Manlio:
I cruised for a few years with 200 watts of solar panels on board. These
supplied 1/3 to 1/2 of my power requirements. Here are some observations:
1. Solar panels cost about $5 per watt. Big ones less, small ones more,
flexible panels more.
2. There are 17 volt (open circuit voltage) panels that can be used without
a controller (if you are careful) and there are higher voltage panels that
absolutely require a controller (to charge a 12 V battery).
3. MPP (maximum power point) controllers are about double the cost of a
standard controller, but produce 10% or so more power. I wouldn't bother
unless I had more than 100 watts of panels.
4. A good rule of thumb is that a 100 watt panel will produce 33 amp hours
of power on a full sun day. More at lower lattitudes and less at higher,
more in the summer, less in the winter.
5. Mounting is a real problem on a boat. I mounted one large rigid panel on
the dinghy davits and sewed three flexible panels to the bimini. The
flexible panels were more tolerant of partial shading due to their internal
diodes.
6. Wire your panels with large gauge wire. I used 10 gauge. My panels put
out about 13 amps at full output and I wanted to minimize votage drop.
Protect the wiring with a breaker or fuse. You can use a cigarette lighter
outlet to charge your boat's batteries. Electrons can flow both ways and the
lighter outlet is usually circuit breaker protected. This scheme won't let
you use a controller but is great for smaller panels.
There are lots of suppliers. Google (or Froogle) solar panels and you will
get lots of hits. I like Backwoods Solar Electric Systems. Run by real off
gridders.
The foregoing should get you started. Go to the suppliers sites and read
what they have to say.
David
