[C320-list] Solar panels on bimini

[John morrison]

I have a 180W panel  mounted on dinghy davits connected to a Blue Sky,(2512iX) MMPT( which is the standard these days)  controller. I have had it for 5 years now and it keeps the batteries fully topped up when we are on the hook, unless we get a few cloudy days and then the batteries will start to draw down. The largest consumer on the boat is the fridge.
Have you done an assessment of your daily amp/hr requirements? This is the first thing to be done to determine the optimum size of panels to mount. 3 panels seems a lot to me, unless you have very thirsty consumers hooked up to an inverter, as an example.
> On Mar 5, 2019, at 3:24 PM, Scott Thompson <surprise at thompson87.com> wrote:
> 
> 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)
>