A. Abete, R. Napoli, F. Spertino

Politecnico di Torino, Corso Duca Abruzzi 24, 10129 Torino (Italy)

Tel. +39-11-564.7105 Fax +39-11-564.7199 Email filippo. spertino@ polito. it

Introduction — PhotoVoltaic (PV) plants are already economically viable in off grid sites (mountains, islands and rural areas), as for solar home systems, or where the grid is far some kilometres, as for road lighting. Technical problems are still present and different standards have been proposed for quality assurance, i. e. the “Universal Technical Standard for Solar Home Systems”: it is a design guideline for manufacturers and installers, which gives requirements classified as compulsory, recommended and suggested; especially they deal with batteries, identified as the most costly component during the system lifetime (operation and maintenance), and charge regulators [1]. The simulation of battery behaviour in PV systems is an usual topic and several mathematical models have been developed with different degrees of complexity: the challenge is to find a good compromise between complexity and precision [2]. This question is still existing, because often models consider battery charges and discharges only at constant current, contrary to what occurs in the stand alone PV systems with various types of load (household appliances, motors, lamps, etc.). With reference to a stand alone PV system for road lighting, this paper deals with firstly the experimental characterisation of batteries by a cycle of discharge-charge and then the simulation of yearly system behaviour by the battery parameters for determining reliability and black-out hours.