Available online at www.jtusci.info ISSN: 1658-3655 Benghanem & Alamri / JTUSCI 2: 94-105 (2009) ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ Modeling of photovoltaic module and experimental determination of serial resistance Mohammed S. Benghanem 1 & Saleh N. Alamri 2 1&2 Department of Physics, Faculty of Sciences, Taibah University, Al-Madinah Al-Munawrrah, KSA Received 29 June 2008; revised 6 August 2008; accepted 9 August 2008 Abstract An explicit model is presented for accurate simulation of the I-V curve characteristic of photovoltaic (PV) module. The model is compared with the traditional I-V curve characteristic and to some experimental results to show the accuracy of the method. The explicit model proposed is found to be reliable and accurate in situations where this model is a good approximation of cell or module performance. Also, an experimental method is presented to determine the series resistance and shunt resistance of the PV cells and PV modules. Keywords: I-V characterization; Simulation models; Experimental measurement; Series resistance; Shunt resistance. Benghanem & Alamri / JTUSCI 2: 94-105 (2009) 95 2. Review of Existing models of solar cell 1. Introduction The determination of solar cell model Characteristic parameters from experimental data is important in Several models of PV generator have been the design and evaluation of solar cells. developed in literature [1-6]. The aim is to get the The work described in this paper is to characterize I-V characteristic in order to analyze and evaluate the photovoltaic (PV) modules in real conditions. the PV systems performance. The difference Also, we give a method to determine the serial between all models is the number of necessary resistance RS and the shunt resistance RSh of PV parameters used in the computational. The most module. The serial resistance is mainly the sum of models used are: • • • • contact resistance on the front and back surfaces and the resistances of the bulk and the diffused layer on the top. The shunt resistance represents a parallel high-conductivity path across the p-n junction. The shunt resistance can affect the short circuit current ISC density as well. The PV performance depends on the values of RSh and RS. Therefore, RS and RSh both need to be recognized and understood in order to analyze the cell and module performance. The most commonly used method for measuring the series resistance of a solar cell was first proposed by wolf and Explicit Model Solar Cell Model using four parameters Solar Cell Model using five parameters Solar Cell Model using two exponential 2.1. Explicit Model This model needs four input parameters, the short-circuit current ISC , the open-circuit voltage VOC , the maximal current Im, and the maximal voltage Vm [2]. The relation between the load current I and the output voltage V is given by: ⎡ ⎛ ⎛ V I = I SC ⎢1 − C1 ⎜ Exp ⎜⎜ ⎜ ⎢⎣ ⎝ C 2 . V OC ⎝ ⎞ ⎞⎤ ⎟ − 1⎟ ⎥ ⎟ ⎟ ⎠ ⎠ ⎥⎦ (1) Rauschenbach [1]. This involves measuring the characteristic of a cell at two different illuminations. Where ⎛ I C1 = ⎜⎜1 − m I SC ⎝ Several other methods are available in the literature for the measurement of series and shunt resistances [2-6]. All these methods are based on single exponential model of solar cell and assume that RSh is infinite and presume RS to be independent of the intensity of illumination, which may not be valid. In this paper we propose a new approach to simulate the IV characterization by given a photovoltaic resistance for any materials properties of the solar cell. Also, the photovoltaic resistance is given for silicon cell. We present an experimental method for determination of RS and RSh of a solar cell using the I-V characteristic based on explicit model proposed. And ⎛ − Vm ⎞ ⎟.Exp ⎜ ⎜ C .V ⎟ ⎝ 2 OC ⎠ Vm −1 VOC C2 = ⎛ I Ln⎜⎜1 − m I SC ⎝ ⎞ ⎟ ⎟ ⎠ ⎞ ⎟ ⎟ ⎠ 2.2. Solar Cell model using four parameters The classical equation describing the I-V curve of a single solar cell is given by: ⎡ ⎛ q ⎞ ⎤ (V + R S .I ) ⎟ − 1⎥ I = I Ph − I 0 .