A method for operating a power-compensated fusion furnace that includes a power control system having one switching device per heating element, power measurement circuitry, a master temperature sensor, and a controller. Each switching device is electrically connected to a respective heating element. The controller, in conjunction with the switching devices, is able to individually control the electrical energy flowing to each heating element, thereby controlling the duty cycle of each heating element. The duty cycles are corrected for one or more of variations in the electrical resistance of each heating element and position-dependent variations in furnace cavity temperature.