Which solar panels?

[FlyWright]

I went with 5x100W Renogy rigid panels since I was using rail mounts on my fwd rails plus one more that is able to be repositioned as needed. I found that my panel size constraints limited the panel choices for me since I wanted the panels to stow between the SS fwd rail and the caprail. I've got no regrets w/ the Renogy panels or their MPPT controller.

 

[guy with a boat]

I wouldn't be comfortable with just relying on adhesives to mount a metal bracket to the deck with all the flexing from the boat while underway and flexing from heat expansion and wind…
Hollywood

A middle ground on the attachment issue is to bond wood or FRP pads to the boat and then screw the metal brackets to those pads. That avoids penetrating the deck (which can eventually leak) and gives more surface area for the adhesive than the metal brackets would. A little flex in the adhesive under the pads might even be helpful to accommodate the movement you mention. Do this using 3M 4000 or 4200 and the adhesive connection will be stronger than the rest of the mounting system.

 

[JDCAVE]

I wouldn't be comfortable with just relying on adhesives to mount a metal bracket to the deck with all the flexing from the boat while underway and flexing from heat expansion and wind…

I’m not lying awake at night worrying that 4200 mounted panels will fly off any time soon. They’ve been up 5 years and there is no evidence of deterioration of the glue or mounting brackets. I just did not want to be putting screws through the roof. A colleague used a type mounting tape and he’s quite pleased with how that has worked for him.

Jim

 

[rslifkin]

For strength of the mounts, I did the math on 4000UV. Even if I got 10% of the spec-ed bonding strength of the adhesive, I've got 24 sq inches holding each panel down. That would give (assuming 10%) enough strength to resist ~790 lbs of sideways load trying to shear the mounts off the deck. No way will that happen in any amount of wind, especially as short of a strong headwind while up on plane, wind will always be pushing the panels slightly downwards (due to the crown of the deck). Lifting strength is a bigger concern, but there's nothing that would generate significant upward load on the panels, so I'm not too worried about that.

 

[mvweebles]

I know of several camper van owners who attached flexible panels with heavy duty scotch brand outdoor 2-sided tape. Only issue has been the tape is so strong the panel is damaged if removed. Given that camper vans spend a lot of time at freeway speeds, it's a decent endorsement for the tape.

Peter

 

[dhays]

So VHB tape is a no-no? Seems easiest way to do it and no breaching of the skin of the deck. Wouldn’t think there’s enough space underneath to allow growth but also not enough space for ventilation.

I used VHB tape with 4200 to mount my solar panel on the top of my PH roof. The roof is smooth fiberglass, not non-skid.

I am on my iPad so can’t find my thread on how I installed my solar panel, but I use some aluminum L brackets to mount them. I made them so I could easily angle the panels to clean underneath if desired. (Not that I really keep a clean and shiny boat).

I used the VHB tape and then used 4200 to seal the edge. It has stood up really well.

 

[koliver]

So I’m hearing replace them?

In 10 years the output per panel has increased dramatically. Even since 2018, when I put mine on, I could get 160 amps per panel, and now I could get panels that put out over twice as much in a similar footprint. Then add on any losses due to age, cracks, etc, so all adds up in favour of renewal.

 

[FF]

"I wouldn't be comfortable with just relying on adhesives to mount a metal bracket to the deck with all the flexing from the boat while underway and flexing from heat expansion and wind."


Many parts of a modern airliner are glued together. With good glue.

 

[Hippocampus]

Now thinking 4000 or 4200. ?which one? Come to think 4000 better in marine applications. True?
Thinking a long rail of G10 or Starboard to allow more surface area for the glue. That way camber of the deck isn’t an issue as it would be with pads. Want to avoid punctures of the skin if possible. Thoughts?
Question if I should have frame TIG welded or bolted. Want panels elevated 28” as that’s sufficient for anything I might want to store under them and won’t interfere with sight line from flybridge to stern when docking or from pilot house looking aft. Have decided to not have them tilting as too much complexity and expense.
So far finding availability is a problem for small orders of panels. But liking the Panasonic mono crystalline.

 

[rslifkin]

I used 4000UV as according to the 3M docs, it bonds more strongly to aluminum than either 4200 or 5200. Plus it's more UV resistant, so any that's visible on the edges should hold up better.