⎢ Exp ⎜ . . A K T ⎝ ⎠ ⎦ ⎣ Where I is the load current (2) and V the output voltage, I0 is the diode reverse saturation current, IPh is the photo-generated current, RS is the series Modeling of photovoltaic module and experimental determination of serial resistance Benghanem & Alamri / JTUSCI 2: 94-105 (2009) 96 resistance, q is the electric charge, K the Boltzman current Im at the maximum power point and the constant, T is the temperature (oK) and A is the slopes of curve near VOC and ISC. ideality factor. The four parameters of this model Thus: are: IPh, I0, RS, and A. ⎛ dV ⎞ = − RSO ⎜ ⎟ ⎝ dI ⎠V =Voc The effect of shunt resistance is not taking a count in this model. Equation (2) describes the I-V curve quite well, but the parameters cannot be measured (4) ⎛ dV ⎞ = − RSh 0 ⎜ ⎟ ⎝ dI ⎠ I = Isc in a simple manner. Therefore, a fit based on a smaller number of parameters which can be (5) measured easily have been developed [3]. These include: - The open circuit voltage VOC. - The short-circuit current ISC. - The maximum power Pm. The following equations are obtained: A= 2.3. Solar Cell model using five parameters In this model, the effect of shunt resistance is considered [4]. Figure 1 shows a solar cell V m + I m .R S 0 − VOC ⎡ ⎢ ⎛ ⎞ ⎛ V V Vt ⎢ Ln⎜⎜ I SC − m − I m ⎟⎟ − Ln⎜⎜ I SC − OC ⎢ ⎝ R Sh R Sh ⎠ ⎝ ⎢ ⎣⎢ Vt = shunt resistance RSh. ⎛ V I 0 = ⎜⎜ I SC − OC RSh ⎝ I V IPh ID,VD RS = R S 0 − RSh Fig.1. Solar cell equivalent circuit including series resistance and shunt resistance. The mathematical description of this circuit is given by the following equation: ⎞⎤ ⎟⎥ ⎟⎥ ⎟⎥ ⎟⎟⎥ ⎠⎦⎥ (6) Where: equivalent circuit including series resistance RS and RS ⎛ ⎜ ⎞ ⎜ Im ⎟+⎜ ⎟ ⎠ ⎜ I − VOC ⎜ SC R Sh 0 ⎝ K .T q ⎞ ⎛ V ⎟⎟.Exp ⎜⎜ − OC ⎠ ⎝ A.Vt ⎞ ⎟⎟ ⎠ (7) ⎛ V ⎞ A.Vt .Exp ⎜⎜ − OC ⎟⎟ I0 ⎝ A.Vt ⎠ ⎛ ⎛ I .R ⎛ R ⎞ I Ph = I SC .⎜⎜1 + S ⎟⎟ + I 0 .⎜ Exp ⎜⎜ SC S ⎜ R Sh ⎠ ⎝ A.Vt ⎝ ⎝ (8) ⎞ ⎞ ⎟⎟ − 1⎟ ⎟ ⎠ ⎠ (9) (10) RSh = RSh 0 2.4. Solar cell model using two exponential The solar cell equivalent circuit including series ⎡ ⎛ q ⎞ ⎤ V + R S .I I = I Ph − I 0 .⎢ Exp ⎜ (V + RS .I ) ⎟ − 1⎥ − RSh ⎝ A.K .T ⎠ ⎦ ⎣ (3) resistance RS, shunt resistance RSh, two exponential-type ideal junction, a constant photo- The five parameters of this model are: IPh, I0, RS, generated current source is represented by Fig. 2. RSh and A. For a given temperature and solar The mathematical description of this circuit is irradiation given by the following equation [5]: intensity, these parameters are determined by using the open-circuit voltage VOC, the short-circuit current ISC, the voltage Vm and the Modeling of photovoltaic module and experimental determination of serial resistance Benghanem & Alamri / JTUSCI 2: 94-105 (2009) RS 97 I IPh V ID1 ID2 RSh Fig.2. Solar cell equivalent circuit for model with two exponential. ⎡ ⎡ ⎛ q ⎞ ⎤ ⎛ q ⎞ ⎤ V + R S .I I = I Ph − I 01 .⎢ Exp ⎜⎜ (V + R S .I ) ⎟⎟ − 1⎥ − I 02 .⎢ Exp ⎜⎜ (V + R S .I ) ⎟⎟ − 1⎥ − R Sh ⎢⎣ ⎢⎣ ⎝ A1 .K .T ⎠ ⎥⎦ ⎝ A2 .K .T ⎠ ⎥⎦ The parameters of this model IPh, A1, A2, I01, I02, RS and RSh are determined by the following X 2V = − approximations [5]: IPh= ISC I Ph 1 I 02 = . 