Our customer requested a solar field string monitoring and fault signalling panel to identify electrical and environmental faults that cause energy losses across a large photovoltaic site. Although the inverters displayed total generation, a blown fuse, poor connector or gradual current reduction on a single PV string could remain hidden within the aggregate value.
The maintenance team needed more than remote data access. They required an industrial system that compared string currents, monitored auxiliary contacts in field combiner boxes, classified faults locally and sent a clear alarm to the appropriate personnel.
In short: “Find string-level losses early, identify the affected box and direct maintenance to the correct location.”
Revan Technology designed a distributed system comprising measurement nodes and a central field panel. Nodes in the combiner boxes monitor string currents and dry contacts, while the central panel collects data over RS-485/Modbus and runs threshold and comparison logic locally.
Current assessment does not rely on a fixed lower limit alone. Comparable strings under the same irradiance conditions are evaluated together to distinguish local shading from genuine electrical deviation. Reference irradiance data and a time delay reduce unnecessary alarms during rapidly passing clouds.
The objective was not to add another data screen. It was to create a maintainable field tool that reduces lost generation time and fault-finding effort.
Each combiner-box node reads string currents through galvanically isolated sensor channels. PCB design considerations included insulation distances for the DC field environment, protected inputs, reverse-polarity protection, industrial terminals and surge protection for the communication line. Fuse and surge-protector auxiliary contacts connect to isolated digital inputs.
Channel values are compared with similar strings in the same inverter group and with reference irradiance. An alarm is generated when a defined deviation persists for a configured period; a delay filter rejects brief shading and cloud transients. Hysteresis and the alarm repeat interval limit notification traffic around the threshold.
Field nodes are addressed on an RS-485/Modbus bus. The central controller supervises data integrity and node availability, recording communication loss as a separate alarm. String currents, enclosure temperature, active alarms and recent events appear on the HMI. A GSM module carries critical alarms and status queries, while an event buffer maintains records during link interruptions.
Following commissioning, string-level deviations became visible earlier and with location data, compared with monitoring based solely on inverter total generation.
This project applies Revan Technology’s custom PCB, embedded software and industrial communication capabilities to measurable risk reduction in renewable-energy sites.
For customer confidentiality, the company name, site capacity and product names are omitted. Images are representative and illustrate the functional structure.
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