PV panels on the deck of MS Turanor PlanetSolar

Will solar float your boat?

PlanetSolar flew the flag for photovoltaic technology with its round the world cruise, but also provided a shot in the arm for solar boats.

It all began as a bet. After much discussion, Swiss eco-adventurer Raphael Domjan and German businessman and solar advocate Immo Stroher combined finances and ideas to produce the largest solar boat in the world – the MS Turanor PlanetSolar.

The surface of the 35m boat is covered by over 500m2 of PV panels that supply power to a 120kW electric motor that drives two propellers, one on each hull, which can drive the boat to a top speed of 14 knots (26km/h). Storage is provided by a vast array of lithium-ion batteries. The boat, along with its four-man crew, glided from Monaco harbour on 27 September 2010 and, 584 days later, having visited 28 countries, made its triumphant return.

Despite the success, developing a solar shipping industry was not at the forefront of the team's ambitions. "The first thought behind this project was to demonstrate the reliability of PV products," Pascal Goulpie, PlanetSolar's CEO and co-founder explains. "If we can covert the solar energy that the Earth receives each day even with low efficiency at a good price we can supply a lot of the energy demand for humans.

"When we launched this project in 2005 it was because we were disappointed that we were not using more PV to generate energy and also that PV was suffering from such a poor reputation – it was [deemed] expensive, inefficient and not very reliable. So the first aim was to demonstrate the capability of current PV technology."

The word 'current' is crucial: "It was important to build the boat from materials that were readily available on the market," says Goulpie.

One by-product of the venture has been to put the role of solar power in the maritime sector on the public agenda. "When I started the project we were not wealthy and not well known," Goulpie continues. "Our objective was not to change or shape the market for shipping; we didn't have the influence. The intention was never to try and prove that the future for the marine industry should be based entirely on solar power.

"For me it is all about using the right energy in the right place. Of course on the seas wind is very important and has been used for centuries, but for me, clearly, the sun is also an important energy source. Now there is growing interest amongst the marine sector for solar energy, which is good. And if PlanetSolar had a small part to play in generating that industry I am very proud."

From the outset Goulpie and his team had full confidence in the key technologies, and that was borne out as the project progressed. There were no problems with reliability, conversion, storage or production of mechanical energy from solar energy. "We didn't need to learn because I was sure, but it confirmed what we already knew about PV technology, that it was capable of powering a huge vessel round the world."

That is not to say that running a solar boat was without its challenges. The average consumption had to be limited to 20kW, which required careful planning of usage. "When working with PV technology it was important to think carefully about how much energy was used and ensure there was no waste. On board we used low-energy devices."

One area that caused some mechanical problems was the propeller. It was originally the plan to install a surface propeller, which was a high-efficiency solution and already commercially available, but it proved to be unreliable. "It was not widely used at this time and unfortunately we had to replace it with a conventional one," Goulpie says. "Twice we had a problems concerned with the pitch control of the blade on the surface propeller. It was a nice product but too complex. We couldn't afford to have any mechanical problem when we were trying to prove the reliability of the PV technology."

Bright future

With the world tour complete, the team was determined that the boat should not be consigned to a museum. "After the world tour it was important to have a boat that was able to enjoy a second life," Goulpie adds.

That second life is a collaboration with the University Of Geneva. Led by Professor Martin Beniston the boat will cruise the Gulf Stream collecting measurements about climate impact. "The world tour was an adventure," Goulpie says. "[But now] we have a boat with fully functioning and reliable tools. It is unique in that it is large, under its own power and has zero emissions. With a sailing boat you are dependent on wind force and direction, but with this you have the environmental benefits of a sailing boat but with its own engines."

Although developing a thriving maritime solar industry was not the goal, PlanetSolar's round the world adventure may prove to be the catalyst for future environmentally friendly shipping.

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