Solar Panels on small boat

[RupertW]

Rupert,
How's that?
Can you show me a flexible panel that generates more watts per square meter than a rigid? Flexible panels are prone to delamination as I know to my cost, whereas rigids can last for 20 years or more with output degrading less than 1% per year. I know this from experience. (well, 8 years so far).
Al

You posited it so please prove that decent flexis have worse efficiency - e.g Sunware or similar. A good flexi will last a decade on a Bimini which is why I chose the same as a neighbour’s boat as he’d had his that long. Same make for a few others in the marina.

They are very expensive I admit but I preferred that to diminishing my Stix with and arch, and being able to rapidly get the wind age off in a big blow at sea.

 

[Kelpie]

I might be able to mount them on the side if I replace the top wire with SS tubing.

I've seen people do this, but I don't really get the reason. Mine are just clamped on to the wire.
It was very easy. Drill two holes in the aluminium frame, use a bulldog clamp. It was fiddle getting the nuts done up because there isn't enough depth in the frame for a socket, so you need the right size ring spanner.
The weight of the panel does cause a little bit of sag in the wire. Nowhere near as much as tying on a fender.

Even on a 22ft boat I'd expect the stanchions to be about 600mm, so the space available for panels is about the same as a larger boat.

 

[Kelpie]

Hello, I have a very powerhungry little boat due to Laptop, Phone and Tablet usage.

How are you powering these, and have you chosen efficient devices to start with? There is a big difference between running a mains charger via an inverter, and using a 12v->19v car charger. Apologies if you're already doing this, but it's a very obvious way to slash your power budget.

 

[DangerousPirate]

Hm. I need to look for stern arches on ebay. I think thats a promising idea.

And are you positive that clamping them on the wire is good enough? With a wire I cant have the pictured system because you cant u-bolts and rotate the panel.

At the end of the day I would probably also get flexi-ones as additional power supply, but as the main panels Id just use rigid ones and mount them somehow.

The cheapest yet most effective way seems to be the T-Mount. It seems very easy to construct and yet looks very sturdy and safe. But i havent made up my mind yet.

 

[DangerousPirate]

How are you powering these, and have you chosen efficient devices to start with? There is a big difference between running a mains charger via an inverter, and using a 12v->19v car charger. Apologies if you're already doing this, but it's a very obvious way to slash your power budget.

So far I just have an extension to the local power grid in the marina. I try to get away from that so that I can have power while under way and at anchorages.

For now I focus on gaining energy, then on supplying it more efficiently.

 

[BabaYaga]

Another alternative that might be worth considering is the type that folds away to a 'briefcase'. These are rigid panels, but instead of an alu frame they are stitched into a canvas case. Something like this:
ACOPOWER 50W Foldable Solar Panel
I have two such 50W foldables laying on the coachroof when at anchor, sometimes also sail with them in light weather. Very easy to deploy and stow away.

 

[jdc]

I think a thorough look at power use is maybe the first step.

Looking at my devices:
My lap top takes 6W when I'm typing, and almost nothing when sleeping
My smart-phone / tablet takes 1W when being used, and again almost nothing when sleeping
My phone takes 9mW (the 400mAhr , 3.7V, battery lasts a week, 168 hours, so 0.4 * 3.7 / 168)

Total about 7W. Suppose you use them for 8 hrs each (a total combined active screen time of 16 hrs! - really??) That's 7 x 8 = 56 watt hours or 4.7 Amp Hours at 12V per day.

Suppose your panel sees the sun for 6 hours (winter, it will be double that in summer) that means the panel size has to be generate 56 Whrs / 6 = 9.3W. Suppose further that the solar panel only outputs 1/4 of what it says on the label, that still means less than 40W panel is adequate. Add a few inefficiencies (an extra 10% due to chargers for instance) and that's still less than a 50W panel.

So, since the OP is finding his batteries depleted, a quick audit of the actual consumptions may be in order: I find it hard to believe that the laptop, phone and tablet can consume very much: mine are an utterly insignificant fraction of my on-board electricity use.

PS: I used to design the innards of mobile phones for a living: we really, really, cared about power consumption!

 

[DangerousPirate]

Hm. I am not sure they will be sufficient. I look for a more permament solution.

Dont find any stern arches on ebay so I am just looking into the t mount swivel.

Top pole mount kit for solar panels 200W 260W 270W 300W photovoltaic

This one looks stable. So does this:

Universal solar panel pole mount kit for up to 54" wide, holds 2 100 watt panel | eBay

I just need those, and then fix a pole in the right length to the stern. Shouldnt be too complicated. What do you think?

I think a thorough look at power use maybe the first step.

Looking at my devices:
My lap top takes 6W when I'm typing, and almost nothing when sleeping
My smart-phone / tablet takes 1W when being used, and again almost nothing when sleeping
My phone takes 9mW (the 400mAhr , 3.7V, battery lasts a week, 168 hours, so 0.4 * 3.7 / 168)

Total about 7W. Suppose you use them for 8 hrs each (a total combined active screen time of 16 hrs! - really??) That's 7 x 8 = 56 watt hours or 4.7 Amp Hours at 12V per day.

Suppose your panel sees the sun for 6 hours (winter, it will be double that in summer) that means the panel size has to be generate 56 Whrs / 6 = 9.3W. Suppose further that the solar panel only outputs 1/4 of what it says on the label, that still means less than 40W panel is adequate. Add a few inefficiencies (an extra 10% due to chargers for instance) and that's still less than a 50W panel.

So, since the OP is finding his batteries depleted, a quick audit of the actual consumptions may be in order: I find it hard to believe that the laptop, phone and tablet can consume very much: mine are an utterly insignificant fraction of my on-board electricity use.

