Abstract: A method of increasing capacity of an air-cooled power generator 30 includes retrofitting a water evaporative cooler 48 to the generator. The water evaporative cooler 48 includes a water absorbent media 50, a controllable water inlet 52,53 for controllably delivering water from a water supply to the water absorbent media, at least one sensor 54, and a controller 56 responsive to the at least one sensor. The retrofitting includes mounting the water evaporative cooler 48 so that the water absorbent media 50 is in fluid communication a flow of cooling air, connecting the controllable water inlet 52,53 to the water supply, mounting the at least one sensor 54 for sensing at least one parameter relating to the flow of cooling air, and connecting the controller 56 to the at least one sensor to thereby operate the controllable water inlet based upon the at least one sensor.