A solar energy greenhouse includes a main structure, a roof structure disposed on the main structure and a plurality of thin-film solar cell assemblies which are disposed on the roof structure in an unequal gap defined there between. The thin-film solar cell assemblies can absorb sunlight and generate electrical energy. The unequal gaps between the thin-film solar cell assemblies are determined from the radiation angle of the sunlight and the position of plants in the solar energy greenhouse, so the amount that the sunlight radiates on the thin-film solar cell assemblies and the plants can achieve a better distribution, which improves the amount of electrical energy generated by the thin-film solar cell assemblies and the rates of growth of the plants.