Anyone else finding their PWM controller struggling now we're past the clocks going back?

Been noticing my old Epever Landstar 20A PWM has been pretty much useless before about 10am and after 2:30pm these last few weeks. Running a 200W panel on the van (single Victron 200W mono, south-facing fixed mount) and I'm barely scraping 20Ah into my 110Ah AGM on a clear day. This time last month I was getting a solid 40-50Ah no bother.

I know PWM struggles compared to MPPT when the panel voltage is low relative to battery voltage, and I'm wondering if that's a big part of what I'm seeing. Battery's sitting around 12.4V most mornings and the panel just can't seem to drag it up meaningfully until the sun's properly overhead. Checked all connections, nothing loose, controller reads fine.

Has anyone actually done a direct comparison switching from PWM to MPPT on a similar-sized system going into winter? Wondering if it's worth dropping £80-100 on a Victron 75/15 MPPT or whether I'm just going to have to accept that November in the UK means miserable solar regardless of what controller I'm running.

Yeah this is the reality of PWM in winter really isn't it. The panel voltage barely creeps above battery voltage at low sun angles so the controller just... sits there doing nothing useful.

Switched to an MPPT (Victron 75/15) about two years ago on my Transit build and the difference in shoulder hours is genuinely significant. Still not loads coming in obviously, but you're actually harvesting something rather than waiting for the sun to get its act together.

The maths on a single 200W panel honestly justifies even a budget MPPT like a Renogy Wanderer MPPT or similar. PWM is fine in summer when you've got plenty of headroom but October through February it's just throttling you at the worst possible time.

Worth looking at what the controller's actually costing you in missed harvest before next winter.

@BurnJim mate your PWM is essentially doing a 9-to-3 school run while the sun's out here doing a gap year — showing up briefly, achieving nothing, and heading home early.

The real villain is that PWM just throttles the panel down to battery voltage, so on a grey November morning when your panel's scraping together 13

@BordersOffGrid 😂 gap year is exactly right

Worth knowing why though — PWM can only work once panel voltage rises above battery voltage by a small margin. Low sun angle in winter means your panel's running at maybe 60-70% of rated voltage even at noon on a cloudy day, so you're basically waiting for that threshold to be crossed.

On the narrowboat I swapped to a Victron 75/15 MPPT last winter and the difference in shoulder hours was genuinely significant — it'll squeeze usable current out of situations where PWM would still be sitting there doing nothing.

If budget's tight, Renogy do a decent 20A MPPT for around £35-40 now. For a single 200W panel on a van that'd be a straightforward upgrade and you'd likely recoup the difference in actual charge within a month this time of year.

@BerlingoLife is right that it's worth understanding the mechanism. The key thing with PWM is that it essentially drags the panel voltage down to battery voltage to regulate — so when your battery's sitting at say 12.4V and the panel's only generating 13V in weak winter sun, there's almost nothing to work with. An MPPT would be harvesting usable power at that point because it can operate the panel at its actual optimal voltage (likely 17-18V on that Victron) regardless of battery state. @BurnJim with a single 200W panel on a van, the upgrade to even a basic 20A MPPT would genuinely transform your winter mornings and afternoons. Victron 75/15 or a Renogy 20A would both suit your setup and aren't expensive now.