Theoretical analysis of integrated photovoltaic system and design of an optimised battery voltage regulator

• Published in: Solar energy materials and solar cells 1995-05, Vol.37 (2), p.159-174
• Main Authors: Mishra, P.R., Pandey, A.K., Joshi, J.C
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Exact sciences and technology; Natural energy; Solar energy; Solar energy storage
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/0927-0248(94)00204-5

A precise theoretical model of an integrated photovoltaic system has been developed to find out the effect of temperature, battery voltage and voltage drop (across the battery voltage regulator (BVR) and interconnecting wire) on the charging current delivered by the photovoltaic array. The theoretical analysis predicts that voltage drop is a significant parameter, which when decreasing in the system results in a considerable increase of the charging current. Based on the above theoretical requirements a Battery Voltage Regulator (BVR) has been designed, fabricated and tested. The results show that due to reduction in the voltage-drop, there is a gain in the charging current of about 5% at 25° C with respect to a conventional BVR for a 12 V system. In the worst case, when the ambient temperature rises to above 45°C, the current-gain increases to 10%. The charging current is regulated by the pulse-width modulation technique to automatically meet the load demand and self discharge of battery-bank (since the battery-bank is never disconnected once the battery-bank is fully charged). Therefore, the load voltage regulation is not required. This technique is superior to the conventional techniques because it does not require field adjustment and knowledge of load characteristics by the user. The net BVR can be easily extended for higher voltage systems. The theoretical analysis is also important for a PV system designer, because one can augment the system for available BVR and interconnecting wire with the help of this,.