SmartSolar in VRM chart shows higher current than possible

Been scratching my head over something I'm seeing in VRM and wondered if anyone else has noticed this.

I've got a Victron SmartSolar 250/70 on my boat, feeding into a 48V lithium bank (Fogstar Drift cells). Two strings of panels wired in series-parallel, total Isc works out to around 36A theoretical max.

When I pull up the VRM dashboard charts, I'm occasionally seeing current readings that seem to push beyond what the panels should physically be capable of producing — even accounting for the usual margin above STC ratings on a cold bright day. I know panels can exceed their rated Isc slightly in ideal UK winter conditions (low temperature, high irradiance), but what I'm seeing looks a bit further off than I'd expect.

A few questions:

• Is VRM pulling instantaneous spike data rather than averaged readings? Could that explain the apparent anomaly?
• Does the SmartSolar's internal logging sample at a different rate to what VRM displays?
• Could there be any calibration drift in the MPPT's current sensing that compounds over time?

I'm not losing sleep over it — the system seems to be performing well and the Fogstar cells are healthy according to the BMS. But it bugs me not understanding where the numbers come from.

Has anyone dug into this, particularly those running larger arrays where the discrepancy might be more obvious? Curious whether it's a display/logging quirk or whether there's something genuinely worth investigating on the hardware side.

@ForestDweller the 250/70 rating is the input voltage max (250V) and output current max (70A) — but that 70A is at the battery terminals, not scaled to panel input.

What you're probably seeing is VRM doing something slightly odd with its data aggregation — it can occasionally show peak instantaneous readings rather than averages, which looks bonkers on the chart. Known quirk.

Worth checking:

• Are your battery voltage readings stable in VRM at the same timestamps?
• What's your panel array configured as — series, parallel, or mixed strings?

On my narrowboat setup I saw similar weirdness after a firmware update on the MPPT. Turned out VRM was just graphing a cached outlier value. Hard refresh of the portal and it sorted itself out. Also double-check your CT clamp placement if you've got external current sensing involved.

@ForestDweller the VRM chart samples at intervals and can catch a brief spike mid-sample that looks impossible on paper — your MPPT is actually doing a voltage step-down, so if your panels are pushing say 150V at 20A input, that 3,000W gets converted to ~62A at 48V output, which feels wrong until you remember conservation of energy is still a thing (P=VI and all that). Check your bulk/absorption phase timestamps — spikes usually coincide with those. Also worth grabbing the raw CSV export from VRM rather than trusting the graph's interpolation; seen my own SmartSolar look like it briefly invented electricity on that chart. @WattVicky makes a solid point about the ratings too — the 70A ceiling is at the battery terminals, not the solar input side.

@WattVicky and @MarineGeoff have both covered the main points already.

One thing worth adding — VRM's default chart resolution can make transient spikes look worse than they are. Drop the time window right down to the shortest interval and see if those peaks smooth out or persist. If they persist, check your panel Voc vs temperature — cold morning on a boat, panels can punch well above their rated Voc, which can drag more current through briefly before the MPPT settles.

Also worth pulling the History tab on the MPPT itself via VictronConnect rather than relying on VRM graphs. The device-logged peak current figures are more trustworthy than what VRM stitches together from its polling intervals.

Had similar weirdness on my garden office setup — turned out to be nothing, just VRM doing VRM things.

@GoldenSocket curious what resolution you were going to suggest before getting cut off there — assuming you mean dropping from hourly to the 15-minute or even per-minute logging?

One thing nobody's mentioned yet: are you running the SmartSolar via Cerbo GX or direct VE.Direct to something else? I had a similar head-scratcher on my static caravan setup where the Cerbo was timestamping data slightly out of sync with actual MPPT events, which made the charts look deeply suspicious. Turned out to be a firmware mismatch between the Cerbo and the SmartSolar.

Worth checking both are on current firmware — Victron Connect makes that fairly painless. What firmware versions are you running on the MPPT itself?