Our narrowboat electrical refit — before and after

Right, finally got round to documenting this properly. Spent the better part of two years piecing together what I reckon is a fairly bulletproof system for a 57ft narrowboat.

The core setup:

• 8x 400W Renogy panels on the roof (split between two strings)
• Victron MultiPlus 48/5000 inverter/charger — honestly the best decision I made
• Victron SmartSolar MPPT 250/100 (handles the panels beautifully)
• 48V LiFePO₄ bank: 20.5kWh usable (four Battle Born modules)
• Victron BMV-712 and Color Control GX for monitoring

Why these choices:

The Victron kit's overkill for some, but when you're living aboard full-time and want to run a decent workshop, you need reliable redundancy. The GX gives me remote monitoring from the towpath cafe, which is genuinely useful.

Went lithium because the weight saving was crucial — hull's rated for it. Lead would've needed replacing every 4-5 years anyway. The Battle Borns integrate properly with the BMS.

Roof space was the limiting factor, so 8x400 made sense. Could've done 10x smaller panels but mounting would've been a nightmare on the curved roof.

The messy bits:
Cable runs through the gunwale were fiddly. Used proper marine-grade trunking throughout. Shot the weight distribution wrong initially — had to move two panels forward to keep the bow trim sensible.

Been through two winters now without drama. System's rock solid in winter grey skies too, though obviously summer performance is where it shines.

Mate, two years well spent if you ask me. Narrowboats are brilliant for this stuff—fixed footprint, no planning permission nightmares, proper weight distribution for batteries.

Question though: how are you managing the water ingress on those battery boxes? I've got similar spec'd up in my static caravan and the humidity off the canal would have me paranoid. Also, what's your charging strategy when you're moored up for weeks? Solar alone or are you committing the cardinal sin of running the engine?

Genuinely interested in the cable management too—always looks like spaghetti in the engine bay on mine.

That's a proper build, @SolarJunkie. Two years sounds about right—you can't rush this stuff on a boat, there's nowhere to hide when something goes wrong in a 57ft box.

8x panels is solid. What's your battery config? I'm running 400Ah LiFePO₄ on mine and it's been a game-changer for winter mooring, though the upfront cost is eye-watering. If you've gone lithium, worth fitting a decent battery management system—I use Victron and it gives me proper visibility into what's happening.

The fixed footprint thing @BorderVanLifer mentions is the real advantage here. Unlike a van, you're not constantly repositioning for sun angle. You can plan your setup around where you actually moor.

What charger setup have you got for when the solar's not cutting it? Running a Honda inverter gen or are you tethered to marinas more often?

The fixed footprint advantage on a narrowboat is exactly why I've been eyeing one as a backup to my current setup. Two years sounds spot on—I've learned the hard way that rushing battery sizing or charge controller spec just creates headaches down the line.

What's your battery chemistry and capacity looking like? I'm curious whether you went lithium or stuck with AGM/LiFePO4 hybrid. The thermal management in a narrowboat cabin is quite different from my shepherd's hut—condensation and temperature swings can absolutely murder lead chemistry cells if you're not careful with ventilation.

Also keen to know your inverter sizing. I've seen too many boats undersized there, then owners get frustrated when they can't run a kettle and microwave simultaneously. Victron's gear holds up well in the damp environment, but I'd want to see your actual load calculations before recommending anyone follow suit.

More pics of the wiring looms would help too—cable routing matters more than people realise in confined spaces.

Have you sorted thermal management on yours? I'm looking at a narrowboat conversion myself (got a shepherd's hut on land but fancy the flexibility of water-based living) and the condensation situation seems like it could be a right nightmare—especially with a sealed battery box and inverter running in such tight quarters.

What's your battery chemistry, and are you venting the inverter separately? I'm trying to work out whether I should go LiFePO₄ or stick with lithium, partly because of how much heat each setup generates in a confined space. The boat's narrower than most vans, which makes passive cooling tricky.

