Anyone else built a decent 12v system for under £300? Share your parts list

I've just finished putting together a basic but functional 12v solar setup for my Transit van conversion and managed to keep the whole thing under £300. Curious whether others have done similar on a tight budget and what corners you cut (or refused to cut).

My setup is a 200W panel from a seller on eBay (£65), a Victron SmartSolar 75/15 MPPT controller (£55 from a clearance listing on Amazon), and a 100Ah leisure battery I picked up secondhand from a caravan breaker for £40. Wiring, fuses, and a basic 240v inverter rounded it out to about £285 all in. It runs a 12v compressor fridge, phone charging, and LED lighting without any real bother through spring and summer.

The one thing I wouldn't skimp on was the MPPT controller and the fusing. Seen too many horror stories on here about cheap PWM controllers frying batteries or underfused wiring causing fires. The secondhand battery was a gamble but I load tested it before buying and it's holding around 85Ah, so happy enough with that.

What did your budget builds look like? Especially interested if anyone's managed decent battery capacity on the cheap — lithium on a shoestring feels like a contradiction but I've heard people are pulling it off with secondhand cells.

WonkyDrifter | 847 posts | ⚡ Solar Tinkerer

Nice one @WildMechanic! Done something similar for my shed setup last year. Key to keeping costs down was grabbing a used lithium battery from a mobility scooter off eBay - proper bargain at £45. Paired it with a 100W panel from a Facebook Marketplace seller who was clearing out, £55 the lot including the frame brackets.

Biggest saving honestly? Learning to crimp your own cables rather than buying pre-made ones. Crimping kit was a tenner and I've saved a fortune across multiple builds since.

One thing I'd say to anyone attempting this - don't skimp on the fuses and proper cable sizing. That's one area where cutting corners genuinely costs you more in the long run, or worse. What battery are you running in the Transit?

DontPanic44 | 234 posts | 🔋 Budget Builds

Great thread idea @WildMechanic! I put together a 12v system for my narrowboat last spring, kept it to about £285 all in. The trick was going secondhand for the battery - picked up a decent 100Ah AGM from a scrapped caravan on Facebook Marketplace for £35. Spent the savings on a proper MPPT controller rather than a cheap PWM unit, which honestly makes a real difference to your charge efficiency.

Full list:

• 200W panel (Renogy): £89
• Victron 75/15 MPPT: £68
• 100Ah AGM (secondhand): £35
• Fuse block + wiring: £42
• Various connectors/cable: £31

Leaves a bit of headroom for extras. Would strongly recommend not skimping on the cable gauge though - learned that the hard way! What controller did you end up going with @WildMechanic?

CamperShaun | 1,203 posts | 🔋 Battery Obsessive

Worth knowing that the battery choice will make or break whether you actually stay under £300. Fogstar Drift 100Ah LiFePO4 regularly drops to around £139 on their website — that's where I'd start the budget allocation, then work backwards.

My rough breakdown for a functional Transit setup:

• Fogstar Drift 100Ah — ~£139
• Renogy 20A DC-DC charger — ~£45 (essential if you're charging from the alternator)
• 30A PWM controller — ~£18
• Fuse/wiring/bus bars — ~£30-40
• Single 175W panel — ~£55-65 depending on sales

That's cutting it fine at roughly £290-295 but genuinely achievable. I'd skip Victron at this budget — save it for the next build when you're upgrading. The Renogy DC-DC is non-negotiable though;

MarineGuru | 2,156 posts | ⚓ 12v Systems Specialist

Great thread! One thing I'd add that often gets overlooked on budget builds is proper cable sizing and fusing. Seen so many cheap setups catch fire because someone ran undersized wire from a bargain bin. Spend a tenner on decent marine-grade tinned cable and a blade fuse holder near the battery - genuinely could save your van.

Also worth shopping around on eBay for ex-marine or boat equipment. Charge controllers and isolation switches from boat yards can be surprisingly cheap secondhand and are built to handle damp, vibration and abuse far better than some of the cheap Chinese gear on Amazon.

@CamperShaun is right about batteries being critical - if you're tight on budget, a decent AGM will serve you better than a flashy lithium from a dodgy brand.

WillWilliams | 89 posts | ☀️ Solar Tinkerer

Good timing on this thread! Done exactly this for my shed setup. Key thing I'd flag that nobody's mentioned yet - don't skimp on the cable sizing. I made that mistake first time round and lost a surprising amount to voltage drop over a fairly short run. Proper 10mm² cable from a local auto factors is far cheaper than buying it branded online and makes a genuine difference.

My rough breakdown:

• 100W panel (AliExpress) - £45
• 20A PWM controller - £18
• 100Ah AGM leisure battery (local classified ads) - £60
• Fuse box and miscellaneous cabling - £35

Came in around £158 total. @MarineGuru is right that battery choice matters massively for longevity though - if I were doing it again I'd save a bit longer for LiFePO4.

RetiredNurse61 | 347 posts | 🏕️ Static Caravan Survivor

Did mine for £287 including a Fogstar 100Ah LiFePO4, Renogy 200W panel, and a cheap Victron BlueSolar MPPT I found refurbished on eBay — the static caravan hasn't lost power once since, which is more than I can say for the NHS hospital I retired from. 🏥

PikeRuss | 612 posts | 🔧 Van Dweller / Tinkerer

Nice one @WildMechanic! Did almost identical last spring for my Sprinter. Went with a secondhand 200W panel off Facebook Marketplace (£35), a Victron 75/15 MPPT (worth stretching the budget for, honestly), and a 100Ah AGM from Tayna. Kept wiring costs down by buying cable by the metre from an auto electrical supplier rather than those overpriced van conversion kits. @RetiredNurse61 that Fogstar LiFePO4 price is tempting though - might upgrade mine next year. Main tip: don't skimp on fusing, I've seen people cut corners there and regret it badly.

ShaunWebb | 156 posts | ⚡ DIY Enthusiast

Great thread! Mine came in at £294 for a modest but solid setup — 200W panel from a Facebook Marketplace find (£45!), a Victron 75/15 MPPT which I reckon is worth every penny even on a tight budget, a 100Ah AGM from a local battery place, and basic Narva cable/fuses from eBay. Total runtime on my workshop tools has been genuinely impressive.

@RetiredNurse61 interesting you went LiFePO4 — I nearly did but the upfront cost scared me off. Kicking myself a bit now knowing the long-term value. Maybe next upgrade cycle! Anyone else finding second-hand panels on Marketplace are absolute bargains at the moment?