Sliding Solar Panels on Cal 28 pushpit

[Thorpydo]

I am planning on mounting four 85W solar panels on the pushpit of my Cal 28. Two panels per side, configured on slides so that both panels can be out catching the sun, or they can be retracted and folded down, out of the way. The attached picture should make this clear.

I am looking at ET 95W monocrystalline solar panels, specifically ET-M53695, but am open to suggestions. They are ~47"x22", 36 cell.

The slides are 500lb stainless drawer slides, Sugatsune ESR-10-24

I am unsure on the wiring and charge controller.

I think I would like to wire all four in parallel. Chances are good that the backstay will shade one pair of panels. I have read about people wiring a pair in series and then two of those pairs in parallel. I like that approach except that it means that efficiency would suffer dramatically when I have the second panel tucked behind the first and I'd like to be able to do that.

I'm also unsure on the charge controller. I understand that mppt charge controllers benefit most when feed a high voltage. This wont be the case with 12v panels wired in parallel, but I believe there will still be some gain. How much?

Blue Sky Solar Boost 3024iL makes a mppt charge controller that I believe has had some pretty good feedback and looks to fit the bill, but at $350 I could get two of genasun's GV-10-Pb. That wouldn't work because the GV-10-Pb is only rated up to 140W and I could potentially feed it 190W with two 95W solar panels, but the point is, that I wonder what the advantage is to multiple charge controllers?

Wiring: The panels have MC4 leads attached. I would probably buy a couple MC4 cables, cut them in half and lead these through the deck with some sort of connector (ideas please?) and then terminal block to a heavy gauge wire. Is it better to place the charge controller closer to the batteries or the solar panels? What kind of fusing will I need?

Thanks,
Adam

[sarafina]

Has your traveler been modified from the original? It seems like the panels might interfear with the traveler.

Also access to the lazarette would be problematic, if you have your motor there. If you have an inboard set up then that wouldn't be affected.

And I SO want pictures when you get this installed! And detailed instructions... We are still figuring out a solar system ; -)

[svholdfast]

Hi Adam I have a few thoughts.
I love the slide idea thought about using it, but 740 watts is enough.
I had my panels wired in series(4 x 185) with mppt controller handling the voltage difference which was fine until the controller stopped working in the Bahamas. So i bypass the controller and went from 50 amps to 16 because of the voltage miss match. Now the panels are wired parallel with Heavy wire. If you look in your controller manual you will find the closer the panel vs battery voltage is the better controller efficiency.

Hope this helps
sv Hold Fast

[noelex 77]

2 85 or 95w panels are reasonably large with a fair amount of windidge. I am not sure your mounting system is adequate even if you limit the deployment, by folding 2 of the panels up. I think you are going to need a bracing tie down system etc.

There is a lot of debate about series and parallel conection, but in your case parallel will definatly be best.
The gains from MPPT on a boat are very small. Think in the order of 5 or 10% for the very best controllers. The cheap ones with poor tracking I think are often worse than the simpler non MPPT models.
The blue sky controler is resonable. This one looks better to me

Rogue Power Technologies

Make sure you are not going to fit more panels, because these controllers are only just big enough.

The outback 60 is a better controler again, it would give you more room to grow, but it's great deal more expensive.

The gains for MPPT are a bit less for parallel conection , but if you use reasonable wiring ( this will be thick ) the difference is not significant. With parallel conection it doesn't matter much where you mount the controler, but nearer the batteries is slightly better.

The mc4 connectors are not ideal for a boat I cut them off and use solder and heatshrink to join the wires, but you may void your warranty.

[Thorpydo]

sarafina,

Has your traveler been modified from the original? It seems like the panels might interfear with the traveler.

Also access to the lazarette would be problematic, if you have your motor there. If you have an inboard set up then that wouldn't be affected.

And I SO want pictures when you get this installed! And detailed instructions... We are still figuring out a solar system ; -)

These are great points. I don't know if the traveler is original or not, but it is on a track just in front of the lazarette. I think the panels could interfere with the mainsheet but the panels could also be moved aft a bit on the rail.

I do have and outboard and use the well but I don't see these panels getting in the way. In what would do you think they would?

I will make sure to take pictures of the build, but only in exchange for pictures of your galley remodel. That is my next project after this one.

svholdfast,
Interesting. I have read about offshore sailors preferring 12v panels in parallel for exactly that reason- the mppt controller failing. Nice to know that it actually happens (I think).

noelex 77,

I think you are going to need a bracing tie down system etc

Can you please elaborate on what you suggest? I agree that there is a large moment on the rail clamps and a support bar or brace could be helpful, but I would still like to be able to articulate the panel into the sun direction.

