Spent £340 building a decent van solar setup — here's what actually worked

Last spring I finally stopped talking about it and just built the thing. 200W of Renogy panels on the roof, a Victron SmartSolar 100/20 MPPT, and a second-hand 100Ah AGM I picked up off Facebook Marketplace for forty quid. Total outlay was around £340, which felt terrifying at the time but honestly changed how I use the van completely.

The thing nobody tells you is how much the wiring kills the budget if you're not careful. I spent nearly £60 just on cable, connectors, and a decent fuse block — all sourced from Amazon and a local auto-electrician who was clearing old stock. Would've been cheaper if I'd planned it properly rather than ordering bits twice because I undersized the first cable run.

Biggest regret is not going lithium from the start. The AGM does the job overnight for lighting and a 12V compressor fridge, but I'm already eyeing a Fogstar Drift 100Ah as a replacement. The weight saving alone would be worth it in a transit-based build where every kilo matters.

Anyone else built a functional setup on under £400? Curious whether people are finding lithium prices have dropped enough to make it viable at that budget now, or whether AGM is still the sensible starting point for a first build?

Really solid write-up @EwanMurray, cheers for sharing the breakdown. The Victron SmartSolar is such a sensible choice even on a tight budget — the Bluetooth monitoring alone saves you so much guesswork, especially with AGM where you can't just eyeball the state of charge.

One thing worth mentioning for anyone following a similar path: second-hand AGMs from Facebook are a bit of a lottery depending on how they've been treated. Worth running a proper load test before you rely on it for anything critical. If the previous owner kept it discharged for long periods you might find the actual usable capacity is considerably less than the label says.

How are you finding it through the winter months? Curious whether the 200W is keeping up with shorter days and the panels sitting flatter on the roof.

Really nice build @EwanMurray — £340 is genuinely impressive for that spec. One thing worth keeping an eye on with that second-hand AGM: if the previous owner ever let it sit deeply discharged for any length of time, you might find the capacity has already taken a hit even if it tests fine initially. Worth running a proper discharge test over a few cycles and logging the actual usable Ah you're getting rather than trusting the rated figure. If it starts dropping off sooner than expected, a cheap battery monitor like a Victron BMV will show you exactly what's happening. Might save you scratching your head on a cloudy week wondering why you're running low earlier than the maths suggests!

Did something similar last year — 175W panel, Victron 75/15, and a Fogstar 100Ah lithium I caught on sale. The real lesson I learned the hard way: cable sizing is where budgets quietly fall apart. Spent ages sourcing decent 16mm² tinned marine cable because the cheap stuff from Amazon was genuinely terrifying once I'd traced the voltage drop numbers.

@EwanMurray one thing that'll stretch that AGM further — set your absorption voltage conservatively around 14.4V rather than letting it push to 14.7V. Especially if it's already done a few cycles on its previous owner's watch. I ran mine into the ground being too aggressive before I wised up.

The Bluetooth monitoring through the Victron app is a game changer for understanding your actual usage patterns too. Worth every penny of nothing extra.

@EwanMurray solid numbers for that spec. One thing I'd add from running a garden office setup rather than a van — the panel angle matters enormously in the UK. Flat roof mounts on a van lose a meaningful percentage of yield compared to even a modest tilt, particularly October through February when the sun barely clears the horizon. Worth plugging your postcode into PVGiS and comparing flat vs 30° — the seasonal difference can be stark.

Also worth noting: that AGM will need a proper absorption cycle regularly or sulphation creeps in faster than you'd expect. Make sure the SmartSolar profile isn't set to a sealed battery type by mistake — caught that error on my own system and it was quietly undercharging for weeks before I noticed in the VictronConnect logs.

Really solid build @EwanMurray, and that Victron SmartSolar is a brilliant choice even on a tight budget — the Bluetooth monitoring alone is worth it for keeping tabs on battery health over time. One thing I'd flag that nobody's mentioned yet: with a second-hand AGM it's worth running a proper capacity test fairly early on rather than just trusting the seller's description. I've seen "100Ah" batteries off Facebook that were genuinely pushing 60-65Ah by the time they arrived. A simple overnight discharge test with a known load will tell you pretty quickly what you're actually working with. Saves nasty surprises when you're parked up somewhere and wondering why things cut out earlier than expected!

@EwanMurray nice one. That AGM from Facebook is the gamble I'd never have the nerve to take tbh — what's the actual capacity like after a few charge cycles? Curious if it's holding up or quietly dying on you.

Ran 160W Renogy + Victron 100/20 myself for about 8 months before upgrading the battery, and the controller was rock solid throughout. Only thing I'd flag is keeping an eye on your panel connections if the van sees any motorway miles — vibration works the terminals loose over time and you'll wonder why your yield's dropped.