Also curious—with 8 panels on a 57ft, are you getting decent winter output given the angle constraints of a narrowboat roof? That's been my main worry for the canal system.

Brilliant thread this. @SolarJunkie, I'm curious about your battery management strategy—are you running separate circuits for engine start versus house bank, or have you consolidated? I'm looking at a similar retrofit on mine and the wiring decisions are doing my head in.

Also keen to know how you've tackled voltage drop over the length of the boat. I've read horror stories about people discovering halfway through that their 2/0 cable wasn't sufficient, especially if you're running high-draw inverters at the bow end.

@CornishBoater, thermal management is massive on boats. The bilge temperature swings are mental compared to static setups. Have you considered how condensation will affect your electronics if you're adding extra kit?

What Victron equipment are you using for monitoring, @SolarJunkie? The Cerbo GX seems popular for narrowboats given the space constraints.

Mate, this is exactly the sort of project I've been following closely. The narrowboat advantage is real—I'm watching how much simpler your thermal load is compared to my tiny house setup. No roof angles to worry about, confined space means better heating efficiency.

What's caught my eye is how you've presumably had to work around the length constraint for solar placement. Are you running panels along the roof the full 57ft, or concentrated amidships? I'm curious whether you've hit any shading issues from the canal-side trees—that's the bit nobody mentions until you're already committed.

@CornishBoater, thermal management on boats is genuinely trickier than land-based setups. The water acts as a heat sink, which helps winter but murders summer. Worth factoring in ventilation alongside your battery cooling.

Two years well spent, @SolarJunkie—that's the sort of patience that actually pays dividends on a boat. The thermal side is crucial that @CornishBoater mentions it; narrowboats are essentially steel boxes in winter, so your battery placement matters more than most land setups.

I'm running something similar on my own boat (smaller system, mind—45ft), and the thing that's made the biggest difference is keeping my Victron MultiPlus in a decent spot away from the engine room heat. Condensation was an absolute nightmare before I sorted that.

One thing I'd flag for anyone considering this: monitor your actual daily draw patterns across seasons. Summer and winter consumption can swing wildly depending on where you're moored. In winter, heating genuinely reshuffles your priorities—suddenly solar contribution drops just when demand peaks. That's where a sensible battery buffer really earns its keep.

Also worth noting: if you're planning any shore power interface (winter mooring contingencies), the isolation transformer becomes non-negotiable. Learned that one the hard way.

Would be interested to see what you're running for monitoring. Are you logging consumption data

The thermal management side is crucial on a narrowboat—you're basically living in a metal box. I've seen folk get caught out with battery heating in winter, especially if they're not running the engine regularly.

What I'd push back on slightly is the 8x panel count. Depending on your roof space, you might struggle with shading as the boat moves through locks and under bridges. I'm running six 400W panels on the motorhome and honestly, five would have done the job 90% of the time. The sweet spot seems to be around 3-4kW rather than oversizing.

@BayTim's question about circuit separation is spot on though. Separate fused circuits for propulsion vs. habitation loads makes troubleshooting about a million times easier. Worth the extra wiring cost.

Are you planning to integrate any load management, or is it purely manual switching? That's where a lot of narrowboat systems fall down—people get lazy about discipline when weather's poor and suddenly they're running the alternator at idle for hours.

Two years and you're still not finished, you mean—that's the narrowboat way innit. Seriously though, the modular approach beats the hell out of retrofit chaos; I've watched mates bolt everything on at once and spend the next eighteen months debugging why their Victron's having a mood.

The real flex here is probably the thermal layer you've sorted—most boat conversions treat insulation like it's optional, then wonder why they're running 3kW of heating through a shoestring battery bank. Seen a few setups round the Pocklington marinas that are just expensive space heaters at this point.

What's your actual winter consumption looking like? I'm genuinely curious whether your figures justify the panel layout or if it's more "future-proofing for the van conversion inevitably parked beside it" territory—because I definitely recognise that particular form of optimism in my own setup.

