Looks like a duct-mount fan. If it's mounted on a wall panel, you'd be better off with something like this:
It should be mounted on the side of your greenhouse that's shaded in the afternoon, close to the ground.
At 8000 ft. we have strong summer sun. I use shadecloth and passive venting, with thermal pistons on louver vents at the corners and clerestory roof vents, also driven by thermal pistons.
