How to install an 800W+ Solar system on a Canal Boat

Our system cost well under £800 including some high quality tilting solar mounts and extra large solar panels (425 Watts each).

Two Longi Solar 435WP panels mounted on Semi-Permanent Adjustable Mountings from Midsummer Energy
Panels Tilted for maximum power early in the morning

We did do a lot of planning and research when building this system and we will still be taking advice and measuring the performance (and reporting back our findings), but so far things are working very well and we are now disconnected from the expensive marina power.

You can see our parts list of items here, but this excludes some basic tools, like a good electric drill and a M8 tap set.

In the parts list I have included the suppliers details and in the articles listed below we explain the choices we made and why and also list any alternative suppliers and parts you may wish to consider.

For us a low profile system was essential as we are near one of the lowest bridges on the network where the Droitwich Canal goes under the M5 motorway. Using a tilting system we hoped to be able to harvest the most power when needed while maintaining a low profile.

Two Longi Solar 435WP panels mounted on Semi-Permanent Adjustable Mountings from Midsummer Energy
Low profile when folded flat

As you can see our plank and rear hatch are probably higher than the panels when lowered.

Over the next few months we will try to tilt the panels and record how much more power we can get during a normal day, but currently our first tests showed a 2-3 fold increase in power during the start and end of the day with the panels tilted towards the sun.

Coudy day with panels tilted towards the sun as reported by the Victron App.
Coudy day with panels tilted

Below is a list of the articles we wrote during the development of our installation:-

Planning for Solar Panels – Part 1
Planning for Solar Panels Part 2 – Panel Mounting Options
Planning for Solar Panels Part 3 – Types of Panels
Planning for Solar Panels Part 4 – MPPT vs PWM solar controllers
Planning for Solar Panels part 5 – Cable sizes, lengths and resistance.
Planning for Solar Panels part 6 – Panels in Serial or Parallel
Planning for Solar Panels part 7 – Buying the cable and Circuit breakers
Planning for Solar Panels part 8 – Buying Solar Panels and Mountings
Planning for Solar Panels part 9 – Wiring
Planning for Solar Panels part 10 – Drilling, Tapping and Fitting

Please read our Safety Disclaimer

Adding rubber feet to solar mountings

A simple fix to the roof getting scratched by the tilting system for the solar panels was to add some rubber feet, I used Adam Hall Hardware 4903 M4 Rubber feet which are 9mm tall and 20mm wide.

Feet held on with small stainless self tapping screws
Small increase in hight, but saves the paint

I also replaced the nuts of the arms with the Nylock versions, so save them vibrating loose.

Our Canal Boat Solar Panel Kit Parts List

After much reseach we have built up a kit of parts to install our 870W solar panels on the roof or our narrow boat, I will need to add a few cables and some mounting wood plates.


Image Description Price

Longi Solar 435WP Longi Solar 435WP Black Frame PV Module LR5-54HTH-435M

Selected as they have a 3.2mm glass rather that the much cheaper 1.6mm and provide almost the maximum output when combined for the Victron SmartSolar MTTP 100|50 MPPT solar controller.
Ordered 2 from City Plumping, they deliver free next day from stock, for £91.76 (£110.11 inc VAT) each. (Prices have dropped since)
£220.22

Semi-Permanent Adjustable Mounting Set for Narrow Boats

Ordered and built to size by Midsummer Energy
2 needed 1 per panel installed at £98.00 each

£196.00

Victron SmartSolar 100|50 Victron SmartSolar MTTP 100|50

Ordered from Nomadic Conversions eBay shop
£220.00

Solar PC Cable 

25m Red and 25m Black 6mm Solar PV Cable from Superlec Direct at £1.19 per meter.
£59.50

WYLEX 100A DP ISOLATOR WITH ENCLOSURE (321FR)

Wall mounted 100 amp isolator from Screwfix Direct
£20.49

Water proof cable access

IP68 Waterproof cable access, designed for Solar Installations
Scanstrut DS-HD6-BLK Horizontal Double Cable Seal – Black 
£9.99

Circuit Breakers / Fuses

RED WOLF 60A Circuit Breaker from Amazon.co.uk

£14.99

Solar Connectors

See video on installing MC4 connectors
4 off MC4 Connectors from Superlec Direct at £1.74 each

£3.48

Misc Bits

1 off 6.1mm Drill bit
1 off M8 Tap
16 off  M8 Allen Flanged Bolts
16 off M8 Nylock Nuts
Tube of Sikaflex etc

£20.00

  Total (Inc VAT) £768.15

There will be some additional cost from Steve for his time, so I would expect this to have cost approx £1000.00 when complete, but cost have been falling even over the past 6 months.