The blue sky controler is resonable. This one looks better to me. Rogue Power Technologies

Why does the rogue look better to you? To me, they all look like a black box with a different dollar amount on them. I know what happens, big picture, inside, but not what qualities make one better than another. Besides maybe max operating conditions. I wonder what brand mppt controller failed on svholdfast?

The gains for MPPT are a bit less for parallel conection , but if you use reasonable wiring ( this will be thick ) the difference is not significant. With parallel conection it doesn't matter much where you mount the controler, but nearer the batteries is slightly better.

I have read that closer to the batteries is advantages in that the controller sees the battery level with less resistance and thus more accurately. It also may make sense in that the run from solar panel to controller is higher voltage and thus less lossey but that is marginal in my case.

The mc4 connectors are not ideal for a boat I cut them off and use solder and heatshrink to join the wires, but you may void your warranty.

I would like to be able to stow the panels so I like that connector. Any advice on how to pass it through the deck?

[noelex 77]

Originally Posted by Thorpydo

sarafina,


These are great points. I don't know if the traveler is original or not, but it is on a track just in front of the lazarette. I think the panels could interfere with the mainsheet but the panels could also be moved aft a bit on the rail.

I do have and outboard and use the well but I don't see these panels getting in the way. In what would do you think they would?

I will make sure to take pictures of the build, but only in exchange for pictures of your galley remodel. That is my next project after this one.

svholdfast,
Interesting. I have read about offshore sailors preferring 12v panels in parallel for exactly that reason- the mppt controller failing. Nice to know that it actually happens (I think).

noelex 77,

Can you please elaborate on what you suggest? I agree that there is a large moment on the rail clamps and a support bar or brace could be helpful, but I would still like to be able to articulate the panel into the sun direction.



Why does the rogue look better to you? To me, they all look like a black box with a different dollar amount on them. I know what happens, big picture, inside, but not what qualities make one better than another. Besides maybe max operating conditions. I wonder what brand mppt controller failed on svholdfast?



I have read that closer to the batteries is advantages in that the controller sees the battery level with less resistance and thus more accurately. It also may make sense in that the run from solar panel to controller is higher voltage and thus less lossey but that is marginal in my case.


I would like to be able to stow the panels so I like that connector. Any advice on how to pass it through the deck?

Frankly I am not sure how you will brace it. 2 telescoping SS " legs to triangulate the structure or at least 2 ropes. I think when you see 2x 90 odd watts of panels together you will be surprised by the size of it.

The rogue controler has a better MPPT implementation (I think) is slightly more efficient and a much better display. Its voltage set points are easier to adjust and it's also cheaper although that may depend on what deal you can get. The blue sky units are popular, but they seem to suffer more than fair share of failures. The Rogue is limited to 30 A which is only just OK. The blue sky is slightly higher for 12v
Your comments on the advantages of siting the controler close to the batteries is spot on, but the advantages are small if the wire is adequate. A model with display needs locating where the display can be read which limits the placement.

If you want to unplug the panels I would retain the connectors. A semi waterproof electrical junction box would provide a bit more protection from the elements, perhaps under the panels although this will increase the wire run slightly.

[Thorpydo]

Frankly I am not sure how you will brace it. 2 telescoping SS " legs to triangulate the structure or at least 2 ropes. I think when you see 2x 90 odd watts of panels together you will be surprised by the size of it.

I will continue giving this some thought and research. Others are bracing their panels and I'll probably be a copy cat. More research! (or suggestions from you guys!)

I have read up on the rogue ($325). Seems to be a well respected product and a one man show, which I dig. A great post can be found here where the inventor chimes in:
Rogue MPT-3024
I will email and ask about using 4 85 watt panels at 12 volts- 28 amps, which is very close to 30amps. I have read about sizing the controller 25% bigger than required because the panels can do more than advertised in cloudy days when there is a hole for the sun (getting both direct light from the sun and diffused light from the clouds).

Blue Sky is out.

Another option is the morningstar tristar TS-45. ($415) Looks to be a good product but lacks an LCD screen and instead relies on LEDS. Some people find this confusing.

Something like the outback flex mx60 is a great charger for a large array but will be less efficient than something more in my ball park current. Reason being, the components that allow for more current also require higher somethings and therefore, are more lossy. At over $500, it's out.

I do plan on retaining the MC4 connectors and a hiding them from the elements in a junction box is a good idea that I might have to implement. Any thoughts on how to pass the wires through the deck?

[noelex 77]

Originally Posted by Thorpydo

I will continue giving this some thought and research. Others are bracing their panels and I'll probably be a copy cat. More research! (or suggestions from you guys!)

