Help needed: Integrating Ecgsolax 6.5kW (Off-grid) with Solarman/WattSeek into Home Assistant

Been lurking on this thread for a bit and finally have to ask because I'm stuck.

Running a small off-grid cabin setup — Ecgsolax 6.5kW inverter paired with a 48V Fogstar battery bank. I've got Solarman monitoring working fine through the dongle, and I can see all my data in the WattSeek portal no problem.

Problem is I want to pull this into Home Assistant so I can set up proper automations (mainly load shedding when SOC drops below a threshold). I've found the Solarman integration on HACS but honestly struggling to get it talking to the Ecgsolax unit specifically.

Few specific questions:

• Does anyone have a working sensor.yaml or parameter list for the Ecgsolax 6.5kW? The device IDs don't seem to match any of the templates I've found
• Is there a known logger serial format for WattSeek dongles, or is it the same as standard Solarman sticks?
• Has anyone managed to get bidirectional control working, or is it purely read-only through this integration?

I've had a look through the Ecgsolax manual and the Modbus register map is in there but it's... not exactly comprehensive. Tried mapping a few registers manually but half of them return nonsense values.

Not looking for a hand-hold through the whole thing, just need a nudge in the right direction from someone who's actually done it. Running HA 2024.3 on a Pi 4 if that's relevant.

@EmmaEdwards82 classic "I've been lurking and now I'm properly stuck" energy — welcome to the club nobody wanted to join 😄

Right, practically speaking: Ecgsolax uses the same Modbus RTU registers as half a dozen rebranded Chinese inverters (SolarmanV5 protocol). In HA, grab

@EmmaEdwards82 the Ecgsolax units typically use a Modbus RTU protocol over RS485 — the Solarman dongle translates that to the cloud API, but you can bypass the cloud entirely with a local Modbus connection if you've got an RS485-to-USB adapter (CH340 chip ones work fine, about £8 on Amazon).

In HA, the Modbus integration is your friend. You'll need the specific register map for your inverter — Ecgsolax are a bit cagey about sharing these publicly, but there's a GitHub repo floating around (search "Ecgsolax Modbus registers") that covers most of the 6.5kW variants.

Key registers you'll want:

• Battery SOC
• PV input power
• Load output
• Charge/discharge current

Done this with similar Chinese OEM inverters on my own tiny house setup. The Fogstar batteries should expose their own BMS data separately via a CAN or RS485 port depending on which model you've got — worth checking.

@EmmaEdwards82 welcome aboard! Just to add to what @Titch mentioned — when you're pulling data through the Solarman/WattSeek cloud into HA, watch out for the latency. Off-grid setups are a bit trickier because you lose some of the grid-tied assumptions baked into the standard integrations.

Worth checking whether your Fogstar bank is communicating BMS data separately — if it is, you might get better real-time SOC readings going direct rather than relying on what the Ecgsolax reports through Solarman. Some folks have had success using the pysolarmanv5 library locally to bypass the cloud entirely, which cuts the polling delay right down.

What's the actual symptom you're seeing? Stale data, entities not populating, or something else? That'll help narrow it down considerably.

@EmmaEdwards82 one thing nobody's flagged yet — double-check your polling interval in the Solarman integration config. I had mine set too aggressively (5 seconds) on my narrowboat setup and the dongle would just silently drop the connection after a few hours, no errors logged, just stale data in HA. Bumping to 30 seconds sorted it completely.

Also worth checking: the Ecgsolax registers can vary slightly between firmware versions. Grab the actual register map PDF if you haven't already — some of the "standard" WattSeek templates floating around assume slightly different offsets for SOC and battery voltage, which gives you plausible-but-wrong numbers. Infuriating to diagnose.

If your Fogstar bank has its own BMS comms output, you might actually get cleaner battery data pulling directly from that rather than trusting the inverter's reported values.