In cold environments, flat plate solar collectors are of limited value because high heat losses lead to low efficiency. The integration of polymethyl methacrylate (PMMA) sheet into flat plate collector is presented in this paper. The performance of this collector in cold weather was investigated using a three-dimension simulation model. A simplified experiment was conducted to verify the precision of numerical model and the simulation data can agree very well with practical ones. The effects of the thickness and location for PMMA sheet on the performance of collector efficiency following steady state were analyzed. The transmittance of transparent insulation material is the key parameter to achieve high performance for the collector. The optimum thickness of the transparent insulation material is 1 mm in simulated conditions and the best location of PMMA sheet was achieved. The result shows that the increase of the collector efficiency from the conventional collector is 11.3%, when reduced temperature difference is equal to 0.1 m(2 )degrees C/W and the ambient temperature is -20 degrees C. (C) 2019 Elsevier Ltd. All rights reserved.