NOVELTY - A solar water heater composite material comprises polypropylene oxide ether polyalcohol with degree of functionality of 6, polypropylene oxide ether polyalcohol with degree of functionality as 4, phthalic anhydride polyester polyol with degree of functionality as 2, castor oil polyol with degree of functionality as 3, foam stabilizer, deionized water, n-pentane as foaming agent, tert. amine catalyst, and polymethylene polyphenyl polyisocyanate.    USE - A solar water heater composite material.    ADVANTAGE - The composite material is capable of retaining the appearance of the water tank of the solar water heater well. It has no case in which the inner container is not collapsed at the same time. The water tank is not unshelled. The foam is not cracked in low-temperature environment at - 35 degrees C. The foam surface of the vacuum pipe is smooth without cavity. The heat conductivity factor is low. The insulation property is excellent. The composite material is environment-friendly.    DETAILED DESCRIPTION - A solar water heater composite material comprises component A and component B. The component A comprises (wt.%) polyether polyol A (42-46), polyether polyol B (26-30), polyester polyol C (3-5), biopolyol D (3-5), foam stabilizer (1.2-2), deionized water (1.2-1.6), foaming agent (14-18), and tert. amine catalyst (0.5-2). The polyether polyol A is polypropylene oxide ether polyalcohol with degree of functionality of 6 and molecular weight of 800-1000. The polyether polyol B is polypropylene oxide ether polyalcohol with degree of functionality as 4 and molecular weight of 500-700. The polyester polyol C is phthalic anhydride polyester polyol with degree of functionality as 2 and molecular weight of 300-400. The biopolyol D is castor oil polyol with degree of functionality as 3 and molecular weight of 800-1000. The foam stabilizer is SI-C surfactant B-8525. The foaming agent is n-pentane. The component B is polymethylene polyphenyl polyisocyanate. An INDEPENDENT CLAIM is included for a method for preparation of a solar water heater composite material comprising preparing material of component A, adding weighed polyether polyol, polyester polyol, and biopolyol D into reaction kettle to stir, adding catalyst, foaming agent, water and foam stabilizer, reacting, stirring for 2-3 hours, and mixing the component A and the component B at a weight ratio of 100:100-105.