Also see
Planning for Solar Panels – Part 1
Planning for Solar Panels Part 2 – Panel Mounting Options
Planning for Solar Panels Part 3 – Types of Panels
Planning for Solar Panels Part 4 – MPPT vs PWM solar controllers
Planning for Solar Panels part 5 – Cable sizes, lengths and resistance.
Planning for Solar Panels part 6 – Panels in Serial or Parallel
Planning for Solar Panels part 7 – Buying the cable and Circuit breakers
Planning for Solar Panels part 8 – Buying Solar Panels and Mountings
Planning for Solar Panels part 9 – Wiring
Planning for Solar Panels part 10 – Drilling, Tapping and Fitting

Planning for Solar Panels part 10 – Drilling, Tapping and Fitting

Two days of wind and rain, and for today the forecast looks good, everything is now ready for an 9am ish start.

I showed Steve what we had done so far, we then made some measurement to find the best position for the cables to exit through the roof in to the Waterproof Solar Cable Entry Gland I had purchased on Amazon.

The first hole we drilled up a 6.1mm hole from inside the boat through the wooden batten and then out in to the roof, the position was perfect. Now from the top we drill down a second hole next to the first, and then we widened them both with a 10mm drill and then used a 12mm drill is used to slightly countersink the holes.

I push the cables up through the holes to Steve and then with a sharp chisel cut a slot in the wooden batten so the cable can lay flush ready to put the skirting boards back on.

Cable Gland ready to stick down

On the roof top the cables are feed through the cable glands and the surface where we are going to fit the housing was cleaned, then it is out with the Sikaflex 291i Marine Sealant and Adhesive, some is put around the cables as they pass through the roof to provide an extra seal and then around the flat base of the underside of the plastic housing, this is then carefully placed on the roof and held down with a weighty 5 litre water bottle while the adhesive is left to set.

Time to put the panels on the roof and find the positions for the feet. Once we have checked and rechecked the position (Steve has a the knack of doing this by eye very accurately), we then mark the positions of the feet with a marker pen, move the panel out the way and we remove one of the feet to check the positions again.

Steve Cowham – Drilling and tapping

We are using M8 bolts. so once we are sure we have the positions correct we drilled a 6.1mm hole and then tap this with an M8 tap, we are using 8 bolts to hold down each panel, so this process is repeated another 7 times..

We now remove the arms from the panel, leaving the 90 Degree angle bracket still attached so we keep the final position (See picture below)

The kit comes with some pre-cut rubber strips that sit under the aluminium feet, we use the Sikaflex to glue these down and then on the tops side of each apply another layer of Sikaflex remembering to put some in the drill holes before positioning the feet and bolting down them down tight. This squeezes out any excess Sikaflex which needs cleaning away with a bit of kitchen roll.

Once all four arms are attached we can move the panel into position and re-attach it to the arms. We do find one small problem with the design of the arms, in that they have a very sharp corner that easly scrapes away the roof paint.

I will have to find some rubber feet for this, but for the moment some tape will have to do. (Note: See added rubber feet)

We are now ready to do the second panel which after the learning curve of the first goes very smoothly.

Two solar panels fitted

At this point all that is left is the check I have the wiring plan correct and then fit some MC4 connectors to the end of the cables and make another cable to join the two panels together in series.

I made a sort video/write up a while ago about fitting these connectors << link to article here.

I also added a Victron Energy VE.Direct Smart Dongle (Bluetooth adapter) to the MPPT so I could configure it and monitor its performance.

Remember this picture…

Now that the system should be up and running, I would see 70 Volts on the Victron App but no Amps which seemed a little odd. I traced and checked the cables from the solar panels back to the MPPT controller and finally noticed we had connected the cable from the battery to the bolt fixing the 60A breaker to the back plate, after swapping this around, we had power, not a lot as it was getting late, but proper power.. very exciting.

