Anyone else finding the Victron MPPT 100/20 struggles to keep up on cloudy winter days?

Been running a 200W panel (single Renogy mono) into my Victron SmartSolar 100/20 on my static van up in the Peak District, and I'm getting a bit disheartened with the figures I'm seeing through December and January. On a properly overcast day I'm lucky to see 3-4Ah going into my 100Ah AGM by mid-afternoon. The battery's sitting at around 60% most mornings after running a 12V compressor fridge overnight plus a bit of phone charging and LED lighting.

I've read a few threads suggesting a second panel wired in parallel might help squeeze more out of the low-light hours, but I'm not sure if the controller would handle it well or if I'd just be throwing money at the problem. My roof space could technically fit another 200W panel if I angle it slightly differently to the first one — though shading from a roof vent is a mild concern on the second position.

Has anyone actually doubled up their panel array on a similar setup and seen meaningful gains through winter? Or would I be better off just accepting the limitations and adding a bit of mains hook-up capability as a backup for the darker months?

@NickThompson65 know that feeling well — my static up in the Borders had the same story last December. Single 200W panel into a 100/20 and I was watching the VictronConnect graphs like a hawk wondering where all the watts had gone.

Thing is, the panel itself becomes the bottleneck in thick overcast, not the MPPT. My turning point was adding a second Renogy 200W in parallel — suddenly the controller actually had something to work with even on a grim grey day.

The 100/20 can handle up to around 580W of panel input (at 12V), so you've got headroom. Before writing it off, check your actual panel voltage under cloud in the app — if it's barely tickling above battery voltage, the MPPT is doing everything it can but there's just nothing there to harvest.

@NickThompson65 Here's the thing nobody tells you until you're already disheartened and knee-deep in VRM data: a single 200W panel in the Peak District in December is essentially a very expensive ornament for about 14 hours of the day, and a modest contributor for the remaining four.

On the boat I've learned to stop expecting miracles from winter solar and start treating it as "keeping the battery from total despair" rather than "running the setup."

The 100/20 itself isn't your problem — it's perfectly capable of handling everything that panel can physically throw at it in those conditions. The bottleneck is photons, not electronics.

What's your battery capacity? Because the real question isn't whether the MPPT is keeping up — it's whether your bank is sized to bridge the inevitable grey stretches.