024), using GivTCP (initially v2, currently v3). I had it controlling it within a week of the installation being completed.

June 2025 - Self installed 8x 460W Bifacial Aiko panels, 5 south and 3 north on the garage, and connected up to a Solis 4th Generation 3.6kW string inverter (refurbished). Output on solar increased by +80%. Using Solis Cloud data to pull into HA the solar generation stats for this inverter - this feeds into lessons learned later...

March 2026 - Self installed a Solis RAI-3K-48ES-5G, this time with a Solis S2-WL-ST datalogger that supports ethernet and modbus communications. Added to it 14x 1.2kWh Li ion packs from a colleague who had used them to be off-grid for a couple of years. Purchased a Victron SmartShunt 500A and cabling to connect by USB to my Home Assistant VM. Learned a bit of Node-Red to get data pulled in.

Predbat, HomeAssistant and Modbus

This is where most of the work has been focused. I am using the Solax Modbus module to talk to the Solis AC Coupled inverter, and with a lot of experimentation and hunting around, I have managed to have Predbat control this inverter alongside the GivEnergy. The system has been challenging to get sorted, and still has niggles, however between calibrating the Smart Shunt and the Inverter settings for a non-smart BMS battery pack, it's now working well - charging and discharging consistently.

The hardest part of this was trying to ensure sensible multiple inverter settings to account for the larger batteries on the Solis, but with lower rate of charge / discharge due to the AC Coupled inverter. Additionally, there was also where to account for the string inverter capacity (which is not tracked natively). Initially this was on the GivEnergy, however with the AC Coupled it seemed to skew things a bit. Moving it to part of the AC Coupled made the behaviour patterns of the GivEnergy seem more balanced in how Predbat attempted to balance. I can't demonstrate what I mean exactly, but suffice to say I spent a LOT of time trawling the live Predbat Log feed going through everything and trying to get this tuned up.

Predbat is enabled for the Axle VPP integration - and this month with both inverters working well, I've already exported more than my £10 guarantee - seeing the system pushing the bounds of the 7.36kW G100 export cap I have here, even with minimal solar generation.

With the inverters now working well together, I've seen Octopus Agile negative energy price windows be exploited extremely well by the system - I've had a few negative days this month exceeding -£5 for the day!!

Things outstanding

The biggest outstanding issue I now have is with realtime data flow data in Home Assistant. The Solis string inverter data only being available via Solis Cloud is a big issue here, but not the only one. Load calculation data has become a minefield, and the Predbat energy flow chart reports frankly impossible numbers with the two inverters in the mix - my best efforts to provide the right values to Predbat remain stubbornly out of my grip. The irony is, it doesn't seem to effect the actual behaviour and decisions arrived at in the system, just I have some wild metrics that are completely not true and do not correlate with other metrics that are clearly fairly accurate and backed by Octopus daily consumption data.

Replacing the string inverter datalogger with the same one on the AC Coupled will resolve some of the issues around data currency, however there are others that I suspect I'm going to need to seek help from someone more intelligent than myself!

Lessons Learned

My key lessons learned so far have been:

1. Local control everything - for GivEnergy this was from the start GivTCP. For Solis, I was using cloud hooks, but it's not responsive and the data delays compared to local make it unsatisfactory for me to be assured that Home Assistant and Predbat have coordinated awareness of what is happening. I moved to Modbus control of the Solis AC Coupled inverter and it's been a far greater improvement.
2. Integrate everything into HA and Predbat that you can - stops fighting between the systems.
3. With multiple inverters, be prepared to tune your platforms. My mixed vendor model and mixed capabilities has meant a lot more tuning than someone running an identical group of inverters / batteries. However, it's still a good idea to let Predbat know it's dealing with three inverters individually (if that's what it's doing).
4. Get really, REALLY good at maths. Multiple inverters makes the maths around dashboarding, data flow and understanding far more complicated than it should.

[Robertmd171]

Following up on this discussion — I have a similar setup (GivEnergy hybrid + Solax X1 Hybrid G4 AC-coupled) and have published a working Home Assistant configuration for coordinating both inverters using a cascade strategy:
👉 https://github.com/Robertmd171/ha-givenergy-solax
The approach:

Predbat manages GivEnergy as the primary inverter
Solax follows Predbat's decisions via HA automations — charging alongside GivEnergy overnight, standing by during the day, then taking over only when GivEnergy reaches its reserve
Works with any fixed cheap/peak tariff (EDF in my case, but easily adapted)
All local control — GivTCP + Solax Modbus, no cloud needed

As noted in this discussion, the metrics are imperfect (Predbat doesn't "know" the Solax battery exists) but the actual charge/discharge behaviour is solid. Happy to discuss or accept PRs if others want to adapt it.