Solar is the first thing most people think of for a van, and in summer it is brilliant. The trouble is the UK's winter. If your van needs to work in December as well as July, the charging plan has to be built around the dark months, not the bright ones.
What a panel's rating actually means
A 200W panel produces 200W under test conditions: strong, direct sunlight hitting it square on. In a British winter you get short days, a low sun and a lot of cloud. As a rough rule of thumb, a panel that gives you most of a battery's worth of charge on a long June day may give you only a small fraction of that on a grey December one. Plan for a winter day being worth a tenth of a summer day, sometimes less, and anything better is a bonus.
Why alternator charging carries winter builds
Your engine's alternator doesn't care about the weather. A DC-DC charger takes power from it while you drive and feeds it into the power station at a controlled rate.
- The Bluetti Charger 1 delivers up to 560W while driving.
- The Bluetti Charger 2 delivers up to 1,200W, combining alternator and solar input, and keeps working from the panel when you're parked.
- For units with a low built-in DC input, the D050S raises DC charging to 500W.
The arithmetic is simple. An hour of driving at 560W puts up to 560Wh back in. At 1,200W it is up to 1.2kWh, although real figures come in a little lower once cable and conversion losses are counted. If you move the van most days, even a short drive covers a lot of what you used overnight.
Where solar still earns its place
- Summer and shoulder seasons: a 200 to 350W panel can keep a weekend system topped up with no driving at all.
- Parked for days at a time: if the van doesn't move, solar is the only source that doesn't need hookup.
- Topping up the fridge load: even a poor winter day slows the drain.
Foldable panels such as the PV200 and PV350 have one big advantage over roof panels: you can park in the shade and put the panel in the sun, and angle it towards a low winter sun.
The setup we'd recommend
- Weekends, spring to autumn: a power station and a foldable panel is usually enough.
- Long trips or year round: alternator charging as the main source, solar as the top-up, campsite hookup when you can get it.
Alternator charging means running cable from the vehicle's starter battery, and the cable size depends on the length of the run and the current. Get it wrong and the cable heats up. The Roam Wired calculator will size the cable and fuse for your van, and if you're not confident with vehicle electrics, have it fitted by an auto electrician.