Anyone running solar on a narrowboat with an EV on the towpath — how are you managing the charging?

Bit of an odd one this, but bear with me. I've got a narrowboat moored semi-permanently at a rural site that also has mains hookup (16A), and I'm trying to work out whether it makes sense to add solar on the roof to reduce how much I'm pulling from the hookup — especially for when I've got the little Nissan Leaf parked nearby and want to top it up without hammering the electric bill.

Currently running a fairly modest setup: 400W of panels feeding into a Victron SmartSolar MPPT 100/30, with a 200Ah Fogstar lithium leisure battery bank. That handles the boat's 12V loads fine — lighting, water pump, a bit of fridge — but the moment you start talking about pushing anything into an EV, even at 3kW, it all feels a bit optimistic given the roof space I've actually got.

Has anyone actually done this properly? I'm wondering whether a shore power–solar hybrid approach through something like a Victron Multiplus makes sense, so the solar offsets the hookup draw rather than trying to do it all standalone. Or am I overcomplicating something that just doesn't pencil out on a narrowboat roof?

Reply by Dizzy83:

@AnneOliver Sounds like a cracking setup actually! I'm doing something similar-ish — 800W of panels on the roof feeding a 200Ah lithium bank, and I've got a Zappi charger on an outbuilding at our mooring which can divert solar surplus before pulling from the grid.

The key thing I'd say is watch your diversity of loads carefully. Boat systems, domestic stuff, and EV charging can easily overwhelm a 16A supply if they all kick in simultaneously. A good energy monitor (I use a Shelly EM) really helps you see where the pinch points are.

What EV have you got? Some are better than others at accepting variable charge rates — useful if you're trying to throttle down to whatever the solar is actually producing at a given moment rather than hammering the hookup.

Reply by LDVProject:

@AnneOliver Interesting situation! One thing worth considering is a decent battery monitor (Victron BMV series is popular) so you actually know your state of charge before deciding whether to divert solar into the EV or keep it for the boat systems overnight.

If you're on a 16A hookup you're looking at roughly 3.5kW max anyway, so even a basic EVSE will work fine for overnight charging when solar's not contributing. The key is sequencing — boat batteries topped up first, then any surplus hits the car. A Cerbo GX with ESS can handle that logic automatically if you go down the Victron route. What battery bank size are you working with on the boat? That'd help work out whether your solar's genuinely surplus most days or whether you're regularly drawing from the grid anyway.

Reply by Paul1999:

@AnneOliver Sounds like you're in a similar position to me last summer. One thing I'd add that hasn't been mentioned — have a good think about your EV's minimum charge rate. A lot of cars won't accept less than 6A on AC charging, which is already 1.4kW, so if your solar and batteries are marginal you can end up with the car simply refusing to charge at all rather than trickle-charging overnight. I ended up using a simple timer on my EVSE to only charge during peak solar hours rather than trying to be clever about it. Crude but reliable! Also worth checking whether your 16A hookup is shared with other moorings — that can catch people out when neighbours are running their own kit simultaneously.

Reply by CraftyWelder:

@AnneOliver Worth thinking carefully about your EV's minimum charge rate before committing to anything. Some cars (Nissan Leaf, older Zoes etc.) will flat-out refuse a charge session if the available current drops below a certain threshold — usually around 6A AC. If you're pulling from the boat's inverter while the solar's doing its thing and the batteries are partially depleted, you can end up in a frustrating loop of failed charge attempts.

A proper EVSE with adjustable current output (the Rolec or Hypervolt units let you dial it right down) gives you much more flexibility to match what you're actually generating. Pair that with a decent MPPT controller that has load output control and you can prioritise the boat's bank before anything goes to the car. Keeps things sensible on cloudy days.

Reply by MountainBarry:

@AnneOliver The hybrid approach is where it gets interesting. My cabin setup taught me that the crossover point — when solar surplus tips into genuinely useful territory — shifts dramatically with seasons. July you'll feel flush, January you'll be rationing.

What I'd seriously look at is a Victron MultiPlus with PowerAssist. It can blend your 16A shore supply with battery/solar output, meaning you're not fighting the shore hookup's current limit when the EV is pulling hard. Effectively lets you punch above your metered allowance without tripping anything.

The narrowboat hull is also decent real estate for panels — I've seen folk stack 600W+ across the roof without drama.

The honest question though: how many miles are you actually doing? If the EV barely moves, the maths on extra solar kit takes a long time to stack up.

My shepherd's hut taught me that the moment you think you've got enough solar for everything, the clouds roll in and your EV sits sulking on 12% for three days — so I'd seriously look at a Victron MultiPlus-II to intelligently blend your 16A hookup with whatever the panels contribute, rather than trying to go full solar-hero on a British towpath in November.