Development of Mathematical Equation for Photovoltaic Array Internal Resistance Measurement under Operating Conditions

Abstract:

A novel technique has been developed for PV array internal resistance measurement while keeping the plant in operation in contrary to flash test or basic equation (E_b) for which the modules need to be disconnected from the system. We present an equation developed for the array’s internal resistance measurement for PV technologies namely Amorphous Silicon (a-Si), Poly Crystalline Silicon (p-Si) and Hybrid Crystalline Silicon (HIT). Monthly Measured I-V characteristic curves of PV Array were converted to Standard Test Conditions following the IEC 60891 standard. Multiple regression analysis and linear regression technique were used to develop the equation for estimating the PV array internal resistance. The developed equations (E_d) will find the relationships of the 4 variables that are Series resistance (R_s), Shunt resistance (R_sh), maximum voltage (V_m) and maximum current (I_m). The results revealed that the E_d can be applied to measure the PV array internal resistance value with low error margin than E_b. The series resistance calculated using E_d is higher than E_b about 1.11 %, 1.88 % and 0.87 % for a-Si, p-Si and HIT respectively. The shunt resistance calculated using E_d is higher than E_b about 0.07 %, 0.09 % and 0.09% for a-Si, p-Si and HIT respectively.

• Periodical: Applied Mechanics and Materials (Volume 839)
• Pages: 59-64
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.839.59
• Online since: June 2016
• Authors: Nattawut Khaosaad, Nipon Ketjoy*, Sarayooth Vaivudh, Kobsak Sriprapha
• Keywords: Internal Resistance, Mathematical Equation, Photovoltaic Array

References

[1] Ming-Kun Lee , Jen-ChunWang, Sheng-FuHorng and Hsin-FeiMeng. Extraction of solar cell series resistance without presumed current–voltage functional form. Solar Energy Materials & Solar Cells 94 (2010) 578-582.

DOI: 10.1016/j.solmat.2009.11.026

[2] M.W. Denhoff and N. Drolet. The effect of the front contact sheet resistance on solar cell performance. Solar Energy Materials & Solar Cells 93 (2009) 1499-1506.

DOI: 10.1016/j.solmat.2009.03.028

[3] E.E. van Dyk and E.L. Meyer. Analysis of the effect of internal resistances on the performance of photovoltaic modules. Renewable Energy 29 (2004) 333-344.

DOI: 10.1016/s0960-1481(03)00250-7

[4] Ryan C. Campbell. A Circuit-based Photovoltaic Array Model for Power System Studies. IEEE 39 (2007) 97-101.

[5] Priyanka, Mohan Lal, S.N. Singh. A new method of determination of series and shunt resistances of silicon solar cells. Solar Energy Materials & Solar Cells 91 (2007) 137-142.

DOI: 10.1016/j.solmat.2006.07.008

[6] S.R. Wenham, M.A. Green and M.E. Watt. Applied Photovoltaics (2007).

[7] Nipon Ketjoy, Chatchai Sirisamphanwong and Nattawut Khaosaad. Performance evaluation of 10 kWp photovoltaic power generator under hot climatic condition. Energy Procedia 34 (2013) 291–297.

DOI: 10.1016/j.egypro.2013.06.757

[8] International Standard IEC 61829. Crystalline silicon photovolatic (PV) array - On-Site measurement of I-V characteristics (1995).

[9] International Standard IEC 60891. Photovoltaic devices - Procedures for temperature and irradiance corrections to measured I-V characteristics (2009).

[10] Chattariya Sirisamphanwong, Nipon Ketjoy. Impact of spectral irradiance distribution on the outdoor performance of photovoltaic system under Thai climatic conditions. Renewable Energy 38 (2012) 69-74.

DOI: 10.1016/j.renene.2011.07.008