Ill post in this thread since Im messing with my solar panels today. Dan, you might take a look at your Bimini for shading as my Bimini (folded up) was creating a shadow on just one end of the panel that was really killing the solar output.
My story.. my 26S is in a slip in Lake Havasu Az and the boat is oriented W/E. The boat will be in this slip all winter (a good thing..). Today is Nov 26 and the sun is almost to its lowest arc in the Southern sky and Ive been noticing that the 10 watt panel is doing little to contribute to charging the batteries. I had two problems. One is that my Bimini was right next to the panel and it would create a shadow on just the bottom row of cells (covered by the rope in the picture below). Panels are always some combo of serial/parallel cell connections and apparently the shading I had happening was really bad as I was getting almost no output from the panels. In the picture below, I put a rope across this same row, it cut the panel current to about 1/3 (YIKES)..
So one mod I just did this morning was to move the panel back and raise it a little - plus I put added some angle because of the low winter sun. The angle matches the slip Im in.. if I put the boat in backwards it would just kill the output. At about 11 AM this morning, I was getting about .4 amps out of the panel. This is how the boat will be set up for the winter, the charging all gets done when the boat is in the slip.
I also have a removable 40 watt panel that I can change both the elevation and azimuth on. I don't like this on the boat when sailing but I left it on the boat in the slip to top the batteries back up (they are only down about 6% but.. I still want them topped off.
With the 40 watt panel, I measured the current with the panel pointed straight up (11 AM Nov 26). I was getting 1.1 to 1.2 amps out of the panel.
I then angled the panel to match the low November sun and pointed it close to directly South. I was then getting 2.5 amps. This time of year, I nearly doubled the output by being able to change the panel angle - and of course this only works because the boat is a slip but that is also where the majority of the charging will take place.
I left the 40 watt panel on the boat to get the batteries topped back up. Next time I go sailing I will remove the 40 watt panel and stick it up in the Vberth area and just use the 10 watt panel. What I expect is that every few weeks I will have to put the 40 watt panel on the boat for a few days. When the sun gets higher in the sky, I probably wont even need the 40 watt panel based on what I have seen so far.
FYI, the 40 watt panel is my RV mode trip panel. If I spend a week for example at Lake Powell, I will have this panel on the boat. When Im marina lake sailing, its nice to have only that 10 watt panel on the boat.
