Invisible string losses
Inverter-level data hides a failed fuse or disconnected string inside normal daily variation. Without per-string current, energy losses keep accumulating across billing cycles and nobody knows which combiner to open.
Industry
Monitor every PV string, not just the inverter total.
Sertel renewable energy monitoring solutions connect string combiner boxes, per-string monitoring, LoRa wireless links and battery monitoring into one Modbus-ready data path. Plant owners, EPCs and O&M teams find the underperforming string long before it shows up as a monthly generation shortfall.
1500 V DC
RATED PV SYSTEM VOLTAGE
36 strings
PER COMBINER BOX
4 km
LORA WIRELESS RANGE (LINE OF SIGHT)
Why string-level data matters
When one string fails quietly, the whole block pays for it.
A solar plant is not one generator. It is hundreds or thousands of PV strings feeding combiner boxes, which feed inverters, which feed the grid. Inverter dashboards report the combined DC input, so a blown fuse, a loose connector, a shaded row or a degrading module group gets absorbed into the average and never raises a flag.
The loss is small enough to ignore and large enough to matter. One dead string on a 24-string input removes roughly four percent of that combiner's output. At inverter level the dip looks like cloud cover or soiling, so it can run for weeks until a thermographic survey or a manual inspection round finally catches it.
Sertel builds the measurement layer that closes this gap. String current, bus voltage, surge protector status, DC switch status and enclosure temperature are captured at the combiner, carried over RS-485, fibre optic or LoRa wireless, and delivered to SCADA as documented Modbus registers. The DC battery banks that keep protection and communication equipment running receive the same channel-level attention.
The challenge
Four blind spots that drain yield from solar and renewable assets.
These issues surface again and again once a plant moves from commissioning into years of daily operation, whether the site is a factory rooftop, a ground-mounted utility park or a floating solar installation.
Slow fault location on large sites
On a plant spread across hundreds of acres, finding a faulty string often means technicians walking row after row with a clamp meter. Every hour of searching is an hour those strings stay offline.
Cabling cost and communication gaps
Running data cable to remote array blocks or floating platforms adds trenching cost and new failure points. When a link drops, SCADA goes blank at exactly the moment fault data is needed most.
Unmonitored backup battery banks
Protection relays, SCADA servers and communication equipment at the plant substation rely on DC battery banks. A weak battery discovered only during a grid disturbance turns a short event into an extended outage.
The Sertel solution
One monitoring chain, from the PV string to the SCADA screen.
Sertel designs its renewable portfolio as connected layers rather than standalone boxes. Protection and combining happen at the array, measurement happens on every string, data travels over the medium that suits each block, and calibration stays in your team's hands. EPCs source the DC monitoring side from one manufacturer, and integrators receive a documented Modbus register map from day one.
String Combiner Box (T-SCB-300)
Combines 1 to 36 strings at 600, 1000 or 1500 V DC with fuse protection, Type I + Type II surge protection and a load-break DC disconnect. IP 66 enclosure, EN 61439-2:2011 compliant, CE and TUV certified, 5-year warranty.
String Monitoring Box (T-SMB-300)
PV junction box that monitors current on each of 1 to 24 strings, plus bus voltage and internal temperature, at up to 1500 V DC with ±0.25% measurement accuracy and automatic alarm notification to maintenance teams.
String Monitoring Card (SEPL300_SMC)
DIN rail card for up to 24 strings using shunt-based current sensing, DC voltage reading up to 2100 V, RTD and digital inputs, and Modbus RTU output over RS-485, fibre optic or optional LoRa.
Wireless Transceiver with Data Logger (T-WT-300)
LoRa gateway connecting up to 30 nodes across 4 km line of sight in the 850 to 930 MHz ISM band, with Gigabit Ethernet, Modbus TCP/IP and 64 GB local storage expandable to 256 GB.
Battery Monitoring System (BMS-BIU-300 / BMS-DL-S-300)
Per-channel voltage, shunt-based current and temperature monitoring for up to 100 battery channels, with an inbuilt database and web access over Ethernet. Rack or portable trolley mounting.
SMC Configuration and Test Software
Desktop application for live dashboards, pass or fail test reports, RF parameter setup and sensor calibration of string monitoring cards over serial port or Modbus TCP.
