Cooling and heating the greenhouse is important, but differs depending on what part of the country you live in. The northern climates need to have well insulated greenhouses. The southern climates need to think about cooling. Swamp coolers are often used and also shade cloths. Of course ventilation is important in any location.
Different plants require different amounts of light.
Find out what the individual plant needs and locate it in the best part of the greenhouse for that plant. Some plants love the shade and others need maximum light. A solar greenhouse will receive more light than the others. That is the whole purpose of them. It will save on the heating bill.