Qingzhou Changrong Greenhouse Engineering Co., Ltd. produces solar greenhouses, specifically a one-vertical-one-slanted solar greenhouse. Solar greenhouses are only suitable for use in the northern regions. 

A solar greenhouse has a structure with one earthen wall, combined with wood and a film cover. The slanted side allows for better sunlight collection, and at night, the earthen wall can release the heat absorbed during the day. Solar greenhouses are low in cost.