Some Studies on Performance Variation of A Laboratory Scale Solar Photovoltaic Pumping System on The Different Parameter; I.E. Module Surface Temperature; Solar Radiation; Pump Discharge Pressure in Different Seasons

Some Studies on Performance Variation of A Laboratory Scale Solar Photovoltaic Pumping System on The Different Parameter; I.E. Module Surface Temperature; Solar Radiation; Pump Discharge Pressure in Different Seasons

Ratan Mandal 1 and Subhadeep Chakraborty 2

1School of Energy Studies, Jadavpur University, Kolkata, West Bengal, India.

2Murshidabad College of Engineering and Technology, Bengetia, Berhampore, Murshidabad, West Bengal, India.

1Corresponding author

Abstract

Solar photovoltaic power may play a vital role for pumping water for drinking as well as irrigation purpose to the remote areas having no grid access. The efficiency or performance of a solar panel/module is dependent on various parameters, mostly on input solar radiation and temperature of the module. But, so far no work was reported on how the solar photovoltaic pump system efficiency changes with changing the temperature of the SPV module. In this paper we have used two similar laboratory scale SPV pumping system having solenoid type diaphragm pump, one with water spray mechanism for reducing module temperature and another with normal condition. The graphical representation of the result shows the variations of SPV pump system efficiency with different parameters i.e. module surface temperature; solar radiation; pump discharge pressure at different months of a year for both the systems. A noticeable module surface temperature variation (around 10C) was found. Sometimes that difference of temperature was reached at least 11C -19C. It is also found that the SPVPS1 system shows maximum system efficiency

(6.486%) at 1kg/cm2 discharge pressure in the month of March at the solar radiation of 615.143 W/m2 at 35C of its module temperature with maximum spv

panel efficiency (12.25%). While SPVPS2 system shows 5.288% system efficiency with 11.442% spv panel efficiency at the module temperature of 40C having the same other conditions. The variation of the efficiency was quite high at the other seasons for its quite large module temperature variation between both the systems.

1. Introduction

   Solar photovoltaic power may play a vital role to supply electrical energy to different electrical

   appliances and equipment. Standalone photovoltaic (SPV) systems are becoming increasingly viable and cost-effective candidates for providing electricity to remote areas. With the shortage of conventional resources SPV module takes a leading part to overcome forthcoming difficulties [1]. Irrigation system is such a system where abundant use of conventional energy is used. Now with the use of SPV pumping system with the higher efficiency the irrigation system become more eco-friendly [2]. The efficiency or performance of a solar panel/module is dependent on various parameters, mostly on input solar radiation and temperature of the module [3]. So, the reduction of temperature increases the solar module efficiency [4]. Therefore, solar pumping system efficiency or performances are also dependent on input solar radiation and temperature of the panel apart from its orientation and type of solar module and the pumping system [5,6,7]. The decrease of the solar radiation degrades performances (the global efficiency and the flow rate) of the PV pumping system. Also the maximum spv power and pump flow changes in the influence of temperature [8-9]. It is found that solar photovoltaic (spv) water pumping systems are particularly suitable for water supply in remote areas where no electricity supply is available as well as for the irrigation [10]. Also it is found that there is a very good match between the requirement of irrigation water and availability of the solar radiation. Whenever there is more requirement of irrigation, available solar radiation also be more and vice-versa [11]. Therefore, most of the spv irrigation systems are operated at the hot climatic conditions. Provisions of cooling arrangement of the spv panel/module may enhance the efficiency and the output performance of such systems. A lot of technique has been adopted for the cooling purpose of solar module [12]. In this paper normal water was used for cooling of SPV panel.