2 ⎛ ⎛ e.V ⎞ ⎞ ⎜⎜ Exp⎜ − OC ⎟ − 1⎟⎟ ⎝ 2.K .T ⎠ ⎠ ⎝ (12) a simplified relation for RS as: ⎡ dV RS = − ⎢ ⎣ dI (13) + X 1V RSh = − (14) e.I 01 ⎛ e.V ⎞ .Exp⎜ − OC ⎟ K .T ⎝ K .T ⎠ ⎤ 1 ⎥ + X 2V ⎦ X 1V (17) 1 ⎡ ⎢ ⎢ ⎢ ⎛ dV ⎢⎜ ⎢⎣ ⎜⎝ dI ⎤ ⎥ 1 ⎥ + X 1i + X 2i ⎥ ⎞ ⎥ + RS ⎟⎟ ⎥⎦ I = Isc ⎠ (18) Where: With: X 1V = − + The shunt resistance RSh is deduced from equation V= VOC : V =Voc V =Voc (14) with I= ISC RS is obtained by derivation of equation (11) at ⎤ ⎥ 1 ⎥ 1 ⎥ + X 2V + RSh ⎥⎦ (16) 1 << (X1V + X2V), we can obtain R Sh If we consider I Ph 1 I 01 = . 2 ⎛ ⎛ e.VOC ⎞ ⎞ ⎜⎜ Exp⎜ − ⎟ − 1⎟⎟ ⎝ K.T ⎠ ⎠ ⎝ ⎡ ⎢ dV RS = ⎢ ⎢ dI ⎢ ⎣ e.I 02 ⎛ e.VOC ⎞ .Exp⎜ − ⎟ A.K .T ⎝ A.K .T ⎠ (11) ⎞ ⎟⎟ ⎠ X 1i = ⎛ I .R I 01 Exp ⎜⎜ SC S Vt ⎝ Vt X 2i = ⎛ I .R I 02 Exp ⎜⎜ SC S A.Vt ⎝ A.Vt (15) Modeling of photovoltaic module and experimental determination of serial resistance (19) ⎞ ⎟⎟ ⎠ (20) Benghanem & Alamri / JTUSCI 2: 94-105 (2009) 3. Comparison with experimental 98 3.2. Four parameters Model This method is based on single exponential Characteristic model of solar cell and assumes that RSh is 3.1. Explicit Model Fig.3 shows that the model gives a infinite, an assumption that may not be valid for best representation of I-V curve, but the the cell having low RSh values. limitation of this method is that it doesn't take Fig.4 shows the I-V curve given by this method. account of serial resistance RS and shunt We note a difference between experimental I-V resistance RSh. curve and those simulated in non-linear region near the maximum power point. Explicit model Experimental data 3 Current (A) 2.5 2 1.5 1 0.5 0 0 2 4 6 8 10 12 14 16 18 20 Voltage (V) Fig. 3. The I-V characterization using explicit model at 800 W/m2 and 45oC. Three parameters model Experimental data 3 Current (A) 2.5 2 1.5 1 0.5 0 0 2 4 6 8 10 12 14 16 18 20 Voltage (V) Fig. 4. I-V characterization using four parameters model at 800 W/m2 and 45oC. Modeling of photovoltaic module and experimental determination of serial resistance Benghanem & Alamri / JTUSCI 2: 94-105 (2009) 99 Where n is the number of data, Isi is the ith 3.3. Five parameters model Fig.5 shows the I-V characterization given simulated current and Imi is the ith measured by the five parameters model. current. The RMSE test provides information on The five parameters model is shown to give the short-term performance of the simulation accurate reliable results but gives non-physical model. The lower value of RMSE means the values at low illuminations [4]. more accuracy for the model used. In order to evaluate the accuracy of the models a The RMSE values of the models were calculated. statistical tests was used [7], root mean square Table 1 shows the RMSE values obtained from error (RMSE). The RMSE is given as follow: the models presented. The RMSE average values, which are a measure of the accuracy of estimation, have been found to be the lowest for ⎛1 ⎞ RMSE = ⎜ ∑ ( I si − I mi ) 2 ⎟ ⎝ n i =1 ⎠ n 1/ 2 Five parameters model (RMSE = 0.022) at (21) illumination of 800 W/m2. Five parameters model Experimental data 3 Current (A) 2.5 2 1.5 1 0.5 0 0 2 4 6 8 10 12 14 16 18 20 Voltage (V) Fig. 5. I-V characterization using five parameters model at 800 W/m2 and 45oC. Table.1. RMSE values for each model Solar irradiation (Wh/m2) 1000 800 Temperature (oC) 25 45 Explicit model 0.039 0.027 Four parameters model 0.047 0.104 Five parameters model 0.095 0.022 RMSE Modeling of photovoltaic module and experimental determination of serial resistance Benghanem & Alamri / JTUSCI 2: 94-105 (2009) This means the good estimation of I-V By using the following simplification: characterization by using a five parameters model than the three parameters model and the explicit model for the illumination of 800 W/m2. 