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Old 30-06-2022, 10:33   #106
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Re: Water cooled solar panels.

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Originally Posted by Mauruuru View Post
There are Gigawatts worth of solar panels installed on black roofs and in deserts that are not cooled by anything but ambient air flow across and around the panels themselves and they have a service life of 40 years......why would you imagine you need to cool them with water?
The OP asked a very good question. Since PV output declines with increasing temps (starting from reasonable ambient temps - I don't know if it is true down to ~0K), s/he asked if one cooled the panels, would the power gained by lowering the temp of the panel be more than the energy used for the cooling mechanism? It is a great question!
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Old 30-06-2022, 11:56   #107
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Re: Water cooled solar panels.

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Originally Posted by lestersails View Post
The OP asked a very good question. Since PV output declines with increasing temps (starting from reasonable ambient temps - I don't know if it is true down to ~0K), s/he asked if one cooled the panels, would the power gained by lowering the temp of the panel be more than the energy used for the cooling mechanism? It is a great question!


Pondered on it myself at times and decided that the increase was not worth the trouble. Efficiency is an important consideration on a boat where the real estate available for panels is limited.
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Old 01-07-2022, 13:09   #108
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Re: Water cooled solar panels.

I don't know if anyone brought this up yet, but when we were outfitting our boat for our Bahamas trip, we were looking at solar panels. Custom marine products in Michigan already has a kit for this. They advertise it as a way to get hot water for your boat. Water circulates from the solar panels to your hot water tank and back to the panels over and over when you open the system. 3 years ago it was advertised as an efficient way to get hot water without expending energy, not as a way to cool the panels. I can't say if they updated their advertising to include this aspect.
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Old 01-07-2022, 16:03   #109
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Re: Water cooled solar panels.

I remember that very package from Michigan. Great stuff. The panels are from Flint. Very nice stuff
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Old 01-07-2022, 17:03   #110
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Re: Water cooled solar panels.

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Originally Posted by Allied39 View Post
Yes yes, absolutely...

Sorry my bad. Continue, please. Much to ponder.

Allied 39's bio (and I quote):
------------------------------
"Interests
not dealing with low talent idiots on forums.

Biography
I have a low tolerance for stupid. Fortunately I am in a position to just walk away.
Bye."
-------------------------------
This is too funny!
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Old 01-07-2022, 17:39   #111
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Re: Water cooled solar panels.

Nice to know. Iíve learned over the years there are idiots amongst us everywhere. I suddenly realized some were my best friends and was relieved.

When youíre dead you donít know youíre dead, itís hard on other people.
Itís the same when youíre stupid.

So forgive us and show us the light.
Or medicate. Iím combining rum with Indica no wind anchors quiet.
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Old 02-07-2022, 02:45   #112
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Re: Water cooled solar panels.

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Originally Posted by blueskymessenge View Post
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.
The cheap Nature Power panels come with grommet holes that are approx. 3/4" in dia, all around the perimeter. At each grommet hole location I marked, then bored enlarged holes in my cabin top, and filled each with epoxy per Rod Collin's excellent waterproof fastenings instructions. Afterwards, I marked the locations of the center of the holes on the epoxy, then bored pilot holes, and simply used 1-1/4"X #10 316 SS screws with 1-1/2" dia fender washers and lock washers to go through both the panels and the 8mm thick glazing, Here in coastal GA our summer temperatures regularly rise above 100f. Incidentally,
I walk on my panels all the time with no ill effects.
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Old 02-07-2022, 02:59   #113
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Re: Water cooled solar panels.

Seabeau. Lexel would be a good product for that.
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Old 08-07-2022, 18:10   #114
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Re: Water cooled solar panels.

What about a water scoop pickup that does not have a pump, think like a small funnel or scoop, underway the forward movement of the boat will force water into it and send it to the copper cooling coils then it drains back in the ocean.

