Passive solar roof slope

I am building a passive solar greenhouse and need advice with roof slope. All of the calculators I find use the winter solar elevation at my latitude. However, I want to shut the greenhouse down for the year at the end of Oct and capitalize on an early spring. Our solar elevation is at about 30 degrees on April 1. Can anyone provide a resource to determine roof slope for this elevation? This may be really simple, but it’s a roadblock in my brain.  Thanks!

My understanding is that you want to have your glasing perpendicular to the angle of light for best use of the light.

If you wanted to make sure you got the very best sun and heat on April first then I would design it so that the collection area is at a 60 degree opposing angle.

The good news from what I've read is that you will get good energy penetration at up to 45 degrees away from perpendicular.

By aiming your collection angle toward the sun at this date it would seem to me that it does not take advantage of the thermal battery of your back wall in a passive design.
I also think it would take a great deal more complex math to find out where your insulation should start and glasing stop should you wish to avoid over heating the greenhouse in the summer.

The simple math is usually your latitude plus 20-38 degrees. This will roughly give you the answer you need for winter solstice positioning. Most designs are made to acommodate for the best temps year round.
I would stick to that but i would also lobe to hear some more intelligent permies give you the answer to the awesome and interesting question of how would one design to optimize spring only use!

I hope this was helpful and I hope even more that a passive design guru comes along and enlightens us both!

Best of luck!