I've been experimenting with solar panels since 2012. (When you think about it, everything on the boat is an experiment waiting for replacement with something better.)
After about eight years on deck:
Obsolete SunForce: not good. No longer sold.
Ganz semi-rigid: really good.
SunWize semi-rigid: weak.
DMSolar 158W rigid panels: good.
GoPower semi-rigid. We'll see.
This experiment started with a free SunForce 15W panel. It was in a catalog of service awards for patiently working at the same company for five more years. It had a Coleman brand on it, and came with a little 7A controller. (I'd post a picture, but, it's in the bottom of the dumpster.) It was glass and plastic.
Here it is laying on the foredeck.
I bought a matching panel, but the glass cracked one cold December day when I moved it. The other one never cracked. But 8 years on deck killed it somehow. SunForce doesn't make them anymore; the newer versions seem to have an aluminum frame.
Actually, I'm not really sure when the panel died. I do know that when I finally replaced it this week, it was dead. I did not carefully monitor it through it its life.
Two 15W panels is really about 2A of charging power. (amps = watts / volts; batteries charge at about 14-15V.) So this wasn't a bold step up into solar power. It was an initial experiment.
Beyond The Free
Routing the wire(s) down to the engine room was emphatically not fun. There's no great route from deck to where we have batteries on the port side of the boat. I poked a hole in the lazarette.
I added two tiny Ganz panels on the aft lazarette covers.
These are something like 6W each. 12W is just under 1A. Trickle charge on a bright, sunny day.
There's room for two more.
I didn't fill the tops of the aft lazarettes with a total of four panels because I wanted to know how durable they are.
These little guys are tough.
You can see that I put in a big sticks-up-in-the-air wire gland. Which — while watertight — might be a potential problem. So far the last 8 years have been problem-free. No stubbing of the toes. Nothing.
They're still ooching out a little dribble of power.
This lead me to put two proper 185W panels on the top of the dodger.
These are household units. Big. Rigid. Heavy.
Larger than the dodger by several inches, they require some care to work around. But. They're capable of 10A each panel. The boom is right there, so one is always partially shaded. But. They produce and have been producing without a problem for 8 years. I chose this specific model because it was on sale. No other reason.
Back to the foredeck. Just in front of the dodger. Under the main boom. Near the wooden grabrails. When the 15W SunForce panel broke, I replaced it with two 24W SunWize semi-flexible panels. In parallel, these can provide a bit over 3A.
These are not as rugged the Ganz. Indeed, they've more-or-less fallen apart over 8 years. There's no glass, so they don't crack.
You can see the delimitation around the edges — little bubbles where the top layer has pulled away from the panel. The bottom is particular bad — over an inch deep.
These still actually work. They still generate some current.
But they suffer from a huge problem: awkward non-standard wiring. There's no easy provision for MC4 connectors. There's a tiny two-wire cord that you have to split and connect something to. Since the wire is 16 or 18 gauge, a big 10 gauge MC4 connector is out.
I tried to connect directly to MC4, by splicing in a short chunk of 10 gauge. My splices didn't weather well. Not enough heat shrink, I guess.
I also used some IP68 connectors to try and bridge between the panel's writing and wire that fits a more standard MC4 connector. (Find these connectors at Superbright LEDs)
I'm not delighted with the wiring complications required to make these panels work with other, more standards-compliant panels.
Also, of course, I'm not delighted with their delamination.
Also, I found one of these.
This is an MC4 where the case cracked.
I think this means I should inspect the wiring more often than once every 8 years.
The state of the art in solar panels is advancing rapidly. Old panels are less efficient, and less well made. I hate to clutter land-fills with old panels, but they're not working well and need to be chopped up and recycled.