[C320-list] Re Solar Panels

[Scott Thompson]

I went through this earlier this year as part of a canvas replacement 
project where we purchased a new bimini, dodger, etc. I purchased three 
Solbian SP52Q panels (see 
https://www.solbian.eu/en/sp-series/24-sp-52-q.html). These were 
installed on the aft part of the bimini, with one panel on each of the 
three sections divided by two zippered cut-out slots for the backstays. 
The bimini was built by Yacht Canvas (formerly Christopher Ford Yacht 
Canvas) of Annapolis, and they added zipper attachments for the panels 
as well as adding various openings and channels to hide the wiring. They 
also attached the panels to some kind of air-core board that allows 
limited air flow below the panel to help keep them cool. Two relatively 
heavy-duty weather and UV protected cables spiral down the starboard 
backstay and then go into the clamshell vent on the transom before 
joining internal wiring below the starboard helm seat. Wiring from their 
forward to the battery compartment is via standard duplex boat DC wiring 
cable. All connections used MC4 connectors that came with the panels. I 
had to purchase a special crimping tool to install these, but they 
produce weather tight connections.

After some research I decided to wire the three panels in series. This 
combines them into a single 28 volt array adding up to 156 watts peak 
power. I wired them to a Victron MPPT 75/15 solar controller that I had 
installed earlier anticipating this upgrade. I also installed a Victron 
solar controller monitor so that I can see what the MPPT is doing. (The 
newer controllers have bluetooth built in so that you can use your phone 
to monitor, but that wasn't available when I bought mine.) I already had 
a Victron battery monitor and the two monitors were installed next to 
the starboard-side battery switch.

Note that the SP52Q panels have an output voltage of 9.1 volts so I'm 
not sure they would be appropriate for use in parallel with a 12 volt 
system -- the controller would need to step up the voltage rather than 
step it down in that scenario.

I was very pleased to see during our first cruise with the new setup 
that we often were getting 120 watts out of the array. This was more 
than enough to keep the batteries charged while sailing on a sunny day, 
even using the autopilot for steering, running the fridge, and using 
instruments including a chartplotter. We also spent three nights at 
anchor in one location and the system was able to restore the batteries 
to full charge each day. We are pretty conservative about power use at 
anchor. The biggest draws are the fridge and the stereo. LED lights draw 
next to nothing. We do not have an inverter, and actually got rid of our 
microwave.

Wiring in series means you have a higher voltage but lower current in 
the wiring back to the controller. This means that the MPPT controller 
can more efficiently use the power when the panel output is below 
optimum, and it also means you can get away with somewhat lesser wiring 
sizes and still avoid significant voltage drop on the relatively long 
wiring run back to the batteries. With series wiring the current back to 
the MPPT controller is limited to the 6 amp output of any one panel. 
However the MPPT controller steps down the voltage so that many more 
amps are available to the batteries when the sun is shining well. The 
drawback of series wiring is that if one of the panels is shaded all the 
way across then the entire array shuts down. But since Surprise lives on 
a mooring, and since we usually anchor out while cruising, the only time 
that's going to be a problem is if the mast casts a shadow across the 
back of the boat. Mostly it's not a problem for us. Some websites 
recommend parallel wiring and a separate controller for each panel. That 
would mean three times the wiring.

Scott Thompson

Surprise (#653, 1999)



On 6/11/2019 12:11 PM, Jeff Hare wrote:
> I'll, of course, defer to others who have already installed panels.
>
> But something quite important to consider and maybe not at all obvious, is how the actual panel itself was designed to be used.  Specifically, you could take 4 differently designed 100w panels and see vastly different outputs from them depending on how the cells are wired and whether there are electronics built in to handle the effect of partial shading.
>
> For purposes of illustration: you might have a panel that is designed for use in full sun.  It'll put out rated watts with optimal sun but shade 1/4 of the panel, or even a couple of cells and you might find that panel produces almost nothing.  Shade a different 1/4 of the panel and you might get half power out.  It's like having a bunch of battery cells wired in series or series/parallel. If you have a dead cell (shaded), it affect the rest of the cells in that string.  So, really good solar panels can do things to mitigate any cells that get shaded and still use the others, while less sophisticated panels might not be able to do that at all or are better for applications where it is never partially shaded.
>
> So, consider the design of the panel and how it deals with patches of shadow before you buy the panel.  https://www.wholesalesolar.com/blog/effect-shade-solar-panels/
>
> I'm not an expert but did quite a bit of research at one point on solar.
>
> Cheers!
> -Jeff Hare
>
> -----Original Message-----
> From: C320-list <c320-list-bounces at lists.catalina320.com> On Behalf Of Tom Grass
> Sent: Monday, June 10, 2019 9:24 PM
> To: C320-List at catalina320.com
> Subject: [C320-list] Re Solar Panels
>
> Need advice on solar panels and regulators.  We are thinking of installing some panels on Bucket List.  How many watts did you install?  Did the install integrate well with your inverter?  Where did you mount the
> panels?   Was the wiring a problem?  Any advise is appreciated.  Tom Grass
>   SV Bucket List. 2008 Catalina 320 MK II. #1135.
>
> On Sun, Jun 9, 2019, 11:51 AM Jack Brennan <jackbrennan at bellsouth.net>
> wrote:
>
>> Well, I’m finally done with replacing the cabin sole with Lonseal teak
>> and holly laminate. It was a success, but I have to say it was the
>> most meticulous, unforgiving project I’ve taken on in three major
>> refits of sailboats.
>>
>> Some notes for anyone contemplating this project:
>>
>> • If I had to do it over again, I would choose the solid teak pattern.
>> Lining up the holly stripes is extremely difficult and time consuming.
>> Remember, there are five hatch covers for the bilge and six separate
>> floor sections in the cabin … • Thickened West System epoxy worked
>> great. I mixed four separate batches to keep it from hardening. First
>> the V berth floor, then the forward cabin area, followed by the large
>> port and starboard sections in the rest of the cabin.
>> • An expensive, really sharp utility knife is your friend. With a
>> little practice, you can cut extremely accurate lines in the laminate
>> if you take your time.
>> • Even if you plan on cutting a new underlayment for the laminate, be
>> careful to protect the old stuff when you remove it. Making your own
>> pattern without them would be very time consuming.
>> • On my 320, small screws through the laminate hold the floor
>> underlayment to the subfloor. I chose to continue doing this, and it
>> made it much easier to cut and glue down the laminate. I would take up
>> a couple of screws, lay down the glue and rescrew the laminate down to the subfloor.
>> • Lonseal comes in six-foot-wide sections. Ten feet, costing about
>> $400, is plenty.
>> • Lastly, if you have a fat bank account, this really is a project
>> left to a floor professional. I did it myself to stretch my boat
>> budget and because I’m retired with plenty of time. My guess is that
>> it would cost 3K or so, based on $800 in material and $2,200 in labor.
>>
>> Jack Brennan
>> Sonas, 1998 Catalina 320, no. 528
>> Tierra Verde, Fl. Dolphin Cruising Club of Tampa Bay.
>>
>>
>> Sent from Mail for Windows 10
>>
>>
-- 
Scott Thompson
Surprise, #653