Solar Energy System of the Month:

Solar Boats Turn into Tourist Attractions

By Rolf Hug

Summer, Sun, Sea-a combination that causes hearts to beat faster, even in the photovoltaic industry. A high tech company in Baden-Wuerttemberg has been building solar powered boats since 1998 with growing success.

The Solar Shuttle "RA 82"- the largest solar ship in the world. Built by Kopf Solardesign in Sulz-Bergfelden. Owner: Alster Touristik Ltd., Hamburg.

solar shuttle RA 82
Photo: Kopf Solardesign

"Alster Sun"- World Wide Number One

The largest solar boat in the world began operating on the Alster River in Hamburg on May 23, 2000. The almost 27 meter long and 34 ton "RA 82", which was baptized "Alster Sun", glides on the river without any noise at up to 15 kilometers per hour. While cruising in front of Hamburg landmarks, the ship itself has become an attraction. 40 tons of stainless steel and a dainty roof of solar modules glitter in the sun.

The boat can hold up to 120 passengers for excursions and charter tours. The "Alster Sun" reaches a speed of 5 kilometers per hour just from solar power. If it has to go faster, the rest of the energy comes from batteries. The power reserves of the 80 batteries (2340 ampere-hours at an operating voltage of 80 volts) last for at least 12 hours or for a distance of 120-160 kilometers. The boat is powered through two 8-kilowatt marine screw propellers and casts off five times a day.

The boat looks quite impressive when bound outward: the shining silver metal and the arched solar generator emphasize the futuristic character of the tourist boat. The construction appears especially elegant and pretty from the bank of the river, but quite a few things are offered to the passengers.

On board, the solar modules create a fascinating play of light, shadow, and transparency. They also protect the passengers from weather conditions; the passenger room can be closed when it is raining. When the weather is inclement, the electricity from the 80 gel batteries is used. A complete set of chairs and tables belong to the furnishings as well as sanitary facilities and a kitchen to prepare food for the guests.

The outstanding designs of the boats built by Kopf, which were presented in the "National Design Museum New York" and the "Design Museum London", have won numerous awards.

solar boat design
Photo: Kopf Solardesign

The boat details are specially designed according to the desires of the purchaser. The top goal of the designers was to create a symbiosis of technology, ecology, and design. Indeed, the "Alster Sun" additionally shines, just like her sisters from Swabian Balingen, with her invisible virtues. There are advantages in addition to the quiet propulsion: neither oil nor gasoline flows into the water. And even in winter, when the boat is docked, the environmental balance is still positive. The floating solar power station then feeds the electricity into the grid of the Hamburg Electric Company.

Helio & Co: Multipurpose Boats

Kopf Inc. employs approximately 360 workers nationwide in Germany in the areas of heating, sanitation, and solar technology. The dockyard located at the edge of the Swabian Mountains won even more prominence with the contract for the 1.3 million mark "Alster Sun". The ship that was built in Balingen supplies the evidence, that solar technology in shipbuilding also works on a large scale. In the mean time, the number of sites where the boats are used and the varieties for which purposes they are used have grown further. The company even offers ships for private use as well as solar ferries in many different sizes.

Solarshuttle RA 66
Solarshuttle "RA 66".
Photo: Kopf Solardesign

The ship "Helio", named after the Greek
Sun God, shuttles between Gaienhofen, Germany, and Steckborn, Switzerland, on Lake Constance. The 20-meter ship can
hold a maximum of 68 people and 15 bicycles.


The weatherproof RA 66 ship is fit for service for six to eight hours even when the sun doesn't shine, depending on the whether it is traveling at a speed of 10 kilometers per hour or at its peak speed of 15 kilometers. The generator with 52 modules produces 4.20 kWp; 24 batteries with an operating voltage of 48 volts ensure the needed reserve of 900-ampere hours. Another boat from Kopf Inc. serves as a solar hotel shuttle on Lake Lucerne. Solar boat tours are offered on the Danube in Ulm, and small, emission free ships are used to control the quality of water of reservoirs that supply the population of Bavaria and Baden-Wuerttemberg with drinking water.

Pure Enjoyment of Nature

For environmentally conscious people the technology is interesting for private use as well. The almost 4 meter Catamaran "Sol 10" is constructed to hold 5 people. An integrated sun deck and ladder ensure carefree swimming fun. The boat can be purchased, complete with an installed battery charger, for approximately 20,000 marks. The beautifully formed modules with a peak output of 150 watts arch over the hull that is made out of glass fiber reinforced plastic. The range of the boat amounts to 7-8 hours, depending on the equipment; speeds of 6-9 kilometers per hour are possible.

Only a small part of boat owners use solar powering. The clean power has definite advantages: they are allowed to navigate through water protection areas that are taboo for loud and foul smelling diesel boats.


Catamaran "Sol 10": direct current powering from 550 to 1600 watts. No drivers license needed, unsinkable, and easy to use.


Catamaran "Sol 10"
Photo: Kopf Solardesign

The solar boats from Swabia are a fine thing for tours or excursions, for swimming or fishing: no noise, no exhaust, and absolutely no water pollution. The felicitous design adds considerably to the fact that solar technology will also prevail for the use on the water. A trip with a solar shuttle is a must for solar friends and the right time is during vacation.

Material and photos: Kopf Solardesign, Stützenstraße 6, D-7212 Sulz-Bergfelden.

Solarserver Editorial Staff: Rolf Hug

Translation: Mary Meier


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