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Old 26-11-2022, 07:52   #1
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Ultimate solar panels

I'm sorry if this was discussed over and over but my quick search didn't yield much. I am thinking ahead toward my future catamaran power management and seeking advice regarding solar. I am planning to have a frame extending from the rear of the main sheet traveler on the cockpit roof extending outward over the dinghy davits. I want big solar to help with big lithium. I am looking for proven efficiency compared to size, weight and longetivity. I visited one or two booths in boat show">Annapolis boat show that were selling solar. Marine dedicated solar is expensive! I am pretty sure most cruiser using hard panels are installing panels that were not necessarily designed for the marine environment. What about bifacial panels? I see them more and more and they couldn't make more sense on a boat. But, from what I see, they are heavy. Weight have a big roll here since I ham hoping to fit 6 x 475+ watt panels on a frame. The weight is adding up...

From what I can see, one of the best panel for the job is Sunpower SPR-MAX6-475COM . It is 475 watt, 50 Lb, 81" x 41" (6 panels: 2850 watt, 300 lb, 138 SF).
One of the best bifacial panel I see is Qcells Q.PEAK DUO XL-G11/BFG. 585 watte, 76 Lb, 95" x 45" (5 panels 2925 watt, 380 lb, 148 SF).

This is internet experience on manufacturers "optimal", not sure how real, conditions. What about real life experience? Any cruiser can share some of his/her experience with panels on a frame? Again, I am looking for top quality, proven hardware but open for anything that make sense. Thank you for sharing!
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Old 26-11-2022, 08:56   #2
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Re: Ultimatesolr panels

LG pulled out of the solar market last June sadly, just as I was about to buy a 440w bi-facial panel from them. Panasonic also produced bi-facials, but they seem to be on radio silence this side of the pond. You might have better luck state side. I ended up with a pair of 295w Perc panels instead. They are run of the mill panels but at a good price and available in the UK. There is still a shortage of panels due to European energy prices doubling.

If its still hosted, LG had a really good website that explained in clear terms how bi-facial panels worked and how to maximise the output. In brief, saltwater doesn't reflect sunlight very well, but you know this because the sea warms up each Spring, well that heat comes from sunlight. The good news is white GRP does reflect sunlight well. So does snow apparently. LG were quoting between 15-26% increases above the rated panel due to absorbing sunlight on the back of the panel. That puts a 440w panel into 500w territory.

I have been following Andy on YT (Off Grid Garage) who has just invested in a shedload of Hyundai shingled 400w panels which is interesting. They are available as 415w for the same size here in the UK. Are these new panels a huge improvement over existing panels, he says not, but they are more efficient therefore an improvement and the lack of buss bars between the cells an interesting design change. Because the cells are shingled like slates on a roof the bottom of one cell makes the electrical contact with the top of the next and so on.

Not sure Q Cells are in the same league as Sunpower but the numbers are tempting. Also what's the difference between a marine solar panel and one for a house? A big increase in price perhaps? personally I think they are all the same and come off the same sort of production lines in China. The market is in commercial and residential installations, not a few yachts.

In terms of what you might achieve, we saw 278w out of a previous 300w solar panel, in really good conditions. Surprisingly, we also saw 60w in the rain during one mid day down pour in August. Sadly in the depths of winter we have also seen 14w from 300w mid afternoon with the sun low in the sky and the panels facing the wrong way for our pontoon mooring.

Be interesting to see what you choose.

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Old 26-11-2022, 16:21   #3
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Re: Ultimatesolr panels

Thanks for the reply. Yes, marine panels are better protected from the elements and the salty environment according to the people in the boat show but I agree with you and won't bother to pay the extra $$$. Also, I am based in the New York City area and in the winter the sun doesn't go up high in the sky and we get loads of of cloudy days (on my prior power boat I installed 3 x 100 watt panels to extend the life of my house battery so I hear you about the UK winter). If my plan will se the light of day, I will cruise mainly in the tropics so year round high sun in the middle of the day should be plentiful.
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Old 26-11-2022, 18:18   #4
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Re: Ultimatesolr panels

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Originally Posted by hezi973 View Post
Marine dedicated solar is expensive!
Sunpower is top of the range and Qcell is also a good brand, maybe not in the same league as Sunpower.
Personally I'd go for the highest wattage rated / area residential panel at a reasonable price, There is a (salt?) rating on some residential panels for use in coastal environments so this would be something to check on the panels available in your area.

