Here's my favorite type of greenhouse, the geodesic dome - Greenhouse kits, Geodesic Dome Greenhouse, Greenhouses SUPER energy efficient and you could grow all year round. Expensive, but you could also do DIY and sites on the web can show you.
I built my geodesic dome greenhouse with a rough 3V configuration. It is very effective and efficient. The hardest part was building the wrapping film around rather than the frame. Originally it only had a ventilation top and a side door, with time I've added a solar panel feeding a temperature control timer opening the vents as required.