Marine Gaz

The charge controller is definitely key — @Foggy and @48VWizard are spot on there. But for a narrowboat specifically, series usually wins out. Four 400W panels in series gives you proper voltage...

My setup here's been pretty solid through the winter outages we've had: Got a 10kWh LiFePO4 bank (mix of Fogstar and Renogy cells) paired with a Victron Multiplus 48/5000.

Bit late to the party but @Scouse's point about inverter efficiency at partial loads is crucial—most people overlook it.

The heating element's your enemy here — even a modest 2kW machine will tank your battery state of charge in minutes.

Fair points from the crew above. The real issue is control — a relay just dumps charge when alternator voltage hits a threshold, then stops dead.

Good points from @ForestBoater on DoD — that's crucial. What I'd add: LiFePO4 really shines if you're looking at longevity maths.

Spot on. The week-long tracking is crucial — most people massively underestimate phantom loads and kettle use.

MSW works fine for basics — lights, kettles, that sort of thing. Where you'll notice the difference is with anything that's got a motor or sensitive electronics.

Spot on about working backwards. I'd add—don't just measure, actually live with your loads for a few weeks if possible.

Yeah, it's your battery's accountant really. Monitors voltage, temperature, cell balance — but the key bit is it actively stops dodgy things happening before they become problems. Mine's a Victron...