Contents lists available at ScienceDirect Sustainable Energy Technologies and Assessments journal homepage: www.elsevier.com/locate/seta A new approach for photovoltaic module cooling technique evaluation and comparison using the temperature dependent photovoltaic power ratio Sakhr M. Sultan ⁎ , C.P. Tso, M.N. Ervina Efzan Faculty of Engineering and Technology, Multimedia University (MMU), Jalan Ayer Keroh Lama, 75450 Melaka, Malaysia ARTICLE INFO Keywords: Photovoltaic module Cooling techniques Evaluation Comparison Photovoltaic efficiency Photovoltaic power ratio ABSTRACT Many photovoltaic module cooling techniques are available to reduce the solar cell temperature, resulting in enhanced efficiency. Although the power of the photovoltaic module is usually reported as a measure for the performance of the cooling technique, the performance assessment and comparison among different coolers become difficult if different photovoltaic module’s reference power is being utilized. The existing method re- quires calculations to be done repeatedly to obtain the photovoltaic module’s power, for any given value of the reference power. In order to compare the performance of the coolers, the use of the same reference power is needed, resulting in a lengthy process. Hence, a new assessment method is proposed, based on the temperature dependent photovoltaic module’s power ratio that is defined and derived. The new method identifies the re- levant parameters that are essential for measuring the performance of the cooler such as the power of a pho- tovoltaic module with a cooler and the reference power at photovoltaic module’s standard test conditions. The outcome is that the calculation of the unknown power for different reference power can be instantly obtained and the performance comparison among different coolers become simple without going through the lengthy process as it is in the case of the existing method. It is shown that the proposed method has the same results as the existing method which is experimentally validated. This is evidence to support the new method which may have potential to be applied by photovoltaic module cooling techniques designers. Introduction Photovoltaic effect directly converts solar radiation into electricity, and photovoltaic devices are rugged and simple in design requiring very little maintenance, yet able to provide a wide range of power outputs. They are used as power source, in remote buildings, solar home sys- tems, water pumping, communications, satellites and space vehicles, reverse osmosis plants, and in even mega-watt-scale power plants. With such a wide array of applications, the demand for photovoltaic devices is continuously increasing [1]. The performance of the photovoltaic module (PV) is defined by its corresponding I-V characteristic curve, which is the correlation be- tween the electrical current, I, from the PV, versus the voltage, V, across it, at a reference PV temperature and solar radiation of 25 °C and 1000 W/m 2 , respectively. Fig. 1 shows an example of I-V characteristic curve. Three points are available on the I-V characteristic curve which are: (i) the maximum power point, MPP, (ii) the open-circuit voltage, V oc , and (iii) the short-circuit current, I sc . The output power from a PV can be calculated using Eq. (1.1), = × P V I max MPP MPP (1.1) Normally, a PV is measured under standard test conditions (STC): 25 °C reference PV temperature and irradiance of 1000 W/m 2 under the standard AM1.5G or AM1.5D spectra. The values of the irradiance and spectrum are created in the 1970s and are meant to represent “typical” radiation incident on a surface tilted 37° with respect to a horizontal plane at mid-latitudes in the contiguous USA [3]. The selection of 25 °C is a matter of suitability: it allows indoor testing of PV near room temperature [4]. There is a negative impact on the PV efficiency, as a PV becomes hot during operation, cooling is desirable. Many PV cooling techniques are available in different modes which are natural or forced convection cooling [5–7]. Fig. 2 shows a PV with and without implementing a cooler. When a fluid flows under the PV’s surface, thermally induced convection occurs since the PV surface and the fluid are of different temperatures. The motion of the fluid improves the heat transfer on the PV surface (convection cooling). As a result, the PV performance can be improved. There is a considerable amount of studies conducted in current https://doi.org/10.1016/j.seta.2020.100705 Received 28 January 2020; Received in revised form 31 March 2020; Accepted 3 April 2020 ⁎ Corresponding author. E-mail address: mas2007_eng@yahoo.com (S.M. Sultan). Sustainable Energy Technologies and Assessments 39 (2020) 100705 2213-1388/ © 2020 Elsevier Ltd. All rights reserved. T