   The overall objective of this work was to determine how much system efficiency and performance can be improved by the present low cost method comparing with two laboratory scale similar systems: one solar module surface of solar water pumping system is cleaned and cooled and another is left normal condition. The water which is used for cooling, again used for irrigation system and keep temperature of that surface as cool as possible for the increase of the module efficiency. As module efficiency increase the discharge or flow rate is increased so, as a result we get more water for the irrigation. But in other case the surface of other module remains unaltered i.e. it is not cooled and cleaned by the spray of water in regular interval. So as a result free dust particle, which are in air continuously deposited on the module surface. As a result its panel efficiency is decreased and low amount of water is being discharged. The specific objective is summarized as below:

   1. To measure the solar radiation in regular interval, and observed the how the discharge (i.e. water flow) change with the radiation.

   2. To measure the electrical output in terms of (V×I) of associated PV modules.

   3. To determine system efficiency, Panel/module efficiency, and the panel/module temperature. And make a graphical representation for comparative study of both the system.

2. Experimental setup and procedure

1. Experimental setup

   Two similar SPV pumping systems have been taken to run the experiment successfully. The experimental system for the present work is located in the northern hemisphere in Kolkata (22°3410 N, 88°2210E). These systems consist of the following subsystem;

   1. Solar photovoltaic array (polycrystalline silicon solar cell), 2. Battery, 3. Battery charge controller,

      4. Water storage tank, 5. Solenoid type diaphragm pump, 6. Flow meter, 7. Pressure gauge, 8. Valve.

      The arrangement of the system is shown in fig.2.1 and fig.2.2.

      Fig.2.1 SPVPS1 Fig.2.1 SPVPS2

2. Experimental procedure

   In this experiment, the experimental procedure is same for the two systems [9, 11]. With the help of solar intensity meter taking the reading of solar radiation and it is kept along with the plane of the solar photovoltaic panel. It has the linear scale which gives the solar radiation in terms of w/m² units directly. A sample circuit has been made in each system to measure the parameters of the solar panel such as load current(IL), load voltage( VL), open circuit voltage(VOC) and short circuit current(ISC) etc. with help of multimeter for the both system separately. The load was diaphragm type solenoid pump unit which pumping water from the tank. The total load on the solar panel was changed by making the pump run and delivered water at three different discharge pressure (0, 0.5, 1 kg/cm2) the corresponding voltage, current values were recorded for future calculation. Of course it was for certain radiation

   levels which vary with the time to time in a particular day. Further the maximum pressure of the system at that particular radiation also recoded. The pressure applied (0 kg/cm2, 0.5 kg/cm2, 1 kg/cm2). For every pressure the discharge was recorded for five minutes. The readings were taken from 11:00 a.m. to 3:30p.m. in 15 to16 days in a month. The radiation level changes every time, so to cope

   up with same the gap betwen every set of reading was fifteen minutes. With the help of temperature gun (infrared temperature sensor) the solar panel temperature was taken for every instant in every different pressure. The readings were taken from the month of November, 2010 to April, 2011. So the data has been taken for winter as well as summer.

3. Sample test result

The results are taken in the tabular form in a note book. Sample copy is given in TABLE 2.1. by which we can calculate diurnal variations.

TABLE 2.1. Sample data sheet on dated 25.01.2011.

1. Result

   Based on the experimental data for the period of six month (November, 2010 to April, 2011) the SPV module efficiency and overall efficiency of the system have been calculated for both the systems. And the results are represented in graphical form for showing the

   comparative analysis of various parameters (i.e. temperature, SPV panel/module efficiency, system efficiency and solar radiation in different months) for both the systems.

   Fig.3.1 November D.P 0.5 Kg/cm2 Fig.3.2 December D.P 0.5 Kg/cm2

   Fig.3.3 January DP 0.5 Kg/cm2 Fig.3.4 February DP 0.5 Kg/cm2

   Fig.3.5 March DP 0.5 Kg/cm2 Fig.3.6 April DP 0.5 Kg/cm2

   Fig.3.7 November DP 1 Kg/cm2 Fig.3.8 December DP 1 Kg/cm2

   Fig.3.9 January DP 1 Kg/cm2 Fig.3.10 February DP 1 Kg/cm2

   Fig.3.11 March DP 1 Kg/cm2 Fig.3.12 April DP 1 Kg/cm2

   Nomenclature:

   1. SPVPS1 Solar Photovoltaic Pump System 1 which have panel/module cooling and cleaning arrangement by water spray mechanism.

