Low-Cost Electronics for Online I-V Tracing at Photovoltaic Module Level: Development of Two Strategies and Comparison between Them

Abstract

The measurement of current–voltage (I-V) curves of single photovoltaic (PV) modules is at this moment the most powerful technique regarding the monitoring and diagnostics of PV plants, providing accurate information about the possible failures or degradation at the module level. Automating these measurements and allowing them to be made online is strongly desirable in order to conceive a systematic tracking of plant health. Currently, I-V tracers present some drawbacks, such as being only for the string level, working offline, or being expensive. Facing this situation, the authors have developed two different low-cost online I-V tracers at the individual module level, which could allow for a cost-affordable future development of a fully automated environment for the tracking of the plant status. The first system proposed implements a completely distributed strategy, since all the electronics required for the I-V measurement are located within each of the modules and can be executed without a power line interruption. The second one uses a mixed strategy, where some common electronics are moved from PV modules to the inverter or combiner box and need an automated very short disconnection of the modules string under measurement. Experiments show that both strategies allow the tracing of individual panel I-V curves and sending of the data afterwards in numerical form to a central host with a minimum influence on the power production and with a low-cost design due to the simplicity of the electronics. A comparison between both strategies is exposed, and their costs are compared with the previous systems proposed in the literature, obtaining cost reductions of over 80–90% compared with actual commercial traces.

Configurable IoT Open-Source Hardware and Software I-V Curve Tracer for Photovoltaic Generators

“…Reference [7] identifies various trends in the advancement of curve tracers, among which low-cost measurement systems and low-cost communications are highlighted. In the same sense, the important role that reliable low-cost communications play is emphasized in [15].…”

“…For diagnosis, electrical parameters are extracted from the measured I-V curves such as the short circuit current, the open-circuit voltage, the maximum power-point, and the fill factor [6,14]. Indeed, decisions on the replacement of faulty or degraded devices are better taken based on a direct measurement than based on estimation [15].…”

“…A curve tracer developed around a commercial low-cost embedded microcontroller (TivaC) is presented in [24]. Additionally, a low-cost microcontroller is the core of the curve tracer presented in [15], where measurements are stored in local memory and downloaded through a universal synchronous asynchronous receiver transmitter (USART) connected to a Bluetooth device.…”

A Resonant Ring Topology Approach to Power Line Communication Systems within Photovoltaic Plants

“…Monitoring and maintenance tasks within solar plants are becoming the focus of many research efforts, and a growing number of sensors and measuring devices are proposed to be installed along different points of the solar module associations, even within each solar module [1]. In this scenario, communications between solar modules and centralization points (combiner boxes) become an essential subject for research.…”

Design of a Low-Cost Multiplexer for the Study of the Impact of Soiling on PV Panel Performance

“…Unfortunately, the cost of commercial kits or ensemble equipment could be higher than 10,000 e. One alternative is to find separate, cheaper devices and then to try to couple them with each other. In this regard, a large number of different solutions are available on the market, in order to trace the I-V curve of a module, including capacitive loads, electronic loads, bipolar power amplifiers, four-quadrant power supplies, and direct current/direct current (DC/DC) converters, some of which correspond to low-cost research prototypes [32][33][34].…”