200W is the sweet spot for most narrowboats — enough for LED lighting, water pumps, and general leisure battery maintenance without needing to run the engine. Go bigger (300-400W+) if you want to minimise engine time or run a fridge continuously. This guide covers what you actually need, real UK prices, and the boat-specific decisions that don't apply to caravans or vans.
This guide covers 12V (or 24V) DC off-grid systems that charge your leisure and engine batteries — completely different from the mains-connected 230V AC "plug-in solar" kits covered elsewhere on this site. There's no G98 notification, no DNO, and no grid connection at all. If you're looking for balcony or garden solar for a house, see our plug-in solar legal guide instead.
What you actually need
A narrowboat solar setup has the same core components as any 12V off-grid system, plus one boat-specific extra:
- Solar panel(s): rigid or semi-flexible, sized in watts.
- Charge controller: MPPT or PWM, regulating the charge into your battery bank.
- Battery bank: your leisure battery (and often engine start battery too — see dual charging below).
- Deck fixings and cable glands: marine-appropriate waterproof fittings for running cable through the roof or deck without leaks.
- Inverter (optional): if you want standard 230V plug sockets rather than just 12V-native devices and USB.
Flexible or rigid panels for a narrowboat?
Unlike a static caravan's flat roof, narrowboat cabin tops and decks often have curves, hatches, and awkward angles — which is why semi-flexible ETFE panels are especially popular in this niche. They're thin, light, and can sit on a gentle curve where a rigid frame won't. Many are also designed to be walkable, which matters on a boat roof you'll actually stand on. Rigid aluminium-framed panels remain popular too where the roof is flatter, and are generally slightly more efficient and longer-lasting than flexible alternatives — the right choice depends on your specific boat's roofline more than it does on a caravan's.
Dual battery charging: a narrowboat-specific consideration
Most narrowboats run two separate battery banks: a leisure battery for lights, water pumps and appliances, and a separate engine start battery. A dual-battery charge controller splits your solar charge between both, keeping the engine battery topped up as well as the leisure bank — without it, you'd still need to run the engine periodically just to keep the start battery healthy. This is a genuinely boat-specific feature; you won't find it on caravan or general off-grid kits, so check specifically for "dual battery" or "DB" in the controller's name or spec sheet if you want this.
MPPT or PWM?
MPPT (Maximum Power Point Tracking) controllers harvest roughly 10-30% more energy than a basic PWM controller. This matters even more on a boat than a static installation, since roof space for panels is genuinely limited by the boat's width and layout — you can't just add another panel if you're short on power. For anything above around 150-200W, MPPT is worth the extra cost; several UK narrowboat installers now recommend it as standard even on smaller systems.
Victron controllers on a narrowboat: worth the money?
Look into narrowboat solar for long and the name Victron comes up constantly. Victron Energy, a Dutch company, does sell its own BlueSolar panels, but they are ordinary monocrystalline panels much like any other brand. What boaters actually rate is the Victron SmartSolar MPPT charge controller, which has become the default choice on liveaboard boats and with many marine installers.
Three things earn it that reputation:
- Bluetooth monitoring. The free VictronConnect app shows what the panels are producing, the battery voltage and a 30-day history, without climbing into the engine bay.
- Proper battery profiles. Charge voltages can be set for lead-acid, AGM or lithium (LiFePO4) batteries, which matters if you upgrade the leisure bank later.
- It works with a battery monitor. Paired with a Victron SmartShunt or BMV monitor you see a true state of charge, rather than guessing from voltage.
The model name tells you the size - the first number is the maximum panel voltage, the second the maximum charge current. On a 12V boat, a 75/15 suits up to about 220W of panels, a 100/20 about 290W and a 100/30 about 440W. Leave some headroom, because an undersized controller simply clips the output on bright days.
One limitation: a SmartSolar controller charges a single battery bank. It will not look after the engine start battery the way a dual-battery controller does (see dual battery charging above), so boaters who want both usually handle the start battery with a separate small charger or split-charge arrangement.
Is it worth it? For a liveaboard or continuous cruiser relying on solar for most of the year, yes - the monitoring alone saves a lot of flat-battery surprises, and Victron kit is widely known by marine electricians. For a weekend boat with a 100-200W panel, a decent generic MPPT controller does the same basic job for less money.
How much power do you actually need?
| Use Case | Recommended Panel |
|---|---|
| Battery maintenance / occasional LED lighting | 120-160W |
| Most owners — general leisure use, water pump, lighting | 200W |
| Minimising engine-running time, moderate appliance use | 300-400W |
| Liveaboard — fridge, multiple appliances, high demand | 400W+ (multi-panel array) |
A 200W panel typically produces around 67 amps per day in a UK summer (12V system); a 400W array roughly double that. Output drops significantly in winter, same as any solar system — plan for solar to supplement rather than fully replace engine charging through the darker months.
