[Bjorn to farm.]

I know what you mean by resting in the middle but the shade it throws is an irritant.
I’ve been racking my brain trying to find a simple solution to get it down the far side.
There is a company that makes roll-up tarps for grain trailers. They have some good ideas.
Yes, please PM me the wiring diagram. I love shit like that.

[Bjorn to farm.]

https://www.michels.ca/product/grain...product_2.html

[TychoMonolyth]

I would think any garage door company would have something for you. I saw a roll up tarp being installed on a steel machine shed door last summer.

[CrushnYuba]

It doesn't really block any light iff installed well. Luckily, you are doing a very short greenhouse and it will be a breez to get dialed.* When it's all rolled up,* that strip down the middle will be about 6".* The clear plastic cover diffuses light and sends light in different directions.

To make a 10ft wide hoop, it takes a 20ft wide piece of clear plastic.* 6" of that will be blocked by the blackout bars when it's all rolled up and it's mounted at the highest point in the house. Doesnt matter what position the sun is, there shouldn't be a shadow casted on any part of your plant canopy at any time of day.

I have used a system just like the link you posted. A cable spool attached to the roller to pull the bar as it unrolls when you don't have gravity to pull it. I don't think it would work for up and over. It really just to move the bar horizontally. I used it to unroll an insulating blanket.

[Bjorn to farm.]

What do you consider short?

[CrushnYuba]

Maybe you didn't say what size you were doing and i confused it with another post.

The longer the greenhouse, the harder it is to connect the bar to all that plastic evenly. Anything under 40ft long is very easy. 60 ft is a little harder. Closer to 100ft takes a couple sets off hands and a bunch of rolling up and down to see if you got it right. The straighter it rolls, the closer you can get the bars rolled to the center.

The wider and taller the greenhouse is, the wider the strip can be down the middle blocking sun without it casting a shadow. It's all about that diffused light from the clear plastic that makes little things up high not cast shadows.