If you want the extra performance from bi-facials then just buy what's available, there's not a lot of options but given the amount of solar you are planning, do you really need them? Could always plan a transom extension to offset the weight. Win win.
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Old 26-11-2022, 18:31   #5
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Re: Ultimate solar panels

Renogy panels are reasonable. About $1000 for a 550w panel. Or even less if you buy the equivalent in flexible panels. You can also buy a kit.

Yes, the frame can be expensive, but you don't necessarily need a frame. With a monohull, you are usually limited to the space you describe - putting the solar panels over the bimini or davits. However, since you are looking at buying a catamaran, you have a lot more surface area and can put flexible panels on the roof or the amas. They are strong enough to walk on.

I don't see what would be a difference with so called marine panels. Water? Every solar panel is designed to withstand rainfall. They have to be outside, after all. Salt corrosion - maybe, but it would have to be a hell of a lot of corrosion, and if that is a problem you can just rinse them off from time to time.

And bifacial panels?? Someone wiser than me explain how these would be good on a boat. They would need to be exposed to light on both sides, so they would be mounted pretty precariously. That wouldn't make sense on a boat where you want everything fully secure from blowing away in a strong wind.
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Old 26-11-2022, 19:16   #6
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Re: Ultimate solar panels

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Renogy panels are reasonable. About $1000 for a 550w panel. Or even less if you buy the equivalent in flexible panels. You can also buy a kit.
Sounds expensive, Sunpower should be around $1000/kw and Jinko about half that.

Quote:
And bifacial panels?? Someone wiser than me explain how these would be good on a boat. They would need to be exposed to light on both sides, so they would be mounted pretty precariously. That wouldn't make sense on a boat where you want everything fully secure from blowing away in a strong wind.
PERFORMANCE, significant performance improvement in the 10-20% range over standard panels of the same area.They get light to the exposed underside due to reflection off of the water or boat surfaces. Yes, many boats mount them "precariously" on a custom solar arch either above or incorporated with the davits.
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Old 26-11-2022, 20:01   #7
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Re: Ultimate solar panels

Quote:
Originally Posted by hezi973 View Post
I want big solar to help with big lithium.

Plan on solar over a large area, which is feasible on a cat.




Quote:

I am looking for proven efficiency compared to size, weight and longetivity.

Your choices are commodity panels, which are cheap and last a long time, or bespoke flexible marine panels, which cost 10x as much and don't last very long, but have less windage. Or you can use a mixture of these.



In the present market, commodity panels have good efficiency. You can get, perhaps, 10%-20% more efficiency, by paying 2x as much.


Quote:
I am pretty sure most cruiser using hard panels are installing panels that were not necessarily designed for the marine environment.

Correct. The experience is that commodity-grade rigid panels will last for many years on a sailboat on the ocean. Flexible panels, even the good ones, have a much shorter life.



Quote:

What about bifacial panels? I see them more and more and they couldn't make more sense on a boat. But, from what I see, they are heavy. Weight have a big roll here since I ham hoping to fit 6 x 475+ watt panels on a frame. The weight is adding up...

On a sailboat, panels are ordinarily installed flat to minimize windage. There isn't much to gain from bifacial panels because they face a shadowed surface.


Quote:
This is internet experience on manufacturers "optimal", not sure how real, conditions. What about real life experience? Any cruiser can share some of his/her experience with panels on a frame? Again, I am looking for top quality, proven hardware but open for anything that make sense. Thank you for sharing!

We are at a point where, with larger boats and cats, commodity panels are the clear deal. You can spend more but if all you get is 10%, 20%, even 30% more power, why do it?



With a mono if you are trying to keep windage under control then the situation is different because you have to use nonstandard, smaller panel sizes to fit the space, and have to consider flexible and walk-on panels to get sufficient power.
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Old 26-11-2022, 20:27   #8
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Re: Ultimate solar panels

The most common thing you see on new privately owned cruising cats is a 1200-2400 watt solar array off the stern made from 400watt panels.

The most common are 400 watt residential panels from LG or Sunpower. Bifacial disappeared about 18 months ago due to supply chain problems and manufacturers walking away from bifacial. I'm not sure if they've returned in useful numbers. It's hard enough to even get the regular ones. Waits can exceed six months.