100 e ⎛ V + RPV . I ⎜⎜ VT ⎝ ⎞ ⎟⎟ ⎠ >> 1 and IPh= ISC The I-V curve can be expressed as: 4. Explicit model proposed Measurements of peak-power and internal series resistance under natural ambient conditions need I = I SC ⎛ V +VR − I 0 .⎜ e ⎜ ⎝ ⎞ ⎟ ⎟ ⎠ (24) ⎞ ⎟ − R PV .I ⎟ ⎠ (25) PV .I T mathematical corrections of the measured I-V characteristic, considering irradiance and cell temperature. The purpose of I-V characteristic approximation by means of equivalent circuit diagrams lies in the explicit calculability of matching problems between solar generators and several loads. The equivalent circuit diagram for the effective solar cell characteristic is given by Fig.6. R PV I SC − I =e I0 V + RPV . I VT Then: ⎛I −I V = VT .Ln ⎜⎜ SC ⎝ I0 Since I0, VT and RPV are unknown, three conditions are required to enable use of this fit: I 1. If I=0, then V=VOC. 2. At the maximum power point the fit is IPh tangent to the hyperbola Pm= V.I ID , V D V Fig. 6. Equivalent circuit diagram for Effective solar cell characteristic. The slope S at the open circuit voltage is 3. to be considered. The condition (1) yields: VOC = V The effective solar cell characteristic is given by the following model: ⎛ V +VR I = I ph − I 0 ⎜ e ⎜ ⎝ PV . I T ⎞ − 1⎟ ⎟ ⎠ VT = (22) ⎛I = VT .Ln⎜⎜ SC ⎝ I0 I =0 VOC ⎛I Ln⎜⎜ SC ⎝ I0 The explicit version is: ⎛ I ph − I + I 0 V = VT .Ln ⎜⎜ I0 ⎝ RPV ⎞ ⎟⎟ − RPV .I ⎠ I 0 = I SC .e (23) is the photovoltaic resistance, not to be RPV, VT, I0 and IPh. Or: ⎞ ⎟⎟ ⎠ VOC VT (26) and then: (27) The condition (2) can be expressed as: V I =Im = confused with the serial resistance RS. We need to determine the following parameters: − ⎞ ⎟⎟ ⎠ ∂V ∂I Pm Im = I =Im (28) P ∂ ⎛ Pm ⎞ = − m2 ⎜ ⎟ ∂ I ⎝ I ⎠ I =I Im Modeling of photovoltaic module and experimental determination of serial resistance m (29) Benghanem & Alamri / JTUSCI 2: 94-105 (2009) Differentiating equation (29) according to equation is then given by the approximate function [6]: (25), we get: S= VT ∂V =− −R (I Sc − I ) PV ∂I VOC I SC =− I =Im I .V V I ⎛ ⎞ ⎜⎜ α 1 . p max p max + α 2 . p max + α 3 . p max + α 4 ⎟⎟ I SC .VOC VOC I SC ⎝ ⎠ With the equation-constants: For I =Im, we get: ∂V ∂I 101 P VT − R PV = − m2 (I SC − I m ) Im ⎛ − 5.411 ⎞ ⎜ ⎟ ⎜ 6.450 ⎟ α =⎜ 3.417 ⎟ ⎜ ⎟ ⎜ − 4.422 ⎟ ⎝ ⎠ (30) Then: We note that the equation (36) is independent of R PV = Vm VT − I m (I SC − I m ) (31) material properties of the solar cell. The RPV is calculated using equation (34) for By substituting equation (26) in equation (31), we silicon cell or using equation (36) for any materials get: properties of the solar cell. The value of RPV is RPV VT = V = m − Im substituted into equation (22) to find the I-V curve VOC (I SC ⎛I − I m ).Ln ⎜⎜ SC ⎝ I0 ⎞ ⎟⎟ ⎠ (32) of a single solar cell. 4.1. VOC V = OC 7 16.11 Ln10 Comparison between Explicit model proposed and experimental data Fig. 7 shows a good agreement between experimental I-V curve and those given by the ⎡ ⎤ 16.11 I = I SC ⎢1 − 10 − 7.Exp (V + R PV .I ) ⎥ VOC ⎣ ⎦ (33) explicit model proposed for different illuminations. Explicit model (1000 W/m2) Explicit model (800 W/m2) Experimantal data at 1000 W/m2 Experimental data at 800 W/m2 equation (33) yields: RPV = Vm VOC − I m 16.11(I SC − I m ) 3 dV dI =− I =0 C urrent (A ) The condition (3) yields: S= VT −R (I Sc ) PV 2.5 2 1.5 1 Then: 0.5 VT = − (S + R PV ).I SC (35) Substituting equation (35) into equation (31), we get: RPV = − S 3.5 (34) I SC