How much solar do you need on a campervan?
Enough to make a genuine contribution to your daily power use — but solar is rarely the whole answer on its own. How much you need depends on what you use, and just as much on when and where you travel, because a panel's real output swings enormously with the season. Here is how to think about it honestly.
Rated output is not real output
A panel's wattage is measured in ideal lab conditions — full, square sunlight, cool temperatures. In the real world, on a van roof, in British weather, you get a fraction of that, and the fraction varies hour to hour and month to month. So you cannot read the number on the panel and assume that is what it puts into your battery. Plan around realistic output, not the rating, or you will be disappointed.
Season changes everything
This is the single most important point, and the one most often glossed over. A panel that comfortably covers your needs on a long summer day may deliver only a small share of that in midwinter, when the days are short and the sun is low and weak. In a Scottish December, solar is a useful top-up at best; chasing the sun in southern Spain or Portugal, the very same panel does far more. If you travel year-round, you have to design for your worst realistic conditions, not your best.
Solar is one charge source, not the only one
On most vans that live off-grid, solar works best as part of a charging strategy alongside the others: engine charging while you drive (via a DC-DC charger), and hook-up when you have it. Solar's great strengths are that it is silent, fuel-free and works while the van sits still — perfect for days parked up in good light. But leaning on it alone, especially in winter or poor weather, is how people end up flat. Match it with your other sources rather than expecting it to carry everything.
How much, then?
Work back from your daily power budget — the same figure that sizes your battery. Fit as much good-quality panel as your roof and budget sensibly allow, knowing that more capacity buys you more resilience on dull days and through winter. There is rarely a reason to under-fit solar if the roof space is there; the limiting factors are usually roof room, shading and budget rather than 'too much'.
The bits that make solar actually work
Good panels are only part of it. A correctly sized MPPT charge controller gets far more out of the panels than a basic controller, especially in the marginal conditions where you need every watt. And the install matters as much as the electronics — sound wiring and properly sealed roof fixings, because a leak does more harm than a poor charge ever will.
How we would help
We size and install solar to genuinely contribute for how and where you travel — not just to fill a roof — and we integrate it with your engine and hook-up charging so the sources work together. Tell us your usage and your travels, summer and winter, and we will tell you what solar can realistically do for you.