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Solar tracker

DrDoggy2

Member
I would like to mount some solar panels on my 4x6 trailer to extend and "pop-up" much like one of those popup trailers.
In my region I have googled that the ideal angle will be max at about 5 ft vertical. 57degrees
I and i would like it to drop to 0 ft when travelling(0ft vertical is at the pivot point, along the top of the trailer box).
And want it to tilt in any direction, so i can park trailer in any direction.
I plan on just using some 2x2 lumber for the frame of the mount.
I figure i will get 4-6 pannels on the mount.
I figure the pannels and mount will weigh around 100-200 lbs.
With limited mechanical supplies I figure it will be easiest to use 4 actuators in each corner of the trailer, using the diagram posted,
I figure that will be the easiest configuration. It doesnt seem stable to have it all sitting on a single bar in the center like most mounts i see.
The actuator i found with a low price and high stroke is:

so can i assume that each actuator will need to support 200/4 = 50lbs, plus the fulcrum adjustment(20" = 1.5ft) = 50lbs*(5/1.5) = 166LBS
I dont know if that last paragraph is correct or even made sends(probabally not)? or how to properly calculate? will the actuator posted be enough(900N)? should i use somthing other than 2x2 lumber for mount and arms? is there simpler config? ideas?
thanks!
 

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DrDoggy2

Member
Great Info,
Rain I'm not worried about since when we have rain it s pretty cloudy so I will just retract it to the 0 position when raining.
Wind is a problem here, so that is good idea i will put a wind guage on it to retract for the higher end winds.

So mine is only half the area as his, so does that mean I only need half the newtons (750N)?
Plus i am using 4 of them, for each corner.
In which case the actuator I picked is coincidently almost perfect?
 

Tony Stewart

Well-Known Member
Most Helpful Member
I've seen some massive pivoting PV anchors ripped apart from wind force. You would need 2" Nylon web anchors to prevent motion that might flip the van.

I use that just to tie down my canvas patio cover thru 2x4 struts to the patio from getting carried away with gusts on a windy day.

It is a sail with leverage that will fail in what you show.
 

DrDoggy2

Member
Here is another drawing of my intent.
The array will be flush, inside, the box when the veihicle is in motion.
I do get heavy winds, up to 100kph about 4x a year, I can do up a detector to have it receed in to the box aswell during these undesired conditions.

Is this sound? Where should i set my wind limit? Should/how to beef up?
 

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Tony Stewart

Well-Known Member
Most Helpful Member
I would compute or measure the force at some windspeed and factor that the drag will be proportional to v² and choose a 10yr 80% probability windspeed rather than 1yr 400% probability windspeed.
 

DrDoggy2

Member
so wind force max is 720N,
plus my wieght is actually closer to 100lbs, did i calculate the fulcrum corectly above? [100lbs * (5ft/1.5ft)] = force on arm = 333lbs = 1666 Newtons?

is that right? can i divide that by 4 since I am using 4 actuators or does that value apply to each, since weight is distributed to the bottom corners when sloped?
 

Tony Stewart

Well-Known Member
Most Helpful Member
The fulcrum divides the displacement and multiplies the force on the actuators.
Turbulence can amplify forces greatly.

Keep searching for better designs and force calculators, http://lumber.soundcedar.com/calcul...sure]=D&calc[height]=0&submit=Calculate+Force

- consider forces on all latches and twisting members. and use at least a 3 to 6:1 safety factor.

- Examine the trailers with Changeable Message Signs (CMS) for tubular steel construction as a minimum.
- the glass may be brittle , so stress- strain reinforcement may b more important than force retention of actuators.

Your concepts so far are far too under-designed.
 

Tony Stewart

Well-Known Member
Most Helpful Member
Structural resonance excited by wind turbulence can also amplify stress-strain beyond the breaking point. Most structures have a gain or Q of at least 10 at some frequency, so this is made stiff to raise the f and lower the x displacement.
 

Dr_Doggy

Well-Known Member
unfortunately , I dont have the gear to steel work, nor any idea where to get supplies. besides I have made similar wooden shelves that support larger weights so im sure some 2x3 or 2x4 lumber will suffice? It all comes down to the actuator requirements. It is only 24sqft and an extra 3ft on the trailer height.

also the calc posted says exposure b is 1,637.714 N-m, and exposure d is 730.491 N-m
.... but if exposure b is with buildings and obstructions and exposure d is "most severe exposure that is flat and unobstructed"
.... then shouldnt those values be reversed ?
 

Dr_Doggy

Well-Known Member
ok, i now see the errors in my ways, so I have found a new design where i can fix my 2x4's in to a secure vertical position and have more secure latches, but this new plan will require stepper motors.

But i run in to the problem again where I need to know the torque of the motor required.
I will need to find a stepper motor and a "bobbin" to go on it that is able to wrap up 5ft of the wire. I think the wire i have is ½" thick. But idk what the bobbin is called!
also a larger ID means more torque correct?
so off hand i found a stepper that is 48oz*in, so a 10" bobbin maxes out at 480oz, is that correct?
 

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