Are Solar Mats usable on a yacht?

[coopec43]

Helen is a ketch and therefore finding places for solar panels can be difficult. Would a 380W solar mat attached to the stanchions/lifelines be a proposition?

https://www.batterymate.com.au/produ...a&gad_source=1

[Benz]

Many around here use the Solbian flexible panels that you can walk on. But they lay them flat on decks and cabintops. Not sure how you'd secure a mat securely enough to stanchions so it wouldn't flex a lot.
Most boats in my experience with rail-mounted panels have a way of trimming them so they catch the sun better. Would your mat be trim-able?

[coopec43]

Originally Posted by Benz

Many around here use the Solbian flexible panels that you can walk on. But they lay them flat on decks and cabintops. Not sure how you'd secure a mat securely enough to stanchions so it wouldn't flex a lot.
Most boats in my experience with rail-mounted panels have a way of trimming them so they catch the sun better. Would your mat be trim-able?

I've only just seen the panels on an ALDI advertising brochure so I have a bit more thinking to do.

I'm sure they would have to be trim-able. Since Helen's system is 24V I'd have to install X2 side-by-side in series. Maybe I could use the hand hold and lower lifeline as mounting points (they'd just clip on)

Apparently, with household solar panels anyway, the angle of incidence is not so important with modern panels. (I'd check that out). I wonder if these panels have any diodes?

[coopec43]

This interests me.

"Why solar panels facing south make sense Solar technology has progressed rapidly in recent years, making it more efficient and cost-effective than before. Solar panels mounted on a roof facing south are now a viable option for many homeowners and businesses in Australia.
Nowadays, even solar panels on a somewhat shaded roof can be a worthwhile investment. And if your roof faces south – once referred to as the worst direction – it’s no longer a problem!"

https://www.trione.com.au/can-you-go...-facing-south/

[s/v Jedi]

If that picture is your boat then the first thing I would put my mind on is an arch on the stern for hoisting the dinghy and mounting a solar array on top.

Next is shade. Of you tie an awning over the mizzen boom then you could strap some of those portable solar panels on top of course

[Tedd]

Originally Posted by coopec43

Apparently, with household solar panels anyway, the angle of incidence is not so important with modern panels.

I'm guessing that, if you've seen some marketing around that subject, they're referring to the Incident Angle Modifier (IAM), which is the factor that determines how much the panel's efficiency at converting incident photons into electricity is affected by the angle of incidence. While a company wouldn't be lying by saying that an improvement in IAM would make angle of incidence "less important" the effect would be negligible because IAM is already nearly 1 for every panel out there. (And it can't be greater than 1.)

The reduction in panel output with angle of incidence is almost completely due to the reduction in the cross section of the rays of photons reaching the panel, not due to how the panel converts those photons into electricity. If you visualize the cross-section of the rays of light coming from the sun, it's easy to see that when the angle of incidence is zero that cross section is the same as the area of the solar panel. As the angle increases, the cross section of the rays gets skinnier and skinnier until, at 90 degrees, there's no cross section left. Nothing about the design of the panel can change that.

[s/v Jedi]

Originally Posted by Tedd

I'm guessing that, if you've seen some marketing around that subject, they're referring to the Incident Angle Modifier (IAM), which is the factor that determines how much the panel's efficiency at converting incident photons into electricity is affected by the angle of incidence. While a company wouldn't be lying by saying that an improvement in IAM would make angle of incidence "less important" the effect would be negligible because IAM is already nearly 1 for every panel out there. (And it can't be greater than 1.)

The reduction in panel output with angle of incidence is almost completely due to the reduction in the cross section of the rays of photons reaching the panel, not due to how the panel converts those photons into electricity. If you visualize the cross-section of the rays of light coming from the sun, it's easy to see that when the angle of incidence is zero that cross section is the same as the area of the solar panel. As the angle increases, the cross section of the rays gets skinnier and skinnier until, at 90 degrees, there's no cross section left. Nothing about the design of the panel can change that.

Exactly. The panels can reduce reflection but they can increase surface area.

A guy on YouTube did experiments with reflectors which did work but of course for hot climates it will burn the panel so requires cooling, giving up much of the gains and making it too complex for as so far the reflectors aren’t complex already

I have heard about experiments with bifacial panels, putting a reflective surface on top of a dinghy hanging under the panels etc.

[Ryban]

I agree that you'll have a better experience putting rigid glass solar panels on an arch, off a rigid cross pole between stantions (depending on your stantions), or on a dodger.

I've also been struggling where to place solar on our boat, and have a discussion here that might be helpful:
https://www.cruisersforum.com/forums...ch-283754.html
https://www.cruisersforum.com/forums...ml#post3875613

I haven't owned any sizeable fold-out or flexible panels from the last 4 years, but prior to that the consensus was generally that they just don't last nearly as long, and deterioate more quickly in the conditions they face on a boat if they're going to be used all the time. A lot of them also say they can be walked on, but in reality, this starts to damage the panel, sometimes cracking PV cells. I've had cells crack on flexible panels in big blows, so they need to be firmly secured in a way they cannot flex.

But again -- manufacturers may have gotten better in the interim.

