Many solar greenhouse designers recommend using a roof angle that is perpendicular to the angle of the sun in the winter. While this does indeed maximize light transmission in the winter, the effect of a lower angle is not severe. We explain this relationship much further in our blog, Choosing the Best Roof Angle for your Greenhouse. Furthermore, there are a few logistical challenges to creating very steep pitch — you cannot use glass view windows on the south; it can reduce headroom or create an awkwardly tall greenhouse. Due to these pros and cons, most of our residential growers are built with a shallow angle roof. If you have a need for a steeply pitched roof, just ask us.