Accurate measurement and estimation of solar cell temperature in photovoltaic module operating in real environmental conditions

There is a growing need for the precise outdoor performance measurement of photovoltaic (PV) modules for low-cost onsite performance measurement, monitoring, and failure diagnosis. For the precise evaluation of a PV module, an accurate temperature measurement technique is required. It is necessary to measure the temperature of the solar cell in a module structure (junction temperature) because it determines the temperature characteristics of the PV module, rather than the temperature of the backsheet. In this study, a PV module with an internal thermocouple was fabricated. A thermocouple was inserted immediately below the solar cell so that it could be in direct contact with the cell, enabling an accurate temperature measurement. Moreover, the temperature of the solar cell in the PV module structure was predicted by heat flux calculation using the backsheet temperature, which can be measured easily. In this manner, the solar cell temperature was estimated accurately within an error of +/- 1 degrees C. (C) 2018 The Japan Society of Applied Physics