An accelerated weathering test apparatus of the type used to concentrate
solar radiation upon test specimens including a heating element that
transfers energy to the test specimens. A temperature sensor is
operatively coupled to one of the test specimens for generating a test
signal representative of the operating temperature of the test specimens.
A controller for generating a temperature set point is connected to the
temperature sensor and responsive to the test signal for selectively
controlling a power level applied to the heating element in order to
control a rate at which energy is transferred to the test specimens.