Operating temperatures of open-rack installed photovoltaic inverters

• A method for modeling inverter temperature as a function of the operating conditions is proposed.
• A thermal model is demonstrated for predicting average inverter heat-sink temperatures.
• The three grid-connected inverters were tested to study heat dissipation factors in Colorado, US.
• The inverter components temperatures were measured and analyzed in Chang Zhou, China.

This paper presents a model for evaluating the heat-sink and component temperatures of open-rack installed photovoltaic inverters. These temperatures can be used for predicting inverter reliability. Inverter heat-sink temperatures were measured for inverters connected to three grid-connected PV (photovoltaic) test systems in Golden, Colorado, US. A model is proposed for calculating the inverter heat-sink temperature based on the ambient temperature, the ratio of the consumed power to the rated power of the inverter, and the measured wind speed. To verify and study this model, more than one year of inverter DC/AC power, irradiance, wind speed, and heat sink temperature rise data were collected and analyzed. The model is shown to be accurate in predicting average inverter temperatures, but will require further refinement for prediction of transient temperatures.