[JBP]

Most people use rigid (glass) panels on the lifelines. They can be tilted as desired. There are some carbon fiber backed panels that are much lighter than glass intended for lifeline use, but they are very expensive. https://www.lightleafsolar.com/

I use one of those folding solar panels. I lay it out on my Bimini when I want some extra power. Lashed down it has withstood 50+ knots. I like it because it folds down into a convenient size for storage when not in use.

My fixed panels are the Lensun semi-flexible fiberglass backed panels on deck which can handle being walked on and are a lot less expensive than the Solbian. I've considered hanging some of these on the lifeline, but I don't think they are really strong enough to support themselves in any kind of wind.

[fxykty]

We had a 300W solar blanket (5 panels that fold up into a relatively convenient carry case) that we used on our tramps or on the cabin roof when sailing and at anchor. The blanket could be positioned to catch the sun, especially when the fixed panels are mostly shaded (such as when sailing with the sun on the bow). It could be angled for early morning/late afternoon production. It had decent tie down points and would stay out under 25 knots AWS. Anymore than that and we put it away so as not to have to worry about it.

Unfortunately, it didn’t last - only 5 months of near daily use and it developed a short between two of the panels. It was a warranty issue but shipping was going to cost more than the blanket was worth.

We will get another one eventually - the shaded fixed panels when the sun is on the bow is a compelling use case for moveable panels.

[nuku34]

Re mounting panels on the lifelines: IMHO not a good idea if you plan to go anywhere with waves over a 1m high. A breaking wave has tremendous force and will trash the panels and bend the stanchions. Most neophyte sailors have no idea of the damage the sea can do. Sooner or later you WILL experience a breaking wave on the beam.



Mounting the panels on an arch or on the top of the dodger is much better.


An alternative is the setup on my Joshua type 40ft ketch: we mounted narrow long glass solar panels with custom made alloy frames between the masts and the cap shrouds about 2m off the deck; a person could walk under them. So 4 panels.
The mast side of the panels mounted and pivoted on a bolt that went through the mast and stuck out about 70mm on each side. The bolt went through the frame a bit forward of the mid point. The cap shroud ends had custom mounts made from SS bulldog clips.The panels could be rotated to any angle. We generally kept them horizontal when beating to reduce windage, but at anchor or reaching or running we would adjust the angle during the day.
These 4 panels went across the Drake Passage to Antarctica, through the Magellan Straits, and through a category 9 tropical storm in the Coral Sea with NO damage.
"Sundowner" is a cutter ketch with 3 sizes of high clewed jibs on the forestay. The clews of all the jibs are higher than the panels so there is no interference between clew and panel when tacking.
Its a simple and elegant solution well suited to ketches 40ft or over.
Attached are 3 photos. 2 of Sundowner which shows the placement of the panels. The 3rd is her sister ship after doing a backward pitch pole off a 40ft wave in the Med (not the Southern Ocean).

[NBs]

My experience with the folding panel is the attention of the fabric on the edge, which for the first season lost its color from UV light and I suspect the stitches will fade this year. Examine what kind of fastening possibility can be found in the corners of the panel, it is essential because the wind will catch on with force and if the fasteners are poor you will be in trouble. As such, the panel has been good and handy in my own use.

[coopec43]

Originally Posted by s/v Jedi

Exactly. The panels can reduce reflection but they can increase surface area.

A guy on YouTube did experiments with reflectors which did work but of course for hot climates it will burn the panel so requires cooling, giving up much of the gains and making it too complex for as so far the reflectors aren’t complex already

I have heard about experiments with bifacial panels, putting a reflective surface on top of a dinghy hanging under the panels etc.

I came across this article while trying to find where I read that with modern solar panels the orientation to the sun's rays was not so important as (I think) the glass was cut in such a way as to change the "angle of incidence". (I'll keep looking)

I thought you could be interested in this if you haven't already seen it.

https://www.eco-greenenergy.com/bifa...-your-project/


Bifacial

– Double-sided and absorb energy from both sides
– Higher energy output per square meter, up to 30%
– Can be set up at any angle
– Longer warranty up to 30 years

[s/v Jedi]

Originally Posted by coopec43

I came across this article while trying to find where I read that with modern solar panels the orientation to the sun's rays was not so important as (I think) the glass was cut in such a way as to change the "angle of incidence". (I'll keep looking)

I thought you could be interested in this if you haven't already seen it.

https://www.eco-greenenergy.com/bifa...-your-project/


Bifacial

– Double-sided and absorb energy from both sides
– Higher energy output per square meter, up to 30%
– Can be set up at any angle
– Longer warranty up to 30 years

Of course I meant they can NOT increase surface area.

That article explains reduction of reflection by bending the beams that hit the surface to more perpendicular to the panel. But it is impossible to bens rays that pass besides the panel to hit the panel instead of missing it. Even though those rays would be caught with the panel aligned correctly.

[coopec43]

Originally Posted by s/v Jedi

Of course I meant they can NOT increase surface area.

That article explains reduction of reflection by bending the beams that hit the surface to more perpendicular to the panel. But it is impossible to bens rays that pass besides the panel to hit the panel instead of missing it. Even though those rays would be caught with the panel aligned correctly.

Aren't they saying some rays will hit the top layer of the panel directly from the sun but other rays will miss the panel, hit the "ground albedo" and be reflected onto the bottom (back) layer of the solar panel?