A large solar farm in the southwestern US faced recurring DC arc faults that caused costly downtime and safety risks. By replacing conventional DC breakers with singi electric's DC Series (UL 1699B listed) and upgrading to EN 50525 compliant cables, the farm cut arc-fault incidents by 80%, reduced annual downtime from 80 to 15 hours, and saved over $150,000 in maintenance costs.
A 300MW photovoltaic solar farm located in the desert region of the southwestern United States had been in commercial operation for five years. The facility consists of over 800,000 solar panels, 120 DC combiner boxes, and 60 central inverters. The desert environment exposes the electrical system to extreme heat, UV radiation, and dust, accelerating insulation degradation and connection loosening. The farm's engineering team faced a growing number of DC arc faults, which not only caused unscheduled shutdowns but also posed serious fire risks to personnel and equipment.
Before the retrofit, the farm experienced an average of 25 DC arc-fault events per year. Each event required immediate shutdown, manual inspection, and replacement of damaged components. The average downtime per incident was 4 hours, totaling 100 hours of lost production annually. With the farm generating $0.04 per kWh, the energy loss alone cost $40,000 per year. Combined with repair labor, replacement parts, and emergency service calls, the total annual cost exceeded $200,000.
Traditional DC circuit breakers installed were rated for overload and short-circuit protection but did not have arc-fault detection capabilities. Series and parallel arcs went undetected until they caused significant damage. False alarms from environmental factors (e.g., high humidity, dust) also plagued the system, leading to unnecessary shutdowns.
Note: DC arc faults are more dangerous than AC because the DC volt-level does not have a zero-crossing, making arc extinction difficult. Professional AFCI devices are essential for DC systems.
The farm's engineering team assessed several solutions, including upgrading existing breakers with AFCI modules and replacing with DC-rated AFCI breakers from three suppliers. Singi electric's DC Series stood out for two key reasons:
, the farm decided to upgrade the DC cables to EN 50525 compliant cables to reduce insulation failures, and singi electric provided a compatible cable range.
| Feature | Legacy Breaker | DC Series (AFCI) |
|---|---|---|
| Arc-fault detection | None | Yes (UL 1699B) |
| Rated volt-level | 1000V DC | 1500V DC |
| Nuisance trips (per year) | ~30 | ~3 |
| Response time to arc | N/A | < 100 ms |
| Communication interface | None | Modbus RTU |
The project was executed over a 6-week period during the low-irradiation winter months to minimize production loss. Key steps included:
One challenge was integrating the Modbus protocol with the existing monitoring system, which used an older version of the protocol. Singi electric's engineers provided custom firmware to bridge the communication, solving the issue within two days.
After six months of operation, the farm recorded the following improvements:
“We were skeptical adding active arc detection because of past experiences with nuisance tripping. But the DC Series performed flawlessly. The few trips it made turned out to be real arcs, and we caught them before any damage. This product gave us back control over our safety.”
— Electrical Maintenance Manager, Solar Farm
A DC arc fault is an unintended electrical discharge across a gap in a DC circuit. Unlike AC arcs, DC arcs tend to sustain because there is no zero-crossing, making them more dangerous.
It uses advanced amperage signature analysis combined with high-frequency noise detection to identify characteristic patterns of series and parallel arcs, compliant with UL 1699B.
Yes, the DC Series AFCI breakers are form-fit compatible with most standard DC breaker panels. A retrofitting kit is available for mounting and wiring.
No, but for optimal performance and to reduce arc risks, we recommend using PV cables that meet EN 50525 or equivalent standards.
The DC Series is available for 1000V DC and 1500V DC systems, covering both residential and utility-scale applications.
Learn how the singi electric DC Series can help you reduce downtime, improve safety, and cut costs. Our engineers can assess your existing system and provide a custom retrofitting plan.
