posted 7 years ago
In your case, I think outside would be best.
Evacuated tubes aren't effected by cold weather as much as most solar thermal collectors and in your case it doesn't even get very cold.
Depending on the type of glazing used in your greenhouse, the amount of visible light blocked can be quite high, around 10% for glass and 20-30% or more for plastic.
And that is visible light, IR blocking is even higher.
My opinions are barely worth the paper they are written on here, but hopefully they can spark some new ideas, or at least a different train of thought