Evaluating DC Voltage Temperature Coefficient of a Multicrystalline Module in Actual Environmental Conditions of Western Rajasthan, India

Abstract

Solar irradiance and cell temperature are the two most important parameters governing the efficiency of PV power plant. This paper presents simultaneous impact of cell temperature and the irradiance falling on the plane of solar panels-POA (Plane of Array Irradiance) on the dc voltage(V dc ) of a multicrystalline Photovoltaic(PV) module, one of the most important parameter governing dc power and hence efficiency of (PV) power plant. In contrast to existing literature which specify negative temperature coefficient for o C to 60 o C but as soon as sun begins to descent, cell temperature starts reducing and V dc starts increasing, maintaining nearly constant value in the range of 80-85% of its maximum rated value for about 6-8 hours. If cell temperature is less than about 45 o C, neither V dc reaches point of saturation nor does it attain constant value. Thus, high cell temperature has overall positive effect on dc voltage of a multicrystalline grid connected PV power plant. Western Rajasthan being blessed with high temperature and high insolation for 6-7 hours in a day for about eight months has the capability of high energy yield as dc power is directly proportional to dc voltage.

The Defining Positive Role of High Cell Temperature on the Performance of a Multicrystalline Solar Photovoltaic Module

“…Garg, JB showed positive effect of ambient and cell temperature on dc voltage up to 38 o C and 50 o C respectively [20]. In another paper [21] Garg, JB showed significant positive effect of cell temperature in 49 o C to 62 o C range and that V dc attains nearly constant and high value only at high cell temperature. Garg, JB also showed that significant dc power is obtained only at high cell temperature [22].…”

Unfolding Extraordinary Positive Effect of High Temperature and High Irradiance on DC Power Output of a Multicrystalline PV Module: A Case Study of Western Rajasthan

“…The results of Garg et al [5] also show that dc voltage decreases with increase in temperature only for ambient temperature greater than 38 o C and cell temperature greater than 50 o C. Garg et al [6] have shown that dc power output varies in direct proportion to irradiance outweighing the change in temperature. Power output at cell temperature 50-55 o C was far greater than power output at 40 o C. Garg and JB [7] have also shown that dc voltage attains a point of saturation maintaining nearly constant value in the range of 80-85% of its rated value for cell temperature greater than 49 o C. Mustapha et al [8] while evaluating the performance of a polycrystalline solar photovoltaic module under Maiduguri-Nigeria weather conditions have shown that current generated is directly proportional to solar irradiance and is almost independent of temperature. The maximum rated power was achieved during the sunniest month and module current increased by 0.1 A/ o C with increase in temperature, while module voltage decreased by 0.05 V/ o C leading to increase in power with increase in temperature.…”