A method and apparatus use a programmable logic circuit to receive data representing environmental conditions such as irradiance, temperature, wind, snow, elevation, and the like, in a given location, to provide an input signal to a simulated variable power source which produces an output that approximates the output of a variable power source such as a photovoltaic panel that is subject to such environmental conditions. Power from the simulated variable power source is separately directed to each of a number of power converters and the efficiency of each power converter is tested to determine the optimum power converter for use with the variable power source in the given location.