Large solar array support beams

[Lee Jerry]

Originally Posted by s/v Jedi

For the 8020 website the calculator is here: https://8020.net/deflection-calculator

I checked for a single metric 4080 standard profile and got about 1.5” deflection.

A strut would fix that and they have nice variable angle fittings to connect the strut to the beam, but I see no good fittings to fasten beam and strut to the stainless steel tubes of the arch.

What inputs did you use to get that? I can't replicate it. For 12.5kg load, I get 0.2" for 1.5m length and 0.6" for 2m length.

[s/v Jedi]

Originally Posted by Lee Jerry

What inputs did you use to get that? I can't replicate it. For 12.5kg load, I get 0.2" for 1.5m length and 0.6" for 2m length.

Not sure what I used, but I just tried again:

[Lee Jerry]

Originally Posted by s/v Jedi

Not sure what I used, but I just tried again:

That one I can match.

However, there is something odd (wrong?) going on with that calculator. For example, When I double the load, it doesn't give anywhere near double the deflection (gives around 30%, it should be exactly double). And when I put in a load of 0.01kg it still gives 0.29" of deflection, should be very near 0. May want to look for a different one.

[s/v Jedi]

Very surprised that this lamination, 0.72 mm thick skins around foam core which is at its thickest point maybe 2” but much thinner for most of it.

Supported at both ends (1.5 meter apart?) it took 1,200kg to break it.

The skins were formed from 3x 210g regular weave plus an 88g finish skin, so total 718g which translates to 0.718mm layup thickness. The projected strength for regular weave carbon fiber is 600psi and we have to assume the skin on one side broke before the other side did so let’s estimate the too of the wing to be 12” wide…. 12 x 0.718 = 8.6mm high at an inch wide. 25.4 / 8.6 = 3 so the projected strength is a third of 600 pounds = 200 pounds or 100kg.

So the other 1,100kg of strength was all due to the core and the skin on the other side. The compression strength is a bit less, 570psi so the skin in compression must have failed first?

More important is the deflection. At 100kg there was only a 6mm deflection while the single skin would have bent like a rubberband.

I am finishing my “accurate measurements” which are still guesses as I am at the other side of the world from Jedi right now, but they will be very close because I have data from the previous array and it’s frame. I am drawing some diagrams now and will post soon.

https://www.youtube.com/watch?v=FFi2H_PC7hw

[s/v Jedi]

Here is another picture I made during the construction of the frame for the previous array. It shows the tubing of the arch as well as the moving arm for lifting the dinghy, which plays a role for the supporting strut.

The arch has a beam in front and back. The back beam is the strong one and is doubled with a web of small struts connecting them.

The two upper tubes are 1.5” diameter and the supporting tube as well as the interconnecting struts are 1.25” diameter.

For this frame, the strut was done from the upper tube because I couldn’t not source fittings for the smaller tube. In order to get an angle for the strut, I put the frame on vertical legs to raise it 6”.

For horizontal for-and-aft pipe of the frame is about 90cm. The panels on top were sticking out forward about 5cm and aft about 75cm for a total length of 170cm.

The new cassettes need support at the very end of the panels because of the sliding mechanism and those panels are much longer: 209.5cm. The cassettes can stick out a bit, but side wall and sliders add another 4cm at each end, for a total length of 217.5cm. I think the supporting beam should be 210cm long with the cassette sticking out less than 4cm each end.

I can lower the hinge point for the dinghy lift arm about 10cm, but I would prefer to also make that arm 10cm longer, so I want the beam and support strut to work for the current position with the dinghy hoisted up fully. The dinghy lift arm comes up to the same height as the lower tube, but the too of the arm is bent out so there is horizontal distance of about 30cm. The strut must clear this.

So, considering all the above, the beams will be 210cm long. Starting from the inboard end, we have the following attachments:

- at 10 cm the first 1.5” diameter arch tube.

- at 50 cm the second 1.5” diameter arch tube, with 15cm below that another 1.25” arch tube which can connect the strut.

- at 100cm the strut to beam attachment. As the beam and strut will be one continuous part, it may extend much further, but for the simplified diagram for calculating strength, this is what I plan to ise.

- beyond the strut a 110cm span, which would become the cantilevered beam.

I am thinking to make the beam core 10cm high above the arch tubes and I haven’t decided on the width yet. A 5cm width foam core feels right and allow good lashing to the arch tubes and cassette.

Lee Jerry made a good observation about the weight distribution with the sliding panel deployed. I had thought to put the beams about 75cm apart and let the cassette overhang 25cm at the inboard end to counter that shift of weight during deployment of the sliding panel, but I want a single beam able to support the full weight of the cassette just to make it strong enough to my liking.

Have you seen the frame of the solar array of the guy at the Young Barnacles YouTube channel? It’s tiny carbon fiber tubes! He’s an engineer so I bet it’s strong enough but it doesn’t feel right.

Now here comes my problem. With the support strut almost reaching halfway down the beam, it would carry the full weight if it was long enough to life the beam off the upper arch tube. I think I want to distribute the load.
Besides making patterns for each beam to deal with variations of the arch tubing, how can I fine tune this so that the beams sit in the same plane and the load gets distributed?

With the previous frame, the fittings I used were for tubing with an 1.67” O.D. and I used a deck anti-skid tape around the tubing to make it a tight fit. I guess I can do something similar for fine tuning these beams, using a tape that doesn’t compress, like UHMW tape?

