6 gaurav kumar
Post on 06-May-2015
Embed Size (px)
- 1.INTRODUCTION Increasing electricity demands & fuel prices tempt us for renewable energy sources such as wind power & solar photovoltaic (SPV). Extraction of maximum power from SPV is essential for better performance. SPV performance is greatly influenced by atmospheric conditions such as solar irradiance, cell-temperature, wind speed, etc.
2. SOLAR CELL I-V RELATION AND PARAMETERS Solar cell single p-n junction diode equivalent electrical circuit I and V cell current and voltage, respectively Iph photo-current I0 reverse saturation current Rse series resistance Rsh shunt resistance n diode ideality factor 3. NEED FOR THE METHOD ISC strongly influenced by solar irradiance VOC & FF strongly influenced by temperature Rate of change of VOC with T depends on rate of change of Rsh and Eg with T Rate of change of FF with T depends on rate of change of Rse and V with T Interdependency of performance on electrical parameters plays significant role on at different T 4. ESTIMATION METHODOLOGY: DETERMINATIONOF ISC At ISC point on the I-V curve Hence Iph = ISC (Iph photo-current)MPPA typical I-V characteristic of a solar cell 5. DETERMINATION OF RSH Use of Lagrangian interpolation formula for current Lagrangian multiplier Inverse of dI/dV at SC point gives Rsh 6. DETERMINATION OF RSE Following linear equations are formed as a function of Rse and n Where Rse is found from, Assumption V/Rsh >> IRse/Rsh 7. DETERMINATION OF I0 AND N Using Rsh and Rse, the following linear equations as a function of I0 and n are formed, Where n and I0 are determined as follows,& 8. EXPERIMENTALSolar SimulatorSilicon Solar CellA 4 x 4 cm2 silicon solar cell is tested in a solar simulator with different temperatures of 40, 50 and 60oC. 9. I-V CHARACTERISTICS AND PARAMETERS OF A SILICON CELL TESTED IN THE LABExperimental characteristics match with that of the fitted Parameters obtained by the proposed method 10. I-V CHARACTERISTICS AND PARAMETERS OF A SILICON CELL OF PREVIOUS LITERATURE Synthetic I-V characteristics match with that of the fitted.Ref: Priyanka Singh et al. Solar Energy Materials & Solar cell 92 (2008)Parameters obtained by the proposed method Obtained parameters match almost with those of reported at different temperatures 11. CONCLUSIONS A non-iterative technique is developed for finding parameters of a solar cell tested under different temperatures Technique is applicable to a Si cell with I-V data available in the literature and a Si cell tested in our laboratory Technique is simple and can be employed for different PV cells tested in different irradiance as well 12. ACKNOWLEDGEMENTS NCPRE, IIT Bombay for providing solar simulator through the programme 1000 teachers training for SPV SVNIT, Surat for providing the fund to attend this conference