A research group from Colombia has conceived a new portable electronic device that enables on-site measurements of the I-V and P-V curves of photovoltaic panels and can reportedly compete with similar but more expensive and difficult-to-handle technologies that are available in the market.
The new tool includes a 240 MHz Tensilica LX6 dual-core processor and 4 MB of storage memory. It works by collecting data on solar radiation, ambient temperature, electric current, and voltage signals from the PV panels via a cellphone through a mobile application.
“The collected data, when synchronized with a server, becomes accessible from anywhere and allows analysis using data analytics algorithms and Machine Learning,” the team explained. “This enables the creation of predictive models and the detection of deficiencies in the system by identifying individual components such as end-of-life and poor positioning.”
For the experimental device, the researchers used an ESP32 microcontroller from US-based SparkFun Electronics. “It features a WiFi module capable of connecting to mobile devices,” they said. “It has 28 GPIO pins and also provides support for low-energy Bluetooth connections. The versatility of the ESP32 shines in IoT project execution.”
As for the sensors, the device uses an ACS712 current sensor, a voltage divider consisting of two resistors in series, an NTC 10 K temperature sensor, and an SP Lite2 irradiance sensor. It also uses a switching step-up module XL6009 as a voltage regulator and the ADS1015 module as an analog-to-digital converter. Furthermore, it includes a p-type MOSFET transistor for high-frequency switching, cables and batteries for energy storage.
Image: Fundación Universitaria Los Libertadores, Energy Reports, Common License CC BY 4.0
“The ESP32 serves as the central device in the printed circuit board (PCB) design, where all input and output signals converge,” the scientists further explained. “Each signal has its respective filtering stage. Since the ESP32 has a maximum output of 3.3 V, it is opto-coupled to transmit the signal at 7.4 V, surpassing the required gate-source voltage (VGS) for proper switching.”
The system also has a casing that can be certified to withstand IP55 standards or higher, according to the researchers.
The performance of the portable tool was tested at two different geographic locations and for two different types of photovoltaic panels. Measurements were taken at different times of the day to guarantee the plotting of curves in different radiations. The tests showed that the proposed system can provide results in line with those of conventional devices.
“By utilizing low-cost components like microcontrollers and digital signal processors (DSPs), our development of a photovoltaic performance monitor has revealed valuable economic benefits,” the academics emphasized. “This approach significantly increases the cost-effectiveness and accessibility of PV systems by reducing the overall expense required for monitoring.”
The group estimated the cost of the experimental device and found it could range between $1,000 and $1,200. It also said more advanced systems in the future may even reach a cost between $275,000 and $630,000.
The details of the system can be found in the study “Design and implementation of an autonomous device with an app to monitor the performance of photovoltaic panels,” published in Energy Reports.
“The compact nature of the device allows for expansion in future versions with new functionalities, such as characterization of electrical production systems or improving signals with electronics focused on signal processing to achieve certification of quality according to established standards,” the group concluded.
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