This paper describes a monitoring architecture for stand-alone photovoltaic (SAPV) systems. For the proposed system a web application has been adopted, thus allowing an on-line monitoring and control of remote installations. Moreover, daily reports are elaborated and sent to the system operator. These data can be analysed off-line to calculate both energy performances indices and statistical values. Historical data analysis is useful not only to optimize the operation of the system but also to design a retrofit of the SAPV system. To check the effectiveness of the proposed remote monitoring system, the performance of a photovoltaic-powered outdoor refrigerator has been evaluated. In case of temperature-sensitive application, such as vaccines or perishable goods storage, critical operating conditions have been detected. Experimental measurements executed on a prototype, adapted for outdoor operation with a horizontal PV module, show that the refrigerator works adequately in the given place (Catania-Italy), where typical Mediterranean climate is present, if an additional vertical PV module is adopted.