Solar Energy for Fan.
Better if The Battery has about 100Ah (many hours with that Load-Fan). Settings : 13.5V is MAXIMUM for a 12V normal Car-Battery; (if higher : The Battery will "boil", in time). NEW POWER INVERTER with 2N3773 and Toroidal Transformer ; only with heat-sinkers = NO NOISE !!!
Better if The Battery has about 100Ah (many hours with that Load-Fan). Settings : 13.5V is MAXIMUM for a 12V normal Car-Battery; (if higher : The Battery will "boil", in time). NEW POWER INVERTER with 2N3773 and Toroidal Transformer ; only with heat-sinkers = NO NOISE !!!