I have read up on the rogue ($325). Seems to be a well respected product and a one man show, which I dig. A great post can be found here where the inventor chimes in:
Rogue MPT-3024
I will email and ask about using 4 85 watt panels at 12 volts- 28 amps, which is very close to 30amps. I have read about sizing the controller 25% bigger than required because the panels can do more than advertised in cloudy days when there is a hole for the sun (getting both direct light from the sun and diffused light from the clouds).

Blue Sky is out.

Another option is the morningstar tristar TS-45. ($415) Looks to be a good product but lacks an LCD screen and instead relies on LEDS. Some people find this confusing.

Something like the outback flex mx60 is a great charger for a large array but will be less efficient than something more in my ball park current. Reason being, the components that allow for more current also require higher somethings and therefore, are more lossy. At over $500, it's out.

I do plan on retaining the MC4 connectors and a hiding them from the elements in a junction box is a good idea that I might have to implement. Any thoughts on how to pass the wires through the deck?

The rogue will be fine with that amount of panels. The only problem is that you cannot add more ( without adding a second controler)

These sort of cable gland are the best. I have used a few brands with similar construction and all have been OK.

Index Marine - Cable Glands - Plastic

[Tellie]

I'd question the kitchen sliders. Even though the sliders are 304 what are the bearings? I'd think something along the lines of nylon rollers.

[Pete7]

Adam, does this picture give you any ideas? this is an 80w panel by the way.

Pete

[Thorpydo]

noelex 77,
Thank you for the reference.

Tellie,
The slides I've proposed are rated to 475 lbs/pair and have two sets of ball bearings per race, not nylon rollers. I do not expect the sliders to be the weakest link.

Pete7,
The picture looks to show two telescoping stainless poles to support the outer edge of the panels. The rail supports don't look like they allow the panel to articulate down to a horizontal position though. Are those poles telescoping? If so, where can I purchase them/ what are they called? Is this your sailboat?

I have read about solar panels mounted in a similar way using only the clamps across the rail to support the panels and in this case, after about a year, the clamps lost their friction grip and the panels would be able to rotate loosely around the rail. They didn't lose the panels, but were afraid that they might bang against the boat and break the glass. So it is an issue that I would like to address.

I see three separate solutions that all have there pros and cons.

The first, would be telescoping stainless tubing, rigidly attached to the panels and on deck or at the bottom of the push pit. I haven't been able to find a source for telescoping stainless so don't really know the limitations, both in travel, or how they fix a given length. A source for telescoping stainless would be helpful!

The second, would be a fixed length of stainless tubing. Rigidly attached to the deck, with several different mounting locations on the panel end. One mount for horizontal, one mount for tilted, one mount for folded. It might be difficult to make this work and will have to sketch something up in cad. I've included a picture to illustrate the support.

Option 3 would be a piece of hardware that is mounted rigid on the rail and has a positive locking mechanism to the panels. Pictures included. I like this option, but need to figure a way to keep the hardware from spinning on the rail (not a problem in the pictures due to orientation of the support tube).

[Pete7]

Originally Posted by Thorpydo

Pete7,
The picture looks to show two telescoping stainless poles to support the outer edge of the panels. The rail supports don't look like they allow the panel to articulate down to a horizontal position though. Are those poles telescoping? If so, where can I purchase them/ what are they called? Is this your sailboat?

Yes the photos are of my yacht. The telescopic poles are actually for a tonneau cover, all I did was chop the plastic ends off and used a different fitting. They are aluminium. Whilst this is a UK supplier, there must be a US sealer with something similar.

The panel could almost go to the horizontal but the dinghy gets in the way. Thankfully the 30. tilt is perfect for our pontoon and points the panel at the sun when we are away.

Aluminium Tonneau Pole Adjustable at Kayospruce Ltd

[Cheechako]

They should work great downwind if you put a swivel on them. Much easier than a spinnaker! Maybe a little hard on the elbows and head at times..... :>)

[Pete7]

These would give you a way of quickly releasing and lower the panel if the pole was attached to the end.

Cast Deck Hinge QR at Kayospruce Ltd

Final thought for now, how about the saddle of a small outboard engine less the leg and power head?

Pete

[callmecrazy]

Originally Posted by Thorpydo

noelex 77,


Option 3 would be a piece of hardware that is mounted rigid on the rail and has a positive locking mechanism to the panels. Pictures included. I like this option, but need to figure a way to keep the hardware from spinning on the rail (not a problem in the pictures due to orientation of the support tube).

Where do you find this hardware (the one in the picture)?

I've looked exhaustively online and cannot find them.