If I was to completely cover the unused space on my 38'
boat, I would have about 12 square metres. Using flexible
panels and in sunlight directly overhead, I might generate 8 kw at the maximum. If I then take into account sail bag shading, sun angle, rocking and rolling etc, I might generate 5 kw I might get that for 5 hours on average, but that's 8 hours in summer and 3 hours in
winter. With or without
storage, that will not drive your
boat very fast. I get a maximum of 8 knots out of my 36kw
diesel. your
solar panels will not provide sufficient
power. You will not be able to
motor on cloudy days, before 10am and after 6pm. There have been recent warnings about frequent walking over flexible
panels as the eventually suffer damage, You might easily damage the panel with chains and shackles even a flicking line. I read somewhere that they really only
work well when there's an air gap behind them to allow air circulate and cool.
Your
storage batteries will not help you much. a 200 amphour lead acid stores 1kw of usable energy. If it was a lithium
battery, it would store 2 kw. If you had 36 lead acid batteries on board, you would be able to
motor at 8 knots for one hour. It would take a whole day to recharge the batteries assuming you have a 5kw charge controller. Those batteries would cost you about $10,000 and might be good 3-5 years. Lithium last longer but cost much more. The lead acid batteries add more than a tonne to your boat. Lithium maybe 500kg. Remember, this is for one hour of motoring, maybe 2 if you take it easy
It's much the same with generators. On a sailboat there is little energy advantage having diesel electric over straight diesel. You consume the same amount of diesel to do the same
work. There are inefficiencies with any energy conversion and storage that increases the energy demand. Remember too that a kw is a kw whether it's produced by a diesel or an
electric motor.
Don't cite cars like the Prius; they are petrol cars that use an
electric motor to start from rest but not much more. There are plenty of cars around that get the
fuel consumption of a Prius. Remember too when comparing cars and
boats that the energy transfer on a boat is by
water propulsion and that is very inefficient. I use 4 litres of diesel to travel 14 km when the same size motor will propel a car 80+km on the same amount of
fuel.