[eMarineSystems]

Jedi,

There is a company in East Haven CT that specializes in G10 and carbon sheets and tubes.

https://currentcomposites.com/

Marc

[Bluechart]

We have a simple, but effective solar setup, which allows articulating panels.
I move the panels a few times a day, keeping them as perpendicular to the sun as possible.
At night I try to anticipate where the panels should be set for sunrise, so charging begins as soon as the sun rises…

The frame is made up of 4 pieces of “L” shaped channels, and solar panels, that rotate on a bolt, and are held in place with a knurled knob.

When it’s expected to be windy, or when leaving the boat, I tighten the pivot bolt with the panels in a horizontal position.

Some pics here
https://sailsoiree.smugmug.com/Boats...d-Solar-Panel/

[Noahr]

Check out this YouTube example for ideas on sliding panels:
https://youtu.be/F27yfLGhazE

[Dirk01]

Originally Posted by s/v Jedi

I am designing cassettes that hold two large solar panels (think 2 x 1 meter panels) with one panel fixed on top and one sliding panel below. These would come to around 50kg weight so a hefty cassette.

...

Hi Nick,
I'll try to put it into words. Hopefully you can follow me, because English is not my native language.

Well, my plans are pretty similar to yours. But my plan is to carry 3 solar panels. The orientation is perpendicular to the direction of travel (like the dinghy). However, they will be a bit smaller. The added up power is "only" about 1kWp electric power and a little less thermal power (yes, you read right ;-) ).
The arch shall support a combined electrical/thermal panel (let's call it E/T panel) in the center and directly above the dinghy storage. Two slightly smaller panels are directly below the E/T panel and are supposed to extend out the side when not in motion or when the wind and seas are very calm and during daylight hours. How I connect the panels to the SS tubes of the arch, and how I fit them perfectly into the arch itself at their end positions is not yet clear. But I'm sure I'll find a simple and bulletproof way. The panels are not only to provide power, but also shade. Since the panels reach up to the sugar scoops, the arch needs to be high enough so that you don't accidentally bump your head.
The arch may have a second important function as a crane. Although I will have davids to hang the dinghy from, I plan to put the dinghy on the davids as well in certain situations (underway, likely unsafe spots, ...). In this regard, it is much easier to implement theft-proof storage or to have it far away from high seas underway. However, the details of how I can most easily get the dinghy onto the Davids are not yet clear. There are several conceivable solutions.
Because of the many things that can shade the panels, I opted for the hot spot free panels. Although they are less efficient, I think I can get more work out of them at the end of the day.
I'm going to add a few more smaller panels to the roof and maybe attach them to the railing in a theft-proof way when I'm at anchor.
Maybe I could give you an idea? See attachment ...
Cheers
Dirk

[Dirk01]

Originally Posted by Dirk01

Hi Nick,
I'll try to put it into words. Hopefully you can follow me, because English is not my native language....

Sorry Nick,

a Sundeer 64 is a very nice looking monohull. Well, my choice I'm talking about is a catamaran. Makes such things much much easier.

Chhers
Dirk

[Painless]

Have You seen the solar rack Matt made on “Sailing Athena”? (YouTube) He has two panels active at sea and four at anchor. The two lower panels slide out when they are not sailing.

[s/v Jedi]

I checked Mads his setup again. He simply installed 2 meter long rails to slide out a 1 meter wide panel, which is easy when you have two fixed panels in the center, giving you the two meters for that.

I much prefer the cassettes with full extension slides that fit inside the cassette. I must admit that there are several reasons I didn’t mention yet: I can fit two more of those cassettes elsewhere during a later project. (8x 440W total )

Also, I want to be able to quickly throw different panels into the cassettes, with different dimensions, without much alterations.

I have been looking at a solar hot water collector until I got crosseyed from it, but I simply have no good path for the boiler fluid circulation lines. I now plan to switch our electric water heater on automatically based in the battery SOC and there being solar generated power available. I have a 750W element in it.

[s/v Jedi]

Originally Posted by Dirk01

Sorry Nick,

a Sundeer 64 is a very nice looking monohull. Well, my choice I'm talking about is a catamaran. Makes such things much much easier.

Chhers
Dirk

It sure does, but I have a feeling the cassettes I’m designing are gonna find their way on catamarans too. The world is changing quickly and having plenty solar power may play a big role on future cruising boats

I still wouldn’t trade Jedi for a cat… not even a 60’ Gunboat

[RaymondR]

Originally Posted by Painless

Have You seen the solar rack Matt made on “Sailing Athena”? (YouTube) He has two panels active at sea and four at anchor. The two lower panels slide out when they are not sailing.

For my last capacity expansion I hinged a panel on each side of the bimini so that I can fold them up vertically if I need them to be within the hull's beam.

[Dirk01]

Originally Posted by s/v Jedi

...
I have been looking at a solar hot water collector until I got crosseyed from it, but I simply have no good path for the boiler fluid circulation lines. I now plan to switch our electric water heater on automatically based in the battery SOC and there being solar generated power available. I have a 750W element in it.

Okay,

then my idea about the combined electric/thermal power panel isn't anything making sense for you. Maybe it makes sense for others...
TBO, I don't know yet enough about temperatures and effort to get the heat from the panel into my hot water tank and how big it should be to get out enough warm water for two short showers a day and the typical dish washing of course..

However, I wouldn't change to a gunboat 60ish also. Not because I don't like it or I wouldn't have the money to run it (which I defintively have not), but for only 2 people it's just overkill

Cheers