Solar panel technology has improved tremendously in the past few years. The panels are highly efficient, flexible, walkable and comes with very low weight. They can be attached to the deck or canvas with fasteners such as Tenax/Loxx, using velcro or glue. Some panels are suitable for boom/mast assembly as well. The latest technology allows also putting panels onto sails.
Oceanvolt uses solar panels from Sunbeam. The panels have proven to be reliable and efficient with good value for money.
The panels can charge either 12/24 VDC house battery or the 48 VDC propulsion battery bank. Charging the house battery bank is no different than in normal installation: a charge controller must be added compatible with the panel power. Charging a 48VDC lithium ion propulsion battery bank is however a little more challenging.
Lithium Ion batteries require careful balancing to remain fully operational. The balancing is a slow process and thus can be completed only with shore power charger or with solar power: a generator or regeneration under sails can never reach the 100% level as the process is designed to cut off the charge at 80-90%. In applications where shore power is not available some solar power is a requirement – Oceanvolt recommends minimum 200 W of solar panels in this case.
Using solar panels with Oceanvolt propulsion system requires either Victron MPPT series charge controller or Genasun Li-Ion Boost controller. The former is used where the amount of panel voltage is 60-150 VDC/70 amps, the latter if the panel voltage is less than 60 VDC (max 8 amp). The advantage of the Victron MPPT is that it does not require an external balancing relay (the Genasun requires this) & it is fully compatible with the Victron GX which allows remote monitoring of the solar yield.
Panels on the same side of the sun should be connected into the same group if connected in series. Otherwise shading will have significant effect on the power. However, two panels on the opposite sides of the boat can be connected in parallel: one is likely to be on the sun when the other is not.
There is no upper limit for the amount of panels. The number of MPPTs depend on the amount of panels. Oceanvolt has done boats with up to 5 kW (50x 100 W) panels.
SOLAR MOTORING
It is possible to do solar motoring with the Oceanvolt system. The system shows the current yield from the panels and the motor speed can easily be adjusted to match the solar power to get independency. Typically 1 kW of solar gets about 3 knots for a boat suitable for Oceanvolt motors.