Now what about a syphon type system so the water that gets pumped up will get pulled down by gravity, it will use a foot pump or squeeze bulb like small outboard gas cans have to prime it or get it flowing.. Even if the syphon system was neutral from the water weight you could lower the amps for the pump by a LOT.
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Old 08-07-2022, 21:04   #115
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Re: Water cooled solar panels.

Then you run into all the problems of drag coefficients etc, and extend the argument to beyond the 'will the fan use more than it produces' question of the OP.

BUT.....if the 'scoop' was designed according to "ram air" principles (but for water), so had a tall but narrow opening, offering the least resistance, and then a small diameter hose/pipe leading to the top 'radiator tank' allowing water to then flow according to gravity under the panels and exhaust overboard again........????

Hmmmmm......
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Old 08-07-2022, 21:13   #116
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Re: Water cooled solar panels.

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Originally Posted by Buzzman View Post
Then you run into all the problems of drag coefficients etc, and extend the argument to beyond the 'will the fan use more than it produces' question of the OP.

BUT.....if the 'scoop' was designed according to "ram air" principles (but for water), so had a tall but narrow opening, offering the least resistance, and then a small diameter hose/pipe leading to the top 'radiator tank' allowing water to then flow according to gravity under the panels and exhaust overboard again........????

Hmmmmm......
I'd think it could be 1 inch or even 3/4 of an inch or so, I doubt the drag would even be measurable.
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Old 17-07-2022, 19:16   #117
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Re: Water cooled solar panels.

Then the drain exit in the stream could be a shape that "pulls" the water out of the system, enhancing the ram entry effect.

The drag would be slight, compared to the power of the sails.
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Old 17-07-2022, 20:56   #118
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Re: Water cooled solar panels.

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I'd think it could be 1 inch or even 3/4 of an inch or so, I doubt the drag would even be measurable.

Perhaps, for keel boats, the 'ram scoop' could be let into the leading edge of the keel, and sea water piped via a 3/4" tube vertically to the cabin top, under the panels and thence overboard.

Obviously there is a danger of marine growth with this idea, which is why I initially suggested a 'deployable' type of 'ram water scoop', something much more readily cleanable, and only requiring deployment in daylight hours, thus reducing the likelihood of marine growths attaching themselves.


Or, having attached themselves, finding themselves out of the water overnight would probably lead them to detach themselves, or die off such that they could be easily cleaned/scoured/scraped off before redeployment the next day.

Would love someone to actually experiment with this idea, as I'm currently landbound...?

Anyone willing..??
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Old 17-07-2022, 22:52   #119
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Re: Water cooled solar panels.

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Originally Posted by Buzzman View Post
Perhaps, for keel boats, the 'ram scoop' could be let into the leading edge of the keel, and sea water piped via a 3/4" tube vertically to the cabin top, under the panels and thence overboard.

Obviously there is a danger of marine growth with this idea, which is why I initially suggested a 'deployable' type of 'ram water scoop', something much more readily cleanable, and only requiring deployment in daylight hours, thus reducing the likelihood of marine growths attaching themselves.


Or, having attached themselves, finding themselves out of the water overnight would probably lead them to detach themselves, or die off such that they could be easily cleaned/scoured/scraped off before redeployment the next day.

Would love someone to actually experiment with this idea, as I'm currently landbound...?

Anyone willing..??
Early on I suggested the use of alcohol to implement a heat pipe to remove the heat from the panel. How to do it?

Well first one needs to bring the liquid alcohol into intimate contact with the underside of the panel. Shouldn't be that big a problem since no pressure is involved.

Then after the liquid alcohol vaporizes one needs to pipe the vapour down to the vapor/seawater heat exchanger. Bit of plastic hose would probably do it.

Then, after the heat is taken from the vapour and it turns back into liquid you need to pump the liquid back up to the panel. Magnetic coupled centrifugal, or peristaltic, pump and a bit more plastic hose should do it.

If you don't charge for your time input about $100 or so should do it.
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Old 20-07-2022, 14:29   #120
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Re: Water cooled solar panels.

Alcohol boils at a temperature of 78 degrees Celsius.
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