Which to use: One panel or 2 when shaded

[jbinbi]

I put up a post about whether to hook up 2 sets of panels in series or parallel, but this one is about if shaded whether or not I should put on a single 100W panel that goes across the top of the dodger or put 2 50W , one on each side of the dodger.

See pic, the boom will be over the top of the dodger, so I am assuming part will be shaded. The boat on the mooring will face south, so the boom will cast a shadow on each side of the dodger throughout the day. Sailing is a different story of course.

My question is, if I have a single 100, or I could even go to 175W panel , that I put across the dodger, or put 2 50s (best I can fit with 2) , one on each side. I am not sure when the boom casts its shadow how effective a single 100W/175W panel becomes. I will certainly get most of 50W from the unshaded panel plus something from the shaded panel.

The bimini will take a single 175 across the back of it. That seems the best I can do, there are holes in back section for the backstays, and windows in the front section to look up to see the mainsail.

[smac999]

the 50w in total sun may put out more then a 100 or 175 with the boom across it. but hard to know for sure unless you test both... generally a small shaded part will take out most of the power. its' definatlly not 1:1 of shaded area to power loss

if you get 2 50's you'd also need 2 controllers. having one shaded and one unshaded panel on same controller you just end up back where you started of losing a lot with the shade.

[LifesBetterWhenYoureBeating]

On a mooring, If you leave the boom above the dodger, even with two panels it is likely to cast a shadow on one or the other during parts of the day. If you ease the main sheet and lock the boom to either side with a preventer you don't have to worry about that

[boatpoker]

I have two 315 Watt panels on my pilothouse (avatar) each independent with their own controller. My mast and riding sail (which is up all the time) are the shadow issue. It is not uncommon to see one panel put out 2 or 3 amps while the other puts out 30 amps or more.

If it was one panel I might get a total of 4 or 5 amps instead of a total of 33amps.

[Uncle Bob]

^^^^^^^^^^
This, multiple panels is a no brainer. Do it and move on.

[Rustic Charm]

I’m new to this stuff as well. I’m intending on putting two 200w panels on my pilot house roof. Which is under the boom. My intention was to have a controller for each…. ?

[boatpoker]

Originally Posted by Rustic Charm

I’m new to this stuff as well. I’m intending on putting two 200w panels on my pilot house roof. Which is under the boom. My intention was to have a controller for each…. ?

Thats the way to do it.