In this paper we describe a programmable electrical low-cost system, destined to characterize the functioning of photovoltaic modules and to compare their performances under variable climatic conditions (temperature, humidity). The system is based on a circuit compound of several resistors, sensors and an Arduino board programmed to sweep all the resistances, in intervals of precise time and this after choosing each photovoltaic module, acquiring data from sensors and sending them to the computer. It is very important to mention that the developed system is physically separated by the production unit and it provides one characteristic in one minute or less, a period during which all parameters are assumed to be invariant. The number of points (resistors) can be also increased by simply changing the program inside electronic board. The experimental results are in agreement with the data provided by the manufacturer and the numerical simulation. Finally it can be noted that this device is less expensive and feasible to automatic measurements. Thus it can be considered as a practical solution especially for experiences stretching over long periods.