Solar instalation: fuse & cable sizing

[rgleason]

Thank you for the explanations, all very clear and helpful.

I am considering two panels on the doger top, probably 60 to 80 watts each, one on side of the boom, possibly wired to the same controler. Then the next improvement would be two 130watts each on either side of the backstay behind the boom. I am guessing that each one would need a controller.
These would be the thin, light type of panel. SP-130 etc.
To reduce the effect of shading on the dodger, how would the two panels be wired?

[Dsanduril]

Originally Posted by rgleason

... To reduce the effect of shading on the dodger, how would the two panels be wired?

The general rule of thumb, panels should only ever be wired in series when you can guarantee that sun exposure will be identical on all panels in the string. If you wire in series and one panel had reduced output because of shading the current that it puts out will be the current of the entire string, thus reducing total power output.

Since almost all boat installations involve variable shading parallel is generally better than series. With the price of small MPPT controllers coming down even better is a single controller per panel, but you'll have to weigh the cost/benefit of that if putting in small panels.

[Nicholson58]

Originally Posted by SVRapture40

Size your fuse to the total output that you expect from the panel array. Then google wire size chart and download. It will tell you everything you need to know about wire size for any application (volts / amps / length). Really handy to have around!! I'll bet there is even an app these days to calculate wire size.



Sorry - teaching you to fish here instead of giving you a fish. Hope you appreciate it.

Always go up In wire size. You have too much invested in this system to expend power heating wires and air.

Each panel should be individually fused so you can disconnect for maintenance. I use two pole breakers.

[rgleason]

Dsanduril
Thanks, It looks like a controller for each dodger pv panel and possibly parallel the 2 two aft panels.