Solar panel

A process for heating water in a swimming pool, or the like, comprising:

• (a) dimpling at least one of at least two corrugated heat retention surfaces at a depth between about 1/4 inch and 1/2 inch;
• (b) mating said heat retention surfaces;
• said mated surfaces being retained at a distance from each other depending on the depth of said dimpling step (a);
• (c) orificing one end of said mated surfaces of step (b) to control the flow of water between said mated surfaces of step (b);
• (d) installing at least one pair of said mated surfaces of step (c) on a means for exposing said mated surfaces to the sun in proximity to the swimming pool, or the like;
• (e) pumping water from the swimming pool, or the like, to the orificed end of said mated surfaces of step (d);
• (f) flowing the water of step (e) through said mated surfaces of step (e) toward an outlet therein at a rate of between about 10 lbs./sq. ft. of mated heat retention surface/min. and about 200 lbs./sq. ft. of mated heat retention surface/min. such as to form a water film exposed to the sun, said flow rate being determined by said orificing step (c);
• (g) absorbing into said flowing water film of step (f) between about 1250 BTU's/day/sq. ft. of mated heat retention surface and 2500 BTU's/day/sq. ft. of mated heat retention surface;
• and
• (h) returning said BTU absorbed water of step (g) from said outlet to said swimming pool, or the like.