Vm ⎛ I ⎜⎜1 − SC + Im Im ⎝ Im ⎞ ⎟⎟ ⎠ (36) 0 0 2 4 6 8 10 12 14 16 18 20 Voltage (V) Fig. 7. I-V curve characterization for two illuminations. Fig. 8 shows the I-V curve of the explicit model proposed with experimental data and comparison Modeling of photovoltaic module and experimental determination of serial resistance Benghanem & Alamri / JTUSCI 2: 94-105 (2009) 102 with others models studied. The RMSE values obtained for the explicit model proposed is 0.01 for the illumination of 800 W/m2 and 0.03 for the illumination of 1000 W/m2. The experimental I-V curve is given by the curve tracer (PVPM 2540C) for PV modules (Fig.9). Five parameters model Three parameters model Explicit model proposed Experimantal data Fig. 9. PVPM 2540C: Curve Tracer for PV Modules. 4.2. New Experimental method for calculation of 3 Rs and RSh Current (A) 2.5 RSh is calculated near the two points P1 and 2 P2 on the illuminated I-V characteristic. P1 is near 1.5 the short-circuit point and thus corresponds to a 1 low value of voltage; P2 is near the maximum power point and therefore corresponds to a higher 0.5 0 voltage. 0 2 4 6 8 10 12 14 16 18 20 Voltage (V) Fig. 8a. Simulation and Experimental I-V Curve for illumination at 800 W/m2. RS is calculated near the two points P3 and P4 on the illuminated I-V characteristic. P4 is near the open-circuit point (V= Voc) and P3 is near the maximum power point. The choice of the four working points P1, P2, P3 and P4 is deduced by iteration using the algorithm Five parameters model Three parameters model Explicit model proposed Experimantal data given below. 4.2.1. Methodology The condition (3) gives: 3.5 Current (A) 3 S= 2.5 dV dI I =0 2 This condition means to find a slope near the open 1.5 circuit voltage VOC. So, experimentally we chose 1 two working points P4 corresponding to the 0.5 0 coordinates ( I4, V4) and P3 with the coordinates 0 2 4 6 8 10 12 14 16 18 20 Voltage (V) Fig. 8b. Simulation and Experimental I-V Curve for 2 illumination at 1000 W/m . (I4, V4). Then, the slope S is given by: S= V − V3 dV = RS = 4 dI I3 − I 4 Modeling of photovoltaic module and experimental determination of serial resistance (37) Benghanem & Alamri / JTUSCI 2: 94-105 (2009) : I4 =0 ( V4 = VOC ) and I3 is given by iteration ⎛ I ph − I i + I 0 Vi = VT .Ln ⎜⎜ I0 ⎝ until we find the value of RS equal to the experimental value RSM 103 measured by the ⎞ ⎟⎟ − R S .I i i = 1 to 4. ⎠ The following examples show the accuracy of this method. Measuring device and curve tracer for PV modules and strings (PVPM 2540C) as shown in Fig.10. 3 P2 P1 Current (A) 2.5 2 P3 1.5 1 0.5 0 Fig. 10. RSM measurement of PV module by PVPM P4 0 4 6 8 10 12 14 16 18 20 Voltage (V) 2540C. Fig. 11. Experimental working points. Algorithm Example V4 = VOC , I4 = 0 ; Monocrystalline PV-Module Voc =20.51 V I3 varies from 0 to ISC ; Vm =16.58 V From each values of I3, we get V3 ( equ.23) and Im = 3.01 A then we calculate RS (equ.37). Isc = 3.34 A If the calculated value of RS is not equal to RSM, we increase the value of I3 until the value of The I-V characteristic of the PV-module Isophoton RS is given by Fig.12. We have found: RS = 0.64 reaches the measured value RSM. We have find that Ω and RSh = 89.42 Ω. I3 is equal to 50 % of ISC. 3.5 The shunt resistance RSh is given by the relation: P1 3 (38) The optimal choice is given by (Fig.11): I1 = ISC (V= 0v) for the point P1. I2= 95 % of ISC for the point P2. P2 2.5 Current (A) V2 − V1 I1 − I 2 1: Isophoton Vm, Im, ISC and RSM are fixed ; RSh = 2 2 P3 1.5 1 I3 = 50 % of ISC for the point P3. I4 = 0 (V = Voc) for the point P4. The different voltages V1, V2, V3 and V4 corresponding to each working points P1, P2, P3 and P4 are given by using the equ.23: 0.5 0 P4 0 5 10 15 20 25 Voltage (V) Fig. 12. Experimental working Monocrystalline PV-Module Isophoton. Modeling of photovoltaic module and experimental determination of serial resistance points for Benghanem & Alamri / JTUSCI 2: 94-105 (2009) 104 Example2: Monocrystalline PV-Module BP585F The values of series and shunt resistance are given Voc =22.3 V in table 2. We note that for the same illumination, Vm =18 V the series resistance of the PV module BP585F is Im = 4.72 A the lower. The high value of shunt resistance is Isc = 5 A given by the PV module Isophoton. We have found: Rs = 0.50 Ω and Rsh = 77.75 Ω Fig.13 shows the I-V characteristic experimental manipulation of the Table.2. Values of series and shunt resistances for for different PV modules PV-Module BP585F. PV modules Isophoton BP585F MSX 40 RS (Ω) 0.64 0.50 3.06 RSh (Ω) 89.42 77.75 63.83 PV module BP585F 5 P1 4.5 P2 4 Current (A) 3.5 5. Conclusion 3 The explicit model proposed for the I-V curve P3 2.5 2 is shown to give accurate reliable results. This 1.5 model gives parameter values with good precision. 1 Also, the experimental determination of serial 0.5 0 resistance RS and shunt resistance RSh is more P4 0 5 10 Voltage(V) 15 convenient method. A theoretical expression given 20 Fig. 13. I-V characteristic for the PV-module BP585F. RPV for any materials properties of the solar cell. If Example3: I-V curve approximation using silicon cell the photovoltaic resistance is Figure 14 shows the I-V curve for some modules given by equation (34). The value of RPV is by using the explicit model proposed. substituted into equation (22) to find the I-V curve of a single solar cell or PV module. PV module Isophoton PV module Solarex PV module BP585F 3.5 Acknowledgements 3 We wish to thank the Deanship of Scientific Research Taibah University 2.5 Current (A) in equation (36) gives the photovoltaic resistance financially supported this work, under contracted research 2 project 33/427. 1.5 References 1 0.5 0 who 0 5 10 15 20 25 30 35 40 Voltage (V) Fig. 14. I-V characterization for different modules using the explicit model proposed. [1] M. Wolf and H. Rauschenbach. Advanced Energy Conversation, 3, 455 (1963). [2] G. W. HART. Residential photovoltaic system simulation electrical aspect. IEEE, pp.281-288, 1982 [3] S. SINGER, B. ROZENSHTEIN and S. SAURAZI. Characterization of PV array Modeling of photovoltaic module and experimental determination of serial resistance Benghanem & Alamri / JTUSCI 2: 94-105 (2009) output using a small number of measured parameters. Solar Energy, Vol.32, No5, pp.603-607, 1984. [4] D. S. H. CHAN, J. R. PHILIPS and J. C. H. PHANG. A comparative study of extraction methods for solar cell model parameters. Solid State Electronics, Vol. 37, pp.123-132, 1995. [5] J.A. GOW, C.D. MANNING. Development of a photovoltaic array model for use in power-electronics simulation studies. 105 IEEE Proc.Electr. Power Appl., Vol. 146, No.2, pp.193-200, 1999. [6] C. Bendel and A. Wagner. Photovoltaic measurement relevant to the energy yield. WCPEC-3, World Conference on Photovoltaic Energy Conversion, Osaka, Japan, 2003, Pr.No 7P-B3-09, PP.1-4. [7] Ma, C.C.Y. and Iqbal, M. Statistical comparison of solar radiation correlations monthly average global and diffuse radiation on horizontal surfaces. Solar Energy, 1984, 33, 143-148. Modeling of photovoltaic module and experimental determination of serial resistance