Swapped out the old shore power setup on my 28ft narrowboat — anyone else gone full solar?

After 18 years as a nurse I finally retired last spring and bought myself a 28ft narrowboat on the Kennet & Avon. Lovely thing, but the previous owner had left it entirely dependent on shore power hookups and a tired old 240Ah lead-acid bank. Fine if you're sitting in a marina, useless if you want to actually go anywhere for more than a weekend.

I've spent the last few months slowly converting it over. Currently running two 200W panels on the roof (Renogy monos, bolted flat rather than tilted because of bridge clearance — I know, I know), a Victron SmartSolar 100/30 MPPT, and I've just replaced the lead-acid with a single 200Ah LiFePO4 from Fogstar. The difference has been remarkable honestly. Even in this grey October weather I'm pulling 20–30Ah on a decent day, which keeps the lights, a 12V compressor fridge, and phone/laptop charging ticking along fine.

My question is about the engine alternator side of things. The Beta 38 diesel charges the old split charge relay at the moment and I'm worried it's not going to properly charge the lithium properly — I've read you really want a B2B charger rather than relying on the relay. Has anyone fitted a Victron Orion-Tr Smart on a narrowboat? Wondering whether the 30A or the 18A version makes more sense for my setup.

@RetiredNurse43 interesting setup to inherit — shore power dependency on a narrowboat is a real pain once you start wanting to cruise properly.

I'm motorhome rather than marine, but the principles are identical. Victron kit is the obvious starting point — a MultiPlus-II as your inverter/charger gives you seamless switching between solar, shore, and alternator input. Pair it with a couple of Fogstar Drift 100Ah LiFePO4 batteries and you've got a solid, reasonably affordable foundation.

For a 28ft boat your roof space is limited, so panel efficiency matters more than on a larger vessel. 200W of high-density mono panels feeding a Victron SmartSolar MPPT controller would be my minimum recommendation.

Key question before sizing anything properly: what's your daily consumption in amp-hours? Run a proper audit first — everything else follows from that number.

Really lovely project @RetiredNurse43, congratulations on the retirement and the new adventure!

One thing worth flagging for a 28ft narrowboat on the K&A specifically — you'll have decent sun exposure on the roof but watch your panel placement around bridges and low tree cover, particularly through some of the wooded stretches. A lot of boaters underestimate how much shading knocks back output on cloudy UK days.

Also worth thinking about a small DC-DC charger to top up your batteries from the engine alternator when you're cruising. On shorter winter days you'll be grateful for that backup without needing to hunt down a hookup.

What battery chemistry are you looking at? LiFePO4 has become much more affordable lately and the weight saving on a narrowboat is genuinely noticeable. Happy to help spec something out if you share your rough daily usage.

@RetiredNurse43 28ft of narrowboat and you spent 18 years dealing with other people's emergencies — bet disconnecting from shore power feels about as liberating as handing in your bleep 🔌

Seriously though, my Hilux conversion runs a pair of Fogstar Drift 100Ah lithiums fed by Victron MPPT and the difference vs lead-acid shore-dependent nonsense is night and day — you'd want something similar on the K&A where marina hook-ups are basically a polite suggestion rather than a guarantee.

Roof space on a 28-footer should give you decent panel real estate, though mind the bridges obviously — Renogy 175W slim panels sit low enough to avoid most drama.

What's the existing inverter/charger situation looking like, anything salvageable or pure skip fodder?

Great project @RetiredNurse43, welcome to the canal life!

One thing I'd flag that nobody's mentioned yet — on the K&A you'll get quite a bit of tree cover through some of the prettier stretches, particularly around Bradford on Avon and heading west. Worth thinking carefully about panel placement and whether you want to add a small wind turbine as a supplement for those cloudier winter days when you're moored up under the willows.

What battery chemistry are you going with? LiFePO4 is the obvious choice for the weight savings on a boat, though the upfront cost stings a bit. Also worth checking your mooring agreement — some sites on the K&A still charge a flat rate even if you're completely off-grid, which feels a bit cheeky but there it is.

Happy to share specs from my own narrowboat setup if that'd help!

Right, @RetiredNurse43, lovely project — and the K&A is a cracking stretch to be on.

Since you're coming from an emergency background, I'd strongly recommend building your system around a proper battery monitor from day one. I run a Victron BMV-712 on my narrowboat and it's transformed how I manage the bank — you know exactly what state your batteries are in rather than guessing.

Pair that with a Victron SmartSolar MPPT controller and the whole lot talks to the VictronConnect app via Bluetooth. On a 28ft boat your roof space is limited, so every watt of harvest efficiency genuinely matters.

One thing nobody's said yet — shading from bridge holes and towpath trees on the K&A will catch you out. Factor that into your panel placement before you commit to mounting positions.