I'm genuinely curious how you've tackled the battery placement and ventilation—that's where most narrowboat builds go sideways. I spent far too long chasing phantom voltage drops before realising my lithium was tucked in a dodgy spot with zero airflow, creating a thermal nightmare come summer.

Two years sounds about right, honestly. I initially thought I could knock mine together in six months before learning that boats have a way of teaching you humility. The real kicker is that every decision cascades—your battery location affects your cable runs, which affects your charge controller placement, which affects your monitoring options.

Did you go for a Victron setup? I'm running a MultiPlus II on mine and the remote monitoring via the app has been invaluable for catching issues early, especially during those months when the narrowboat's just sat there between trips.

Would be keen to see the actual specs when you get round to posting them properly. Narrowboat electrical is such a niche game in the UK that solid documentation is genuinely useful.

Been following your thread since the start—proper solid work. The modular approach makes sense on a boat where space is at a premium and you can't just knock through a wall if you change your mind.

One thing I'd flag that I don't think's been mentioned yet: how are you managing the charge controller placement relative to your batteries? On my setup in the van, I learned the hard way that running long cable runs between controller and bank absolutely murders your efficiency. Lost nearly 8% over a summer before I relocated the Victron closer. With a narrowboat's length, that's potentially significant if your solar's mounted on the roof and batteries are forward.

Also curious whether you've future-proofed for a second battery bank? Most folk start thinking about expansion about eighteen months in—especially once winter's taught them how quickly 400Ah actually depletes when you're running heating, laptop, and kettle simultaneously.

The thermal side @ExChippie mentioned is spot on though. I'd add that a decent blanket over your battery box (ventilated, mind) makes a measurable difference to winter charging performance in a metal enclosure.

The modular approach is spot on for boats, though I'd flag one thing that caught us out on the motorhome conversion—ventilation around lithium banks is critical, especially in the damp environment you've got on a narrowboat. We initially had our Fogstar LiFePO4s in a locker with "adequate" airflow, and after a humid winter the BMS started throwing temperature warnings constantly.

Worth considering a small 12V extraction fan on a thermostat if you haven't already. Keeps moisture migration to a minimum and lets the cells breathe properly during charge cycles.

Also curious about your battery placement relative to the engine room—thermal transfer can be an issue if they're too close to the genset, particularly during winter running. What's your actual physical layout looking like? The weight distribution matters less on a narrowboat than a motorhome obviously, but the thermal planning is actually more critical given the enclosed cabin space.

If you've got the posts documenting the installation methodology, that'd be genuinely useful for others attempting similar builds. The gotchas always seem to be the installation details rather than the component selection itself.

That's a cracking build, @SolarJunkie. The modular approach genuinely does work well for tight spaces—I learned that the hard way with my garden office setup, where I kept having to shuffle components about.

One thing that strikes me: have you considered how you're managing thermal regulation around those batteries during summer? Narrowboats can become proper greenhouses when moored up in July, and I've seen lithium setups get temperamental. With my Victron setup, I added a small 12V fan on a thermostat—cost about forty quid but gave me peace of mind.

Also curious about your inverter placement. Is it mounted remote from the battery enclosure, or are you keeping everything central? The voltage drop over longer cable runs isn't usually an issue at 48V, but the heat dissipation can be if you're running high loads (kettle, oven preheating, etc.) in a confined space.

The two-year journey definitely shows—this isn't a rushed job. Reckon you've sorted the solar orientation for canal-side living as well, or are you relying on mooring flexibility?

Proper job on the documentation, @SolarJunkie. Two years of suffering so the rest of us don't have to—that's the spirit.

The modular angle reminds me why I went Victron kit for the shepherd's hut instead of some all-in-one monstrosity. Means when a battery module inevitably gives up the ghost at 3am in January, you're swapping one brick instead of rewiring the whole boat whilst standing in water.

Only thing I'd add: make sure those battery terminals can actually breathe in a boat's microclimate. Condensation's a proper battery murderer in enclosed spaces—found that out the expensive way.