Infrared thermographic analysis has been applied to the study of the thermal performance of in-situ solar collectors. It is shown to be especially effective for detecting poor thermal contact between the absorber plate and the risers, flow blockage in risers, and zones of enhanced heat loss. It also has excellent potential for use in solar collector production quality control and design. Thermograms of solar collector in-situ with glazings intact were shown to provide reasonably accurate but somewhat attenuated descriptions of temperature distributions on the absorber plate surface. Preliminary experiments were performed to enable the attribution of various nuances observed in the thermograms to physical defects in the solar collector.