Well, knowing me I do use my laptop and phone a lot. I also plan on installing other things as well for the boat like a fridge and such. Its better to have too much though than too little.

My batteries dont charge at all. The only way I get juice in there is when I use a battery charger to power them up (so I can start the engine and run the nav lights)

Edit: Funnily enough I heard a similar calculation from others aswell,they bought like 75w and ended up installing more panels anyways. THere was this one guy here in a marina last summer, and this other guy who has a house in south east france. Funny lad. But it didnt check out.

 

[Kelpie]

And are you positive that clamping them on the wire is good enough? With a wire I cant have the pictured system because you cant u-bolts and rotate the panel.

Yes, I'm not sure what problems you forsee. The clamps I used were ones I found in the bottom of a tool box and are a bit big for the wire, so no matter how tightly I do them up they cannot clamp tight enough to stop the panel from swivelling. Well actually it's one bulldog clamp on the forward end, and one tube clamp on the aft end. Because that clamp sits next to an upright on the pulpit, the panel cannot slide.

I have sailed with this system in place with no worries at all. 35kt beats, big rolling swells whilst rounding Cape Wrath, etc etc.

How tall are your stanchions? That will be the biggest limitation on what size of panel you can hang on the wires.

 

[jdc]

...I also plan on installing other things as well for the boat like a fridge and such. Its better to have too much though than too little...

Well in that case the sky's the limit! Still do an audit of what you'll need 'tho. My fridge is about 1000 Whrs a day, my nav instruments around 250 Whrs, and my laptop and phone around 50Whrs a day, which suggest that the laptop (<4% of the total) isn't exactly the most significant factor in the decision making about solar panel size!

 

[Pete7]

Hm. I need to look for stern arches on ebay. I think thats a promising idea

Bit expensive, but might be worth a punt with a cheeky offer:

Boat a frame radar arch – Antiques & Collectibles – Ventnor, Isle of Wight | Facebook Marketplace

Better:

Boat canopy frame – Antiques & Collectibles – West Mersea | Facebook Marketplace

Interesting:

Stainless steel boat seat frame – Bicycle Accessories – Burnham on Crouch | Facebook Marketplace

 

[DangerousPirate]

Yes, I'm not sure what problems you forsee. The clamps I used were ones I found in the bottom of a tool box and are a bit big for the wire, so no matter how tightly I do them up they cannot clamp tight enough to stop the panel from swivelling. Well actually it's one bulldog clamp on the forward end, and one tube clamp on the aft end. Because that clamp sits next to an upright on the pulpit, the panel cannot slide.

I have sailed with this system in place with no worries at all. 35kt beats, big rolling swells whilst rounding Cape Wrath, etc etc.

How tall are your stanchions? That will be the biggest limitation on what size of panel you can hang on the wires.

What I mean is if its on the wire I cannot adjust the panels to the sun

Bit expensive, but might be worth a punt with a cheeky offer:

Boat a frame radar arch – Antiques & Collectibles – Ventnor, Isle of Wight | Facebook Marketplace

Better:

Boat canopy frame – Antiques & Collectibles – West Mersea | Facebook Marketplace

Interesting:

Stainless steel boat seat frame – Bicycle Accessories – Burnham on Crouch | Facebook Marketplace

Ah, Facebook Marketplace. Its becoming better than ebay these days. I sometimes forget it exists though.

 

[Kelpie]

What I mean is if its on the wire I cannot adjust the panels to the sun

Mine hangs on the top wire only. I can adjust it from completely vertical (like a dodger) through horizontal (like a wing) and to some extent past vertical if I'm trying to catch the sun on the other side of the boat. That last option leaves it vulnerable to the wind flipping it right round, though.
The adjustments are all made by pulling on bits of string. You will not find a cheaper or simpler way of mounting a solar panel than this.

 

[zoidberg]

The OP's problem is much the same as that faced by French 'Figaro-Solitaire' racers. Many of these mount one or sometimes two panels on 'single-point' supports made from a modified sailboard flexible mast base/joint onto the corners of a small tubular pulpit.. That supports the panel. The angle is controlled by cords from each corner, adjusted by rolling hitches or Clamcleat Aero devices.

The system(s) work. All the way across the Atlantic to Guadeloupe.

 

[DangerousPirate]

Mine hangs on the top wire only. I can adjust it from completely vertical (like a dodger) through horizontal (like a wing) and to some extent past vertical if I'm trying to catch the sun on the other side of the boat. That last option leaves it vulnerable to the wind flipping it right round, though.
The adjustments are all made by pulling on bits of string. You will not find a cheaper or simpler way of mounting a solar panel than this.

The OP's problem is much the same as that faced by French 'Figaro-Solitaire' racers. Many of these mount one or sometimes two panels on 'single-point' supports made from a modified sailboard flexible mast base/joint onto the corners of a small tubular pulpit.. That supports the panel. The angle is controlled by cords from each corner, adjusted by rolling hitches or Clamcleat Aero devices.

The system(s) work. All the way across the Atlantic to Guadeloupe.

You two have any pics so I can imagine that better?

 

[jdc]

Fridge is about 5.5A when running, which is obviously not 100% of the time. Voltage is 12.7 (more if the engine is running or the batteries are charging). 24 hours in a day. So WattHours a day is 5.5 X 12.7 x 24 x duty cycle, =1676 * duty cycle.

50% would make it 838, so 1000 is probably an exaggeration, but it's still loads compared to anything else. So this is where one should, imho, spend money for greater efficiency or better insulation (or a smaller fridge!).

 

[DangerousPirate]

Okay.