This paper presents a wireless communications system that was used to monitor a photovoltaic source. Basically, the microcontroller-based Data Acquisition card measures solar radiation from a pyranometer and energy produced by the PV source through an energy meter. These data is transmitted in a wireless channel at 2.4 GHz by using low-cost and low-power consumption RF modules. In the monitoring room, another electronic card, based on microcontroller, RF module and USB interface, receives the data and then the information is stored in a local database. A Java user interface was developed to access the data from a PC. We ran speed and BER tests to demonstrate the reliability of the proposed system. As a result, we obtained a bit rate of 26.73 Kbps and a Bit Error Rate (BER) of 0.5%.