I'd go for a bolted frame, that way it's easier to adjust for any future changes as well as to take things apart for access if needed.

For panels, check with solaris-shop.com. That's where mine came from and for stuff they have in stock, they had no problem selling me just 2 of them.

 

[CaptainDC68]

Big differences on prices between the brands. Renogy makes good solar panels, for very good prices. Believe Home Depot carries them.

 

[hollywood8118]

"I wouldn't be comfortable with just relying on adhesives to mount a metal bracket to the deck with all the flexing from the boat while underway and flexing from heat expansion and wind."


Many parts of a modern airliner are glued together. With good glue.

I totally agree, they're done in near perfect lab conditions by professionals and the engineering behind the bonds are designed with a safety factor of 5.
The addition of adhesive mounts on our boats is typically done by non pro's, in outdoor conditions and may have shortcuts taken to get it done in a hurry.
If it is done correctly even in not so great conditions and the prep is right it should work fine. With my thoughts more on Bluewater conditions, "should" isn't where I'm comfortable.

My choice would be more related to what the structure of the deck is ( solid vs. cored or?)

Hollywood

 

[Bob Cofer]

The latest generation of semi flexible panels are pretty impressive. This is mounted to the hood of my Land Rover with VHB tape, sealed with Sikaflex around the edges and connected to an MPPT controller under the hood. A Group 49 AGM battery keeps the fridge/freezer running 24/7 year round. Not bad for our weather conditions.

 

[twistedtree]

Now thinking 4000 or 4200. ?which one? Come to think 4000 better in marine applications. True?
Thinking a long rail of G10 or Starboard to allow more surface area for the glue. That way camber of the deck isn’t an issue as it would be with pads. Want to avoid punctures of the skin if possible. Thoughts?
Question if I should have frame TIG welded or bolted. Want panels elevated 28” as that’s sufficient for anything I might want to store under them and won’t interfere with sight line from flybridge to stern when docking or from pilot house looking aft. Have decided to not have them tilting as too much complexity and expense.
So far finding availability is a problem for small orders of panels. But liking the Panasonic mono crystalline.

Don't be tempted to use Starboard because it doesn't stick to adhesives. I have use Asak synthetic trim board with success to creating mounting blocks for antennas and transom mount transducers on aluminum hulled RIBs. They were glued with 5200, as I recall.


I think with the panels standing so far off the deck there is little to no benefit to tilting unless you need to stand in that area for some reason.


Try AlteStore.com for panels and other parts. They will ship, or you can pick up at their warehouse in Boxborough, MA which isn't a huge drive from RI.


I'm using the Panasonic HIT+ panels and like them. They fit my space well, and that was the first consideration. But they are also at the top of the efficiency range at 20% so good power for the space.

 

[Mako]

That's a really nice looking installation @Bob_Cofer.

Back to OP's questions, I would imagine that there has been degradation of his panels if they are 10 years old. Probably some studies out there if he wants to Google it.

 

[sbman]

The improvements to output per sq/ft in 10 years is pretty significant, if you want more solar in the same space, definitely replace. I've thought about hinging mine so I can get under there to clean and I am probably going to do so, they are stood off on brackets, but no easy way to clean the deck underneath.

 

[slowgoesit]

Calculations figuring the shear/tension strength of 4200 or 5200 are missing one big factor . . . . . And that is what is the binding strength of the paint to the Aluminum roof/bimini? Or the gel coat to the fiberglass bimini or roof?

You can have the strongest bond imaginable to the paint protecting the aluminum (for example), but if the paint bond to the aluminum fails, the strength of the 4200/5200 means nothing!

 

[rslifkin]

Calculations figuring the shear/tension strength of 4200 or 5200 are missing one big factor . . . . . And that is what is the binding strength of the paint to the Aluminum roof/bimini? Or the gel coat to the fiberglass bimini or roof?

You can have the strongest bond imaginable to the paint protecting the aluminum (for example), but if the paint bond to the aluminum fails, the strength of the 4200/5200 means nothing!

That's why I picked 4000UV over 4200/5200. I was looking at the numbers for bonding strength to various substrates, not just the tensile strength of the cured adhesive. Bond to aluminum was the limiting factor, not the bond to gelcoat.

