[C320-list] Solar panels on bimini

[Scott Thompson]

I have a new bimini on order (now under construction) and want to have 
solar panels installed on top of it. I'm getting ready to order panels.

In anticipation of this, a few years back I installed a Victron MPPT 15 
solar controller and ran wiring to the stern. I've had a lightweight but 
not flexible panel tied to the top of my old bimini for the last few 
years and it has done a fine job of keeping the batteries topped off 
when we are not on board. (Surprise lives on a mooring and is rarely 
connected to shore power.) Now I'm looking to increase the total amount 
of solar power collected, as well as making the installation more 
permanent and less ad hoc. This leads to a few questions:

Have any other 320 owners done this? If so, what is documented about the 
experience? Any tips? Dos and donts? Brands or designs that work well or 
do not?

The bimini has three sections aft of the middle bow, divided by two 
zippered slots so that it can go around the split backstay. I'd like to 
install three panels. The middle section is much larger than the other 
two, and therefore has room for a larger and higher output panel. I had 
been planning to add three panels -- one in each of those sections of 
the bimini -- wired in series for a maximum total voltage of 36 volts 
approximately) that will be stepped down to normal charging voltages by 
the MPPT controller. This is supposedly the advantage of MPPT 
controllers over older designs -- that you can harvest more energy by 
converting excess voltage to amps through the step down process.

However, I've been warned that I shouldn't put different sized panels in 
series -- that the power will be limited by the smallest panel if I do 
-- and that it's not a good idea to wire panels in series in any case 
because a shadow on one panel reduces the output of the other two as 
well. These same sources suggest that a better way to do it is to wire a 
separate charging circuit for each panel, meaning three MPPT controllers 
and three cables running up the backstay to the bimini. I'd rather keep 
it simpler. Does anyone have any thoughts about the best approach here? 
I'm not too worried about shadows on the panels given that the boat is 
usually on a mooring and so the only shadow to worry about is from the 
mast. So perhaps my best approach is to keep the three panels wired in 
series but size them equally, which means giving up some area on the 
middle one.

Any related thoughts or advice will be welcome. Thanks.

-- 
Scott Thompson
Surprise, #653 (1999)