   2. SPVPS2 Solar Photovoltaic Pump System 2 which have no panel/module cooling and cleaning arrangement by water spray mechanism.

   3. System1 indicate SPVPS1 and System2 indicate SPVPS2.

   4. Panel1 and Panel2 efficiency indicate efficiency of the modules SPVPS1 and SPVPS2 respectively.

   5. Temp1 and Temp2 indicate the temperature of the modules SPVPS1 and SPVPS2 respectively.

   6. DP Pump discharge pressure.

3.2. Discussion

Already it has been mentioned that the main objective of this present work was to know how much system efficiency increased, and panel efficiency increased with lowering the temperature in SPVPS1 as it is cooled and cleaned by water spray. A comparative graphical representation has been made between spvps1 and spvps2 for different discharge pressure in different months to show the higher efficiency of SPVPS1 than SPVPS 2 for its lower panel temperature.

From the graphical representation we can conclude that SPVPS1 is more efficient than SPVPS2 as it posses at least 10C lower module surface temperature than SPVPS2.

From the figures 3.1-3.12, where system efficiency and temperature variation are depicted SPVPS1 has high efficiency than the other SPVPS2 with at least 10C temperature difference at differet discharge pressure. But the main thing is that the system efficiency of both the system is quiet lower. Because the system efficiency is the combination of PV panel efficiency and Motor- pump set efficiency. As the Solenoid type diaphragm pump is used here as motor pump unit which has lower efficiency than the conventional motor coupled with centrifugal pump unit, ultimately lower the overall efficiency.

From the module efficiency and temperature variation, we found that during the month of November, December, January the variation is noticeable. In that cases the module of SPVPS1 touches highest peak of efficiency than the module of SPVPS2 and panel 1 posses lower temperature than panel 2. Sometimes that difference of temperature was reached at least 11C -19C. During that time tilt factor is reaching 1.2 – 1.6. And we know that received quantity of solar radiation is another parameter that affects the solar cell temperature, because part of the incident radiation transformed into heat within the semiconductor that heat is proportional to the value of received solar radiation, which is also affected by the inclined surfaces. Another thing is that, during said seasons the atmospheric temperature is quiet high and continuously dust particle deposited on panel 2 (SPVPS2), that the combinational heating effect of that two increase the panel temperature of SPVPS2; On The other hand, SPVPS1 is continuously cleaned and cooled by water spraying mechanism and increment of temperature of panel1 is restricted. But when we observe the graphical representation of March and April, (tilt factor is 0.8-0.9) we can

observe that the panel efficiency and the temperature variation of the panel is like to be same or it will better to say that the variation is not so noticeable. the reason behind it that during that time the seasonal rain fall occur in the west Bengal so as a result natural cleaning happen in panel of SPVPS2 system. Besides during afternoon season wind flow occur so, it reduced the ambient temperature so in that time the variation is slight different.

It is also noticeable that the SPVPS1 system shows maximum system efficiency (6.486%) at 1kg/cm2 discharge pressure in the month of March at the solar radiation of 615.143 W/m2 at 35C of its panel temperature with maximum spv panel efficiency (12.25%). While SPVPS2 system shows 5.288% system efficiency with 11.442% spv panel efficiency at the panel temperature of 40C having the same other conditions.

1. Conclusion

   From the above discussion it is clear that the SPVPS1 has the better performance characteristic than SPVPS2 as a continuous cooling process is there. Another noticeable thing is that stand alone solar SPV system works in its best form in the cold and winter seasons. As per BEBC code our country is placed in the hot and humid climate zone so, efficient cooling process is required to develop. At last we can say proper utilization of resources like the energy from the sun should be justified by technically with good management study in form of pay-back period. Here, we successfully reduce the module temperature by using a simple low cost method and increase the SPV pumping efficiency that will satisfy to have a less payback period.

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