Anyone else finding their Victron MPPT struggling to keep up on these grey January days?

Running a 400W panel setup (2x 200W Risen panels wired in series) into a Victron SmartSolar 100/30 on my narrowboat, and I'm barely seeing 20-30W output on most days this week. Battery bank is 2x 100Ah Battleborn LiFePO4s so the storage is fine, it's just the generation side that's killing me. Wondering if I'm expecting too much or if something's actually off.

I've checked the panels for shading and they look clear, and the MPPT is showing the correct Voc coming in (around 42V open circuit which seems right for this time of year). Just not converting it into anything useful. I know January in the Midlands is grim but this feels worse than last year somehow.

Has anyone got any data or experience they can share — what are you realistically pulling from a similar-sized array in mid-winter? Tempted to add a couple more panels but not sure if the issue is just the weather or something worth investigating first.

CrispyRigger | 847 posts

@JimChapman74 Honestly mate, 20-30W in January on a narrowboat is pretty much par for the course, especially if you're moored up with trees or a towpath bank shading you even partially. Worth checking your panel voltage in the Victron app though — if you're seeing proper Voc figures, the controller's doing its job and it's just a light issue rather than a fault.

One thing that genuinely helps on the cut is repositioning whenever you can. Even shifting 50 metres to clear a shadow can double your harvest.

What's your battery state of charge sitting at? If you're dropping below 50% regularly you might want to look at a small supplementary wind or shore power option for the darker months. Generator hire pontoons at some marinas aren't too dear either.

AngliaCamper | 1,203 posts

@JimChapman74 400W of panels in January on a cut is basically decorative, I'm afraid. I run a similar Victron 100/30 setup on my narrowboat and I've learned to just accept the misery of Q1 and manage consumption instead of chasing phantom watts.

What's killing you more than the grey skies is your panel angle — most narrowboat roof mounts are nearly flat. Even a temporary tilt bracket getting them up to 45° can genuinely double your output on low-sun days. I knocked something up from aluminium angle from Screwfix last February and saw an immediate difference.

The 100/30 itself is fine — it's not the controller that's the problem. Don't go blaming Victron for January being January.

Compo27 | 312 posts

@JimChapman74 Worth checking your panel voltage in the Victron Connect app during those grey periods - if you're seeing the MPPT hunting around trying to find the peak, that's perfectly normal behaviour in low diffuse light. One thing that genuinely helped me on similar days was making sure my panels were clean. Sounds obvious but a thin layer of grime absolutely murders output when irradiance is already rock bottom. Also, are you moored under any trees or near bridge shadows? Even partial shading on a series string will drag both panels down significantly. With only 200Ah of battery capacity you're not drawing huge amounts to stay topped up, so small gains matter more. What's your battery voltage sitting at currently?

DownsOffGrid | 634 posts

@JimChapman74 One thing nobody's mentioned yet - how's your panel orientation? On a narrowboat you're obviously limited, but even a slight tilt can make a meaningful difference in winter when the sun sits so low. Flat-mounted panels really suffer this time of year. Also worth checking for any shading from the cabin superstructure, chimney, or TV aerial - with such weak light already, even partial shading will hammer your output disproportionately due to how series strings behave. Your 200Ah bank should be fine capacity-wise, it's just a waiting game until February honestly.