Shelly Pro EM-50 as PV-invertermeter shows no kWh

Been scratching my head over something similar on the boat recently and wondered if anyone else has hit this wall.

I'm running a Victron Multiplus-II with a Cerbo GX, and I decided to bolt on a Shelly Pro EM to monitor two separate PV arrays — one on the cabin roof and one on a tiltable frame I can swing out when I'm moored up. The Shelly shows live wattage absolutely fine, real-time current and voltage all present and correct. But the kWh accumulation just refuses to populate in VRM. It's sat at zero for weeks now.

The Shelly is configured as a PV inverter meter role in the Cerbo, which feels right. I've double-checked the CT clamp orientation, confirmed the IP is static, and the device shows up healthy in Remote Console. Yet — nothing. No daily energy, no totals, just that stubborn goose egg.

A few things I'm wondering:

• Is the PV inverter role actually the correct one for measuring string output that isn't going through a dedicated string inverter? Mine feeds straight into the MPPT.
• Could the phase assignment be causing the accumulation to fail silently even when instantaneous readings work?
• Has anyone found that a Shelly firmware version broke this at some point?

I've seen a few threads hinting that the role selection matters more than people expect, and that using grid meter instead sometimes resolves it — but that feels semantically wrong for my setup.

If anyone's got this working cleanly on a similar narrowboat or off-grid setup, I'd love to know what your Cerbo role config actually looks like.

@VanNicola your post seems to have got cut off there, but I'll have a stab at what you're likely running into.

The Shelly Pro EM-50 as a PV inverter meter in VRM is a known faff. The kWh figure showing zero usually comes down to one of two things:

1. Wrong role assignment in the Cerbo GX — it needs to be set as "PV Inverter" not "Grid meter"
2. CT clamp orientation — flip it round, dead simple fix

Also worth checking your firmware on both the Cerbo and the Shelly. Victron pushed some updates recently that sorted communication quirks with third-party meters.

On my static caravan setup I had a similar head-scratcher for about a week before realising I'd just got the clamp on backwards. Felt like a right muppet. Classic.

Finish your original post and we'll get you sorted properly.

Both posts got cut off mid-sentence, which is deeply unhelpful for anyone searching this thread later.

That said, I'll throw in what I know from my own van setup. The Shelly Pro EM-50 configured as a PV inverter meter in VRM will show power fine but the kWh accumulation often silently fails if the CT clamp orientation is wrong relative to your AC output wiring. Took me an embarrassing amount of time to figure that out.

Also worth checking: the Shelly needs a stable mains reference to calculate energy properly. If your Multiplus is in island mode without a grid input, the energy counters can simply refuse to increment — it's a known quirk rather than a fault as such.

Check the CT direction first. It's almost always that.

@GafferTapeKing is absolutely right — truncated posts are the bane of any searchable forum thread.

I'll fill in the likely gap anyway, since I've burned hours on exactly this with my cabin setup.

The Shelly Pro EM-50 configured as a PV inverter meter in VRM will show real-time watts perfectly fine, but the kWh counter simply won't accumulate unless the Cerbo GX has the correct firmware and the Shelly's CT orientation is consistent. Reversed CTs give you negative flow, which Victron's energy counters quietly discard rather than sum.

Check two things:

1. CT clamps facing the correct direction (arrow toward load)
2. Cerbo on firmware v3.14+ — earlier builds had a known accumulation bug with third-party meters in that role

Fogstar batteries on my cabin system showed the same phantom zero until I sorted the CT orientation.

@GafferTapeKing fair point on the truncation issue, but let me add something concrete that might actually solve it.

The Shelly Pro EM-50 will not accumulate kWh totals when configured as a PV inverter meter role in VRM/Cerbo unless the CT orientation is correct and the device is set to the right measurement type in the Shelly app first. Victron pulls the energy counters via MQTT, but if the Shelly is seeing negative or oscillating values due to CT clamp direction, the counter resets rather than accumulates.

Had exactly this on my shore-power monitoring setup — flipping the CT 180° on the live conductor sorted it immediately. Check your Shelly web UI under Emeter data; if instantaneous watts look correct but flip sign occasionally, that's your culprit.

Also confirm firmware is current — older Shelly Pro EM builds had a known counter bug.