Real UK prices
| Setup | Typical Price |
|---|---|
| DIY 200W kit (panel + MPPT controller + cabling) | £150-£300 |
| Professionally supplied & fitted, 200W system | ~£600-£650 |
| Professionally supplied & fitted, 400W system | ~£1,000-£1,100 |
| MPPT upgrade on a basic system | +£100-£150 |
Supplied and fitted cost
If you would rather not drill your own roof, the supplied and fitted cost from a marina or mobile boat electrician is typically around £600-£650 for a 200W system and £1,000-£1,100 for 400W, as in the table above. Most of the gap over DIY is labour, deck glands and cabling rather than the panels themselves. Professional installation removes the hassle (and risk) of drilling into your own roof, and typically takes an installer a couple of hours. DIY is significantly cheaper if you're comfortable running cable and fitting deck glands yourself — narrowboat solar kits are generally designed for competent DIY installation, unlike more complex home electrical work.
The simplest option: a portable stand-mounted panel
If permanent fitting isn't for you — renting a mooring where you can't drill into the roof, or just wanting to try solar before committing — a portable panel on an adjustable stand is a genuine option some boat owners use. You place it on the roof or towpath, angle it towards the sun, and connect it to your battery bank via the same MPPT controller you'd use for a fixed panel. It's less efficient than a properly angled fixed installation but requires zero permanent modification to the boat. For more on portable panels generally, see our portable solar panels guide.
Recommended starter setup
200W Narrowboat Solar Kit (Panel + MPPT Controller)
A 200W kit is the most common starting point for narrowboat owners — enough for genuine day-to-day use without a large multi-panel array. Look for one that includes an MPPT controller and marine-appropriate deck glands as standard, since these are the parts most often sold separately at extra cost.
amazon Check Price on Amazon →If your cabin top has any curve to it, look specifically for semi-flexible ETFE panels rather than rigid ones. If you want to keep both your leisure and engine batteries charged from solar, look for a dual-battery MPPT controller specifically.
If you are weighing a boat against a fixed pitch, the static caravan guide covers the same living-space loads without the roof space limits, and the battery storage guide goes deeper on sizing the bank itself.
Summary — what to buy
- Most owners: 200W panel + MPPT controller, around £150-£300 DIY.
- Curved cabin top or deck: go semi-flexible ETFE over rigid.
- Want to keep both batteries charged: look for a dual-battery controller.
- Not ready to commit to fixed fitting? A portable stand-mounted panel works with the same controller setup.
- Don't want to DIY: professional supply and fit runs ~£600-£650 for 200W, ~£1,000-£1,100 for 400W.
Sailing a yacht or keeping a dayboat on a mooring instead? See our solar panels for boats guide.
Browse narrowboat and canal boat solar kits on Amazon UK.
🛶 Browse Narrowboat Solar Kits on Amazon →Frequently Asked Questions
Do I need a Victron controller for narrowboat solar?
No. Victron SmartSolar controllers are popular on liveaboard boats for their Bluetooth app and battery monitor integration, but any decent MPPT controller sized for your panels will charge a narrowboat leisure bank. For a weekend boat a cheaper MPPT controller is fine.
What size solar panel do I need for a narrowboat?
For basic maintenance charging and LED lighting, 120-160W is usually enough in summer. Most narrowboat owners settle on around 200W as a strong all-round choice. For heavier use or reducing engine-running to a minimum, 300-400W is more realistic, and liveaboards running fridges and multiple appliances often go beyond that with multi-panel arrays.
Flexible or rigid solar panels for a narrowboat?
Both are used, and the choice depends on your roof. Rigid aluminium-framed panels are more durable and slightly more efficient, and many narrowboat roofs are flat enough to take them directly or on adjustable frames. Semi-flexible ETFE panels are thinner, lighter, walkable, and better suited to curved sections of deck or cabin top where a rigid frame won't sit flush.
Can solar charge both my leisure battery and engine battery?
Yes. Dual-battery charge controllers, common on narrowboat-specific kits, split the solar charge between your leisure battery bank and your engine start battery, keeping both topped up without needing to run the engine as often. This is a narrowboat-specific feature not typically found on caravan or general off-grid solar kits.
How much does a narrowboat solar panel kit cost in the UK?
A DIY 200W kit with panel, MPPT controller and cabling typically costs £150-£300. Professionally supplied and fitted, a 200W system runs around £600-£650, and a 400W system around £1,000-£1,100. Adding an MPPT upgrade to a basic system typically costs an extra £100-£150.
Do I need an MPPT or PWM controller for a boat?
MPPT controllers harvest 10-30% more energy than PWM, which matters even more on a boat where roof space for panels is limited. For any system above around 150-200W, MPPT is worth the extra cost. Some installers now recommend MPPT as standard even on smaller systems given how much difference it makes in the UK's variable light.