Just about every marine stainless fabricator has a solar arch design he likes. These vary a lot as many marine stainless fabricators have no training in engineering or finite element analysis. This often results in a very heavy frame and/or one that bucks around at sea. In large seas there's a lot of torque and moment on the frame so you need a well designed frame to keep the panels from bending and possibly breaking internal solder joints. Try to copy a design that's been proven to survive offshore conditions. Oh - and a custom stainless arch fabrication and installation (they are all custom) is expensive -- often exceeding $10,000 without the panels.

Using panels larger than 400 watts means a heavier arch because the panel extends farther out - making it harder to keep stable. The weight of the stainless arch can be much more than the panels. The Sunpower 400 watt is 72" long. Going up to the 475watt means 81" long which will likely require bigger and heavier tubing. The 95" length of the Qcells will require a massive framework hanging off your stern that will be ugly and the weight will hurt sailing performance.

Some boats augment the solar arch with flexible panels forward. The problem is shading from mast, boom and rig. Typically the panels on the port side of the mast will work half the day and the panels on the starboard side the other half. 10% shading will drop a panel's output to essentially zero. And flexible panels continue to have poor reliability - rarely lasting more than two years if used in southern waters. Up north they can last quite a while. It's also common to find when removing the flexible panel that the panel heat has discolored the deck gelcoat. Expensive to repair unless you just stick down another panel of the same size. If buying flexible panels use a vendor known for good warranty service - you'll probably use it.
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Old 27-11-2022, 02:12   #9
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Re: Ultimate solar panels

we have 1.4kw solar with 3 x 370w yingli panels mounted on the roof plus another 2 smaller panels of unknown parentage. the 3 yingli panels + 1 victron regulator cost €678.53 delivered which pretty cheap here in tahiti

routinely see 55-60 amps output

we do not have a solar arch as no need and use a boom crane for the dink. panels are mounted on spacing bearers onto the cockpit roof. it's important to keep airflow under the panels for cooling. for me this rules out flexible panels

however to my mind what is at least as important as your panels is how the regulators are set up. we have 3 seperate victrons for optimum efficiency n minimum effect from shading

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Old 27-11-2022, 02:44   #10
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Re: Ultimate solar panels

You may find this arch system interesting that you can assemble yourself without welding and they send it to you as a kit. It also includes a panel inclination system that greatly increases its efficiency. And now there is a good offer until the end of the year:
https://www.autocazantes.com/en-gb/s...rgy-fix-basic/
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Old 27-11-2022, 03:41   #11
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Re: Ultimate solar panels

I would not recommend flexibles at all they are not robust develop hot spots and fail with alarming regularity.
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Old 27-11-2022, 04:30   #12
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Re: Ultimate solar panels

I have used normal domestic rigid solar panels for over 20 years without a single issue or failure and no corrosion. You just have to take the normal marine precautions when disimilar metals are used to mount them to pevent electrolytic corrosion i.e. using insulated washers, plastic rail clamps etc. But that would also apply to so called 'marine' panels

The only slight concern I have is regarding the shallower frames (30mm vs 40+ mm) used on more recent panels coupled with their larger size so you have to ensure mounting at the manufacturers recommended positions to prevent undue flexing. You may have to devise a sub frame to achieve that.
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Old 27-11-2022, 05:04   #13
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Re: Ultimate solar panels

Who makes a marine panel? From what Iíve seen itís really hard to find a company that will warranty a panel installed on a boat or one thatís close to a salty environment. But then again Iím guessing there are very few warranty claims on rigid solar panels?
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Old 27-11-2022, 07:06   #14
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Re: Ultimate solar panels

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The most common are 400 watt residential panels from LG or Sunpower.
Sadly LG have walked away from the market.

Quote:
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Using panels larger than 400 watts means a heavier arch because the panel extends farther out - making it harder to keep stable. The weight of the stainless arch can be much more than the panels. The Sunpower 400 watt is 72" long. Going up to the 475watt means 81" long which will likely require bigger and heavier tubing. The 95" length of the Qcells will require a massive framework hanging off your stern that will be ugly and the weight will hurt sailing performance.
Certainly a concern on a 31ft yacht. Our arch weighs about 11kgs plus 2 x 295w panels at 17kgs each. I have a bit of work to do to make it a bit more robust. Its was fine with a single 300w but doubling that a week ago means it now moves when shaken hard.

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Old 27-11-2022, 10:43   #15
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Ultimate solar panels

I really little between ď good ď and generic brands these days. I suspect they all hail from a common few Chineseís production lines.
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