 

[Hippocampus]

Pretty much decided to replace core with pads of G10 at points of attachment. Tap the G10 for screws. Between that and thick outer skin believe that’s plenty strong even with increased wind loading from raising the panels.

 

[Simi 60]

We used 50mm thick hollow section recycled plastic garden sleepers cut into 100 x 150 pads.
Sanded paint down to glass
Glued down with sikaflex pro

They have seen 80+ knots and been there 5+ years now

 

[Barrie]

I used four stainless steel hinges with removable pins. I had access to the ceiling and was able to bolt through. Here is a link to the hinge. I would send a picture if i could figure out how to attach it.

 

[Cedar22]

I have 81 solar panels located on a house, barn and shed. Had 4 flexible solar panels on a previously owner NY 37 (mounted on the flexible flying bridge Bimini). I have been advised that it is essential (especially with "hard," fixed solar panels) to have air circulating under the panels to provide cooling. Without air circulation/cooling, sections of individual panels get too hot and tend to malfunction or "burn out." I also believe in purchasing the highest quality, most efficient solar panels available at the time of purchase. The efficiency and cost of solar panels changes almost weekly! Note the guarantee that comes with the better or best solar panels.

 

[Hippocampus]

Had solar on last house and have it on our new build. Houses have an advantage over boats as there’s always a thermal draft on a slanted roof even in the absence of wind. A small offset is more than sufficient for a roof installation. Not so sure with a boat and horizontal panels on a deck. Think there even though the deck under the panel will be cooler than then the surround you need more of an offset. One of the reasons I’m thinking of raising them.
Still shopping. So far due to energy density, weight, price per watt, guarantee, availability liking the Panasonic and the Mission solar.

 

[Taras]

If you've seen Parlay Revival (youtube) recently, you'll see that Collin is building a hard solar panel "hard top" made of just tubing, hard panels and a few fiberglass pieces to fill in the gaps. Made me reconsider actually even needing a bimini top to install the panels to......has anyone here considered engineering a tube frame that the panels afix to and then sealing the panels together to make it water tight so as to not leak when it rains? You could then hang your eisenglass off the edges of the panels. Just thinking out loud Basically, your solar panels become your hard top. Wouldn't be able to walk on it obviously, but engineered with the right tubing substructure, it could work?

 

[sbman]

If you've seen Parlay Revival (youtube) recently, you'll see that Collin is building a hard solar panel "hard top" made of just tubing, hard panels and a few fiberglass pieces to fill in the gaps. Made me reconsider actually even needing a bimini top to install the panels to......has anyone here considered engineering a tube frame that the panels afix to and then sealing the panels together to make it water tight so as to not leak when it rains? You could then hang your eisenglass off the edges of the panels. Just thinking out loud Basically, your solar panels become your hard top. Wouldn't be able to walk on it obviously, but engineered with the right tubing substructure, it could work?

I've thought about that, but main issue I see with it is that there is no "standard" for panel size, so your frame becomes intimately connected to the panels with no replacement options. As soon as the particular panel you are using is no longer available any damage/crack/issue that happens 3-4 years from now, you are likely out of luck and having to modify either a new panel or the frame to fit. Plus the cost of stainless tubing is crazy! I think you could build a more traditional fiberglass hardtop with solar mounting in mind for similar if not less money.

If you didn't care too much about completely sealing it up for rain, the tube/panel hardtop could work with a rail system to alleviate the sizing issues and still allow a panel to be swapped out later without much issue.

 

[Hippocampus]

There’s gutter systems to fit under the cracks between the boards of a deck on a house. Given the variance in size between house panels isn’t that great such a or similar too system would allow it to serve as a Bimini top. Simpler would be tracks. Panels close together with butyl tape between them.
That not we’re doing. Just want to raise the panels high enough to store kayaks and such under them. Was thinking an aluminum tube to form a rectangle. Weld at one place so continuous. Bend at corner of large enough radius to allow rigidity. Four of them to form a open box bolted together. One for each panel. To add strength the boxes could be bolted together. The tubes would raise the kayaks off the deck enough to prevent abrasion of the deck. Being open sided wind resistance is decreased and ventilation preserved. Can place a dyneema loop wherever necessary for tie downs to secure things. KISS and easily removable.