I left the boat unattached from the shoreline power overnight so we would have some space for the solar to do some battery charging the next day.

This is a screen shot from the Mac app for following day, and it shows the panels making 670w of power, as you may notice from the graph it is a cloudy day but the system had managed an amazing 710W earlier. with in 3 hours with the panels tilted towards the sun we had replaced our nights usage.

Tilting the panels – does it help?

I will generate some more accurate figures once I have had a chance to play, but it seemed that I could easily triple the power output early and late in the day by tilting the panels towards the sun.

Very low profile when folded flat

Probably the best feature of this mounting system, is that when folded flat they take up very little of the view and fit nicely over our vents. For more information on these and the other mounting systems we looked at follow this link

In the next few days I will compile a find parts list with supplier details and costs.

My thanks to all the suppliers and advice I was given getting this all together and Steve Cowham for is work, If you need some work done on your boat book him early he always has a backlog, you can find his contact details on our Useful Contacts page.

Also see
Planning for Solar Panels – Part 1
Planning for Solar Panels Part 2 – Panel Mounting Options
Planning for Solar Panels Part 3 – Types of Panels
Planning for Solar Panels Part 4 – MPPT vs PWM solar controllers
Planning for Solar Panels part 5 – Cable sizes, lengths and resistance.
Planning for Solar Panels part 6 – Panels in Serial or Parallel
Planning for Solar Panels part 7 – Buying the cable and Circuit breakers
Planning for Solar Panels part 8 – Buying Solar Panels and Mountings
Planning for Solar Panels part 9 – Wiring
Planning for Solar Panels part 10 – Drilling, Tapping and Fitting

Safety Disclaimer

Planning for Solar Panels part 9 – Wiring

It has been a long time since September last year when we where about to install our solar panels, we had almost all the parts ready (Except a few minor bits and bobs), now all we just needed a clear weekend for both me and the weather.

It is now the Easter weekend 2024 over 6 months later than expected, I have booked Steve Cowman to help as these panels as they are very very large and it has been over 30 years since I have tapped a hole…

But before Steve came to help, I had to route the wires back to the engine bay where I was mounting the MPPT Solar controller. On the Black Prince boats of this era they had used some skirting board at the bottom and top of the walls, so I removed the upper boards and found a wooden batten which the skirting board was screwed to, each side of this was two approx 1 inch / 25mm layers of polystyrene as insulation.

Note: Interesting thing about polystyrene is that it has a bad effect on PVC (Polyvinyl chloride) and over time it eats into the surface of the PVC making it brittle. A lot of wires used in boats and our homes are PVC coated or includes PVC as this makes the plastic coating more flexible.

see https://youtu.be/fArXX-u7uxs


Using a knife I cut out one layer of the polystyrene foam below the wooden batten to create a channel in this I placed some flexible nylon conduit, in which I run the solar cables back to my services cupboard at the back of the boat.

In the services cupboard I installed an 100 Amp dual pole isolator.

The cables from this then routed into the engine bay and to the solar controller PV in connections.

The red arrow will become important later, best to say this board is unfortunately mounted in a very hard to reach place.

Next Sonia (the super wife) and I moved the panels on to the grass and mounted the long aluminium slotted bars to the back of the panels as near to the edges as possible, then about 20cm in from the ends we attached the legs. unfortunately this was as far as we could go as the wind was making it almost impossible to move the panels. So for the next couple of days we had to wait for the wind and rain to stop long enough for us to complete the job.

Also see
Planning for Solar Panels – Part 1
Planning for Solar Panels Part 2 – Panel Mounting Options
Planning for Solar Panels Part 3 – Types of Panels
Planning for Solar Panels Part 4 – MPPT vs PWM solar controllers
Planning for Solar Panels part 5 – Cable sizes, lengths and resistance.
Planning for Solar Panels part 6 – Panels in Serial or Parallel
Planning for Solar Panels part 7 – Buying the cable and Circuit breakers
Planning for Solar Panels part 8 – Buying Solar Panels and Mountings
Planning for Solar Panels part 9 – Wiring
Planning for Solar Panels part 10 – Drilling, Tapping and Fitting

Safety Disclaimer