Opposite: the first J/88e in Annapolis. There can’t be many yacht owners who would not be attracted by the idea of replacing that messy diesel with electrical power – sail-mounted solar panels, efficient electric motor plus lightweight lithium batteries. Only a small regulator is needed on mid-sized installations (far left). Left: the mainsail goes up on Daniel Ecalard’s Open 50 ahead of the rough 2014 Route du Rhum, during which her solar installation performed flawlessly
none of which seemed to affect charging capacity.
There was a lot more work to do, however. Highly conductive carbon yarns had to be replaced with black aramid, diodes had to be incorporated to prevent unwanted polarity switching between the two sides of the sail, circuit breakers were fitted at the tack, alternative bonding sys- tems were required, plus we had to identify the best way to wire up the sail and bring electricity down to the photovoltaic regu- lator inside the cabin, then feeding it into the battery system via a selector – or via a bus for boats using an electric engine. We have been experimenting with two types of thin solar cells for the ‘Power Sails’ system (aSiGe and CIGS). Both films are cooked using one bar pressure at 120°C during the lamination process in our oven. We also looked carefully at DSSC, CdS/CdTe, OPV cells and some other very new technologies, but we do not feel confident using them at this point. We are expecting other breakthroughs soon; in the solar industry things seem to evolve very fast, perhaps at twice the rate according to Moore’s Law. Every indus- trial country is developing new thin film prototypes, many of which will become commercially viable in the next few years. (Surprisingly, China is not yet among the leading nations in this particular sector). To qualify as a thin solar film for sail- making, the film should be 65µ-150µ thick giving the finished solar film+sail material a thickness of 0.5-0.75mm, with a weight of 200-400g/m2
; this after full encapsula-
tion into a sail laminate or bonded over a woven material like Dacron.
And the small bending radii of the best thin solar films will now allow a tight wrap around a pencil. In other words, the thin flexible films used in Power Sails are nothing like the films used for typical camping or boating applications. Those ‘traditional’ recreational panels are at best semi-flexible pads weighing 2-3kg/m2
and
with 30° maximum allowable bend. Every technology has its pros and cons. Some solar films work only in direct sun- light, some work with partial luminosity, others work well with artificial interior lighting (shopping malls, hospitals and so on) and do not do so well outdoors. Some emit heat when operating, some are very
moisture sensitive, some are good for high voltage while others offer better output with low voltages. For the Power Sails system we choose the film and cell solution best suited to each application. The internal circuits we build use a highly flexible thin copper-composite. Armoured solar wires run down the luff of the sail, just as an over-the-headboard leech line runs to the tack. All the junction boxes and connectors are IP68 rated (IEC stan- dard 60529) hence submersible and water- proof. The connectors are H4-MC4 indus- try standard. Diodes (often outside the sail) are used to protect each side from polarity inversion, with the circuit breaker at the tack used for extra protection. Power Sails generate DC power, while the thin film solar panels can be wired in series or in parallel, depending on the existing system and the output and voltage required. Thanks to internet chatter after the Route du Rhum, it took only a few days for Finnish electric engine manufacturer Oceanvolt and the Arcona boatyard in Sweden to contact our Swedish office with a view to working together on the zero- emission Arcona 380Z programme, the world’s first zero-emissions production sailboat. The first 380Z was launched last May in Helsinki, the result of an exciting collaboration between diverse companies in Sweden (Arcona and UK Sailmakers), Finland (Oceanvolt), Netherlands (SuperB lithium batteries and Victron regulators) and France (UK Sailmakers and Solar Cloth System, manufacturing the 1kW Power Sail).
The Arcona 380Z and Power Sails project involved manufacturing a combi- nation of internally integrated and ex - ternal removable solar films. Normally the membrane-integrated solar films are set above the first reef, although for the Route du Rhum the panels were placed between the two top full-length battens to ensure better longevity and also because the head of the main on an Open 50 normally pro- trudes out of the cover while in port. It’s still preferable to install solar panels on a full-batten mainsail for durability reasons, but we are slowly moving into outfitting standard short batten mainsails as well. Another important project came up last summer: a prototype boom furling Power Sail main for the Minibee 6.50, a dayboat
manufactured by Building A Future Foun- dation, promoting the marine industry in Sri Lanka. In this case, the possibility of furling and unfurling a solar sail for an extended period of usable life could open the door to other major applications: replacing the UV cover by solar films on furling genoas, ‘self-powered’ sun awnings and shades for shops, building-integrated photovoltaic (BIPV) applications and even self-powering solar tunnel greenhouses. Power Sails’ most recent deployment was last autumn at the Newport and Annapolis boat shows, delivering to J/Boats a 400W solar mainsail for the new J/88e (electric), which combined Power Sails with an Oceanvolt SD6 electric engine, Valence Lithium batteries and Victron regulator to create the world’s first solar/hydro-powered J/Boat.
For J/Boats the aim was to achieve silent operation under power, delivering an emission-free low-maintenance motoring alternative. (To further the green theme, both Arcona and J/Boats have also been experimenting with alternatives to toxic underwater paints, J/Boats opting for ZO Antifouling and Arcona choosing the Sonic Shield system from CMS Marine, using pulses at ultrasonic frequencies.) Several French and American boat- yards, including multihull manufacturers, have since shown interest in our clean sail- ing approach. The average speed of multi- hulls and the need for two engines make them a good candidate for the hydro gen- eration or ‘creating energy while sailing’ function of modern Z-drive electric engines, while the large surface area of a typical cruising cat’s fully battened main- sail plus bimini top also offer excellent opportunities for a Power Sail installation. Overnight racing boats (Fastnet, Middle Sea Race, Newport-Bermuda, Sydney- Hobart, and so on) could similarly employ a narrow strip of solar film above the first reef, not large enough to add significant weight to the sail, but big enough to make it unnecessary to crank up the engine early in the morning to recharge batteries to keep the electronics running. Power Sails are now developing a targeted product for this application.
There is a growing conviction among all sailors about the need for clean boats, clean regattas, clean seas and better practices to help conserve and protect the oceans. The marine industry is starting to mobilise for a systemic change for the health of the marine environment. In this quest the sun may well be our best ally.
SEAHORSE 51
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