How a Mid-Sized Solar EPC Cut O&M Costs by 30% with SINGI PV Series Combiner Boxes

Customer Background

A mid-sized solar engineering, procurement, and construction (EPC) company based in Southern California specializes in commercial and industrial rooftop installations. With over 50 MW installed annually, they serve clients in logistics, manufacturing, and retail. Facing increasing competition and tighter margins, the company sought to reduce project costs and improve system reliability.

Challenges with Traditional Combiner