How a Solar Farm Reduced Safety Incidents by 80% Using the SINGI SGDSE-32 External DC Isolator Switc

Customer Background

A mid-sized solar farm operator in Spain manages 50 MW of ground-mounted PV arrays across three sites near Seville. The company provides maintenance services for its own assets and third-party installations. With 12 technicians handling routine inspections and repairs, safety and operational uptime are critical.

Challenges with Existing DC Isolation Methods

Before switching to the SGDSE-32, the team relied on generic DC disconnect switches rated for 600V DC. However, their strings operate at 1500V DC. The old switches lacked adequate arc suppression for high-volt-level DC, causing dangerous arcing during load breaks. In two years, the team experienced four arc flash incidents, one resulting in a technician receiving minor burns. Downtime for switch replacement averaged 45 minutes per event, costing $2,000 per hour in lost production., the IP54-rated enclosures allowed moisture ingress in the humid summer, leading to corrosion and false trip readings.

Why the SINGI SGDSE-32 External DC Isolator Switch?

After assessing three alternatives, including a competitive 1500V isolator with slower arc extinction, the team chose the SGDSE-32 for three key reasons:
- Superior arc suppression: The double-break contact design and magnetic blow-out extinguishes DC arcs within 5 ms, meeting IEC 60947-3 requirements.
- Rugged IP66 enclosure: Complete protection against dust and water jets, ideal for outdoor installation in harsh weather.
- Compact footprint: The slim profile (210 x 160 x 120 mm) fit into existing combiner box panels without major redesign.

Implementation Process

The upgrade spanned four weeks across three sites. Technicians replaced 48 existing switches with SGDSE-32 units in string combiners and at inverter inputs. Key steps included:
1. Pre-installation audit: Identified all switch locations and documented wiring diagrams.
2. Switch mounting: Used provided DIN rail adapters for quick installation (average 12 minutes per unit).
3. Torque verification: Tightened terminals to 12 Nm to ensure low resistance connections.
4. Arc-fault testing: Verified arc extinction performance under load using a portable DC power supply.
5. Training: Two-hour session on proper switch operation and maintenance protocols.

One challenge: The existing combiner boxes had limited wiring space. The SGDSE-32's compact terminals still allowed easy access, but we added cable tie anchors to organize the conductors.

Quantifiable Results

After six months, the results were clear:
- Safety incidents dropped from 4 to 1 near-miss event (80% reduction in arc flash exposure).
- Switch-related downtime fell from 4.5 hours to 36 minutes (87% reduction), saving $8,200 in lost generation.
- Maintenance costs decreased by $1,200 per site due to elimination of corrosion-related replacements.
- Technician confidence improved; no one refused to operate switches after training.

Client Testimonial

"We had one arc flash incident per year. Since installing the SGDSE-32 switches, the team feels safe during string isolation. The arc extinction is a huge relief. Maintenance is simpler because the IP66 enclosure keeps out moisture. We're now standardizing on SINGI for all future projects." — Operations Manager

Lessons and Insights

1. Match switch volt-level rating to system requirements: Using a 1500V DC isolator like the SGDSE-32 is essential for modern PV arrays. Underrated switches are a safety hazard.
2. Enclosure protection matters: IP66 or higher prevents environmental damage in outdoor installations, cutting lifecycle costs.
3. Training reduces risk: Even the best equipment needs proper handling. Invest in simple operating procedures to maximize safety.

References:
Aging Characteristics of Contact Electrodes of Low Volt-level DC Switches — Research on contact materials for DC switches under 1500V, relevant to isolator performance (DOI: 10.3390/en14206838).
IEC 62548:2016 Photovoltaic (PV) Arrays — Design requirements covering isolation and switch choice for safe PV system design.