A single, trusted data path for DC yield and plant health.
- •Current on every monitored string, measured with shunt-based sensing.
- •Surge protector, DC switch and enclosure temperature status in the same register map.
- •RS-485, fibre optic or LoRa wireless, selected block by block to suit the site.
- •Up to one year of local data logging on the wireless gateway to bridge network outages.
- •Backup battery bank health visible from the control room over Ethernet.
Applications
Built for every scale of solar and renewable deployment.
Utility-scale solar parks
String-level data across every combiner lets IPPs compare block performance against expected yield and send O&M crews directly to the faulty input instead of sweeping the whole field.
Commercial and industrial rooftops
Wall-mounted string monitoring boxes give factory and warehouse owners string visibility without a staffed control room, with alarms routed straight to the maintenance contractor.
Floating solar projects
Customisable cable entry on string monitoring boxes and LoRa wireless links cut the cable runs needed across water, where every extra metre of trunking adds cost and risk.
Plant pooling substations
Battery monitoring keeps a continuous watch on the DC banks that power protection relays, SCADA and communication panels, so backup power is proven healthy before it is needed.
SCADA and remote operations centres
Modbus RTU and Modbus TCP/IP outputs map directly into SCADA, data concentrators and monitoring platforms, letting integrators bring multiple plants into one operations view.
EPC testing and commissioning
Commissioning teams test each monitoring card against DC voltage, string values, alarm data and temperature, calibrate readings and save a report before the plant is energised.
From specification to energisation
How a Sertel string monitoring rollout reaches energisation.
It starts with the string layout. Our engineers match the number of strings per input, system voltage and fuse rating to the right combiner or string monitoring box, then choose the communication medium for each block: RS-485 where cable already runs, fibre optic for long or noisy routes, and LoRa wireless where trenching is impractical.
Before installation, each string monitoring card is connected to the SMC test software. The dashboard scores DC voltage, string values, alarm data and internal temperature, 25 percent each, and only a full 100 percent result passes. Temperature, voltage and current offsets are corrected against known references and verified with the CHECK function.
On site, integrators poll a fixed register map: per-string current, DC voltage, total current, DC power, internal and external temperature, surge protector and switch status, and communication health. SCADA points are built once and reused across every combiner, which shortens integration and makes the first month of operating data trustworthy.
Outcome: every string mapped, tested and calibrated before the plant exports its first kilowatt-hour.
Relevant products
Sertel Products for Renewable Energy
AWS Series · Environmental Monitoring Systems
Automatic Weather Station
A complete, field-ready weather monitoring system built around the T-AWS-DL-300 data logger. Integrates temperature, humidity, wind, rainfall, and solar sensors into a single IP65+ rated platform, engineered for unattended operation in remote and harsh outdoor environments.
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Weather Stations
Data Logger
An industrial-grade data acquisition unit with a 24-bit ADC, 16 analog inputs, and 8 digital I/O channels. Captures readings at up to 1000 Hz and transmits them to cloud platforms such as AWS IoT Core over 4G/LTE, Ethernet, or satellite telemetry.
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Smart PV DC Combiner & String Monitor
String Monitoring Box (SMB)
String Monitoring Box for PV DC combiner applications with per-string current monitoring, bus voltage monitoring and remote alarms.
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T-SCB-300 Series
String Combiner Box (SCB)
A configurable DC string combiner and monitoring box for solar PV arrays, combining multiple input strings with protection, isolation and intelligent field visibility.
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Renewable & Solar Solutions
String Monitoring Card (SMC)
Monitor PV string current, voltage, power and temperature through a card designed for integration into solar monitoring systems.
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LoRa RF Industrial Transceiver
Wireless Transceiver
An industrial LoRa RF gateway linking remote monitoring points to a Modbus-ready network, with local data logging.
Know moreFAQ
Questions solar owners, EPCs and integrators ask us most.
Bring every string and battery bank onto one screen.
Share your plant capacity, string layout and SCADA architecture with a Sertel application engineer. We will recommend the right combination of combiner, monitoring and communication hardware and support your team through configuration and commissioning.