Roaming Solar

by Adrian on January 24, 2015

We’re currently in the Caribbean roaming the seas in a very self sufficient manner. We are making our own water, generating our own electricity, shopping locally and living quite cheaply and well. (We’ll all be reading the Guardian , not washing and wearing dreads soon if we carry on like this!)

(not much chance of that)

Coachroof Solar PanelsOne little modification I made before leaving Las Palmas which is helping considerably was replacing the two 65W factory supplied solar panels built into either side of the coachroof with more efficient 100W mono-crystalline ones. This was a relatively simple job, so I thought I’d make it a bit more challenging by installing new cabling and a decent waterproof deck socket for a third roaming solar panel. I also updated the charge regulators with decent Victron MTTP ones as I was appalled at how little electricity the original solar panels and regulators were making.


The new panels produce between 4-5 Amps each in sunshine, so in conjunction with the arch panels, we have a maximum of 570W of solar power. In practice, we easily produce 15+ Amps for 6-7 hours during the day, so are producing about 130Ah from solar each day.

The latest generation of flexible solar panels use monocrystaline technology to make them 21.5% efficient. Amazingly, that is as efficient as my rigid glass panels on our arch, at far less weight. These new flexible panels are idea for on-deck installation as they can be stepped on (albeit carefully) and can be bonded to a curved surface.

You have to shop around carefully though, as many companies are still selling older technology units and calling them modern. You might as well get the best thats available, as you are expecting them to have a long life.

These are the typical specs you are looking for:

100W monocrystalline flexible solar panel

    Peak Power: 100W
    Voltage: 17.8V
    Open Circuit Voltage: 21.6V
    Short Circuit Current: 5.97A
    Current: 5.62A
    Tolerance: +-5%
    Efficiency: 21%
    Dimensions: 1050x540x3mm
    Weight: 1.7 kg

I found these originally at where they are £329, but by shopping around found another supplier in the UK that was selling the same panels for £215 each.

The problem is that all these panels are OEM models, and there are no brand names commonly used, so comparison is quite difficult. Use the specs, rated wattage, efficiency and panel size to compare. (Power and efficiency being the key!)

Suppliers generally add their own cabling to the panels, so make sure the cables exit where you need. Usually they exit on top, but occasionally some exit underneath. Underneath sounds good for a deck install, but you usually need a large hole for the terminal block, and large holes in a boat aren’t a good idea.

We know this from experience as the first set installed by Allures had rear cable exits and after a season in rainy Brighton we had water seeping in the coachroof cut-outs and dripping inside the saloon. Fortunately they recognised their mistake, removed the old panels, fibreglassed up the holes and installed panels with top cable exits and small well sealed deck glands

The new panels were slightly smaller as they are rectangular instead of having one angled end, so instead of leaving an ugly white gap I bought some self adhesive carbon fibre veneer to make the job look better. I used Evostick WetGrab bonding to secure them flat and flush to the coachroof and screws around the outside to stop the edges lifting.


Since these panels were so reasonably priced, I bought a third one and have is as a roaming panel. The sun never shines on both sides of the boat at once so only one of the coachroof panels generally works at a time. The panel has metal grommets in each corner, so I use strong re-usable zip ties to hang the panel from the sunward coachroof handrail when sailing so it is at an ideal angle for the sun or on top of the sailbag when at anchor to provide an additional 4-5 Amps of power.


I’ve extended the cable and sealed the joins with adhesive heat shrink. The deck connector is a good quality waterproof gland I found from a specialised UK auto supplier.

Normally, deck connectors are either awkward screw in stainless steel types or flimsy 12v cigarette lighter sockets. This one can handle up to 16 Amps, has a positive locking mechanism, is fully watertight and has a blanking cap for when not in use.

AquaSignal Connector

The solar panel taste to the handrails and pointing towards the sun when sailing:
Roaming Panel In Use

The solar panel on the sail bag when at anchor:
Roaming Solar

Victron Blue Solar MPPT solar regulatorThe Victron Blue Solar MPPT solar regulator. This guarantees you get the most power from your panels and is a perfect size for this type of panel. Use one per panel. Cost – about £80 each.



So… we’re sitting here at anchor, the sun is out and I’m able to run the water maker, computers, fridge and everything else and still have full 780Ah batteries by sundown. During a day we can produce 100-120l of water to top off the tanks. Especially after washing day.

Overnight we’ll eat into the batteries with the fridge, freezer, anchor lights, iPad charging etc so need to run the genny for a couple of hours first thing in the morning during breakfast, but it is all quite sustainable. Nights are long here (12-13 hours), so the batteries go down to 640Ah overnight and are back up to around 750Ah with two hours generator use.

Whilst the generator is running and charging the batteries it heats the water tank, we use the kettle, have toast, have coffee, charge whatever we can and even run the washing machine.

One last tip… Since the wind is invariably out of the east in the Caribbean, and you always face into it at anchor, your stern panels need to be able to tilt downwards so you can angle them westwards towards the sun…

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