Let me say we have an interesting crew on board this thread. Accepting and ignoring some of the more ridiculous responses, LoL, is pretty normal for such a motley group, e.g. when I put my sailboat up in space, Iíll definitely put in a thermal loop with a liquid capable of dealing with both the hot and cold sides of my ship. I suppose talking about how R/V coolant
wonít cut itÖ but until that day, Iíll stick to more practical facts and info. So mikk60, yea, I agree, but moving onÖ
I agree with Seabeau about mounting panels on dual wall polycarbonate. Yesterday I visited a Lowes hardware
store to look at the 6mm and 8mm panels they had in stock. RV folks have been doing this for a number of years with great success. Particularly when the RV is in motion air flows under the panel as well as above with forced convection. However, on a sailboat, particularly at anchor
airflow needs to be a bit more aggressive. Convection isnít going to happen much with either the 6 or 8mm, so I opted for 10mm which is sold
at ePlastics.com and ePlastusa.com, among others. I talked with the staff at ePlastics about walking on the poly panel, they indicated that the 10mm, if fully supported underneath, like laying on a near flat deck
, would work
without crushing. They suggested no jumping. The 10mm has some reasonable air passage
way which should allow better cooling of the backside of the panel. I will update the forum in a week or two when the stuff has arrived and Iíve tried it.
So, who can tell me which adhesive
has the most thermal conductivity? LoL (back to the space discussion). Obviously ďgluingĒ the solar
panel to the polycarbonate actually will have some impact on that conduction of heat which then will be aided by the convection of air through the honeycomb. Thin epoxy
with full surface contact might tear the backing material with heat/cool cycle expansion and contraction. Silicon based caulk give a fair amount of flex for the latter but sucks in regards to adherence. Any suggestions on this part? Seabeau, what did you use on those semi-flex? In my case I am using fully flexible panels, so there is no thick backing nor walk-on coating on the surface.
These panels are sandwiched: ETFE film : EVA film : HE Solar Cells : EVA film : TPT Backsheet . I am intending to give up some of their flex to get them cooler. Frankly the flex in my mind is only there to be able to get them onto a non-flat surface, as flexing them will obviously destroy them in the long run.
I also agree with the comments that converting the honeycomb channels to hold seawater, or freshwater for those cold shower
mates, is a bit of a hassle, adds weight, complexity and well, a whole bunch of hassle for a few more watts. While I am sure the net benefit is positive (wattage of pump
vs. wattage returned) it just seems to much maintenance
and annoyance. I appreciate the tube snake backing that CustomMarineProducts makes, but what a hassle it would be hosing it to the engine
room etc. and worse, yes, once the water was hot in the loop, there is no more cooling for the panel. If you pick 10mm dual wall polycarbonate, pick the ones with the hollow center. There are other varieties which put cross-members inside the 10mm channel which will make them to small for convection to occur freely.
However, that said, for you cold shower
folks, you can convert these dual wall polycarbonate panels for water with a Dremel tool, wire stripper, or a needle nose wire cutter
, and two strips of polycarbonate and some poly-glue. At the ends of each of the panels where the channels open, cut back the last 10-15mm on every other channel and alternate the other end. Put one strip over the end of the panel (10mm wide) over the surface are where you cut, - they make a 10mm strip for adjoining panels together which could be used for the end strips. see attached pic. The panel then becomes a single
snake channel flow for circulating water, if that is what is desired. Attaching nipples at each end or other hot water hose attachments with JB Weld poly glue (an epoxy
actually) and youíve got your cooling coil. That was the original concept
for cooling the panels with seawater. It just seems that unless the panels are fixed and all that hosing and connections are solid, it is a nightmare waiting to happen, winter
needs winterization and draining...
Iíll post again once Iíve tried the air-cooled version of this all.