A method of maintaining the temperature of a solar heating panel with glazing below about 220.degree. C. utilizes convention cooling, where it is essential to the success of the method that the glazing be at least two inches above the upper surface of the collector. A panel of unitary construction of essentially the same plastic material which is an embodiment of the method can withstand the normal operating conditions to which such panels are subjected without thermal degradation of the plastic nor danger of rupture attending loss of physical integrity at excessive temperatures.