Here is my sperimental solar panel that heats both air and water, also provides a few hundred watts of electricity for small electrical utilities, follow the link for more details.
Experimental panel that heats the air in the house and preheats the water from the solar thermal panel (solar circuit, not the sanitary one) to increase its efficiency in winter.
The solar panel is 2.5 meters by one meter by 20 cm, made with a polyurethane insulated sheet metal panel, front and sides in honeycomb polycarbonate; it is exposed to the south and inclined vertically, to optimize production in the cold season and not overheat in the summer.
The copper water pipe must have a strictly uphill slope for the entire route to avoid air pockets that would block the natural heat flow.
The hot surface of the corrugated sheet metal increases, increasing efficiency, the matt black paint is of the type for high temperatures (800 degrees centigrade), an economical but valid solution.
There is a 15cm diameter air inlet at the bottom with the 36W fan that takes air from the outside filtered with plastic fabric, like the one used in kitchen hood filters.
A T-connection pipe has been placed in the outlet with a mobile circular bulkhead inside to switch from winter to summer mode; in summer the heat is thrown out in a controlled way to avoid overheating of the panel; the PVC outlet pipe has been internally lined with high temperature polyamide Kapton tape, to avoid fumes.
The electric solar panel is 100W, the battery is 12V 130Ah, the fan is 35W at 220V. The control panel contains the charging module, the module for measuring the energy produced by the panel, the thermostat for the hot air, the 12V to 220V inverter for the fan, the thermostat to block the gas boiler if there is sufficient hot water.
