Ingenious solution shown on the site solar.freeonplate.com/en/ served as inspiration to build "home-made" efficient solar collector.Basically, it is simple solar panel for supplemental home heating, which heats the air directly.The collector is almost entirely constructed out of empty aluminum cans!Housing for solar collector is made of wood (plywood 15mm), while its front is 3 mm (0.12 inches) Plexiglas/polycarbonate (you can use tempered glass as well). The back of the case set is made of 20mm rock wool (or styrodur) as insulation.Solar absorber is made out of beer and soda cans, painted in matte-black paint resistant to high temperature. The upper part (cover) of cans is specifically designed to provide greater efficiency in heat exchange between the cans and the passing air.When it is sunny, regardless of outside temperature, cans and inside air heat up very quickly. The fan drives heated air back into the room.To begin with we have collected empty cans from which we will assemble solar panels. We have marked three holes on each can with nail, then drilled the bottom. Carefully cut the top of the cans in the form of star, and then distort free parts using pliers. Remove grease and dirt from the surface of cans. Glue all cans using any adhesive silicone resistant to high temperatures. A series of glued cans form a solar tube.Boxes of intake and exhaust parts are made of wood or aluminum. The box are drilled, cut-outs are 55mm in diameter. The first row of cans is glued to the cover of the suction boxes.Solar absorber fit in the casing made of wood. Back of the box solar collector is made of the plywood. At the end, the solar absorber is painted in black and placed in the case. The casing is covered with plexiglass that we attach to the frame and thoroughly complained silicone. Polycarbonate / plexiglass is slightly convex in order to gain greater strength.After completing installation of collector, the outside temperature was -3 ?° C, and from the solar collector is coming out 3 m3/min (3 cubic meters per minute) of heated air. Heated air temperature went up to +72 ?° C. Calculated power that the solar panel produced, was approximately 1950 W (watts) which is almost 3 HP (3 horsepower)!!!