Solar power can be one of the boater's best friends. How does it work and what are the best gadgets out there?

The ability to turn the sun’s rays into usable power might seem like a form of modern alchemy but the technology is not new. It revolves around the use of a photovoltaic cell, which turns light (‘photo’) into electrical energy (‘volts’).

Solar power boat

The solar-powered 'Planet Solar' is an amazing boat.

A photovoltaic, or PV cell, is made up of two layers of silicon, the lower of which contains too few electrons and the top too many. In its idle state, there is no traffic of electrons between these two layers and therefore no current flow – but when light (or more accurately, the stream of photons of which light is comprised) hits the device, it gives up its energy to the atoms in the silicon. The electrons in the lower layer then ‘jump’ the barrier to the top, creating a circuit and generating DC electricity, which increases in tandem with the quantity of light hitting the cell.

Obviously, the cells themselves only produce a tiny amount of power, so a great many of them are connected together to form solar panels - and it is products of exactly this kind that you see on the shelves at your local chandlery.

Solar power: flexible solar panel

A flexible solar panel.

There are three basic types of PV panel.

(1) Monocrystalline cells, which are heavy and expensive but very efficient and well suited to use on large boats.
(2) Polycrystalline cells, which have a speckled appearance and are a touch lighter, but still require rigid mounting and orchestration toward the sun for best performance.
(3) Amorphous cells, which use a very thin film of silicone and can be flexible enough for flush-mounting on a variety of curved boat surfaces.

Naturally, the type of panel and the PV area you require will be denoted by the demands you expect to place upon it. If you use a range of domestic appliances like a fridge, fans, pumps and computers, you need a generous battery bank and sufficient solar power to keep it charged. But modern solar power is about much more than just trickle charging your batteries, as the following selection proves…


The handy Solar Gorilla providing useful solar power

The handy SolarGorilla providing useful solar power.

Powertraveller SolarGorilla

Powertraveller has been producing portable energy solutions for a long while now and its range-topping SolarGorilla is one of the best. It works via two PV solar panels in a tough outer casing.

Radar arch mini top-up solar panel

Radar arch mini top-up solar power panel.

Smaller than a piece of A4 paper, this relatively lightweight unit hinges open to generate enough surface area to power not just your smart phone and iPad but also your laptop computer. It comes with plenty of adaptors, plus a 5V USB outlet for the connection of more modest gadgets. While you may have to supplement it with the PowerGorilla when the sun refuses to come out, successful trials by aid agencies and emergency services suggest that this is a very effective tool.


Mini top-up solar panel

There’s nothing revolutionary here, just good, clever thinking. A mini panel mounted on top of the radar arch (as pictured here on the Stingher 800 GT) means uninterrupted access to the sun. While its output is not vast, it doesn’t need to be. On a relatively small open boat, used in tandem with low-energy LED nav and deck lights, it’s easily enough to keep your battery topped up while you get on with enjoying your day.


Solar power antifouling solution

This solar power charger does the job of antifouling paint.

Solar power antifoul

Electronic antifouling is a clean and modern way of keeping your hull clean, but it does require a constant (albeit modest) feed from your battery bank. That’s why Ultrasonic has introduced the Solar Charger. It’s basically a box that sits between your solar panels, your battery bank and your Ultrasonic Antifouling system. The intelligent unit keeps your battery in good health and provides the Ultrasonic system with the correct amount of electrical power, enabling those without a regular power supply to employ the antifouling system without concern. It can operate with wind generators as well as solar panels and it helps keep you protected against things like overload and short circuit, as well as current drain from the battery to the solar panels overnight.


Solar powered outrigger

The marine equivalent of the electric pushbike; a solar powered attachment for your kayak.

Solar powered outrigger

I guess this is probably the marine equivalent of the electric pushbike. Known as the SPK-1, it’s basically an outrigger attachment that enables you to propel your kayak without having to paddle. You simply connect it to any medium or large kayak and the solar energy produced by the PV array powers a battery that runs a small 12V motor. In fairness, I’ve never met a kayaker who found paddling a chore (which suggests this may well be a solution to a non-existent problem) but it shows how hard marine designers are now working for ever more ingenious ways of using solar power.


Solar powered Casio watch

Solar powered watch from Casio.

Solar powered watch

Quite why there is still such a thing as a battery-operated digital watch is entirely beyond me, because it is exactly the kind of constant-use, low-draw gadget that shows solar energy off at its best.

Despite minimal PV space and the ever-increasing armoury of features on the modern sailing watch, from radio-controlled accuracy to barometric pressure, temperature, compass bearing and tidal data, these things simply go on forever.


Solar powered vent

Why plod on with an inanimate mushroom vent or a switched unit that connects to your battery bank when you could fit a standalone, wire-free, solar-powered device like this.

Solar vent

The handy solar powered vent.

Marine models tend to be constructed from stainless steel and the best are capable of providing 24-hour ventilation courtesy of an inbuilt rechargeable Ni-cad battery, which keeps it ready and willing even at night. With the capacity to switch between intake and exhaust modes, a vent like this is an ideal accessory for a boat.


Solar powered boat

Okay, so it’s not exactly a gadget, but ‘Planet Solar’ is a hell of a boat. The fact that it is capable of circumnavigating the globe with nothing but the sun as a fuel source pays ample testament to just how efficient modern panels and battery management systems are becoming. Despite measuring 31 metres in length and weighing 89 tonnes, a PV surface area of 516 square metres generates 93.5 kW, enabling this twin-hulled boat to cruise at around five knots with up to 60 people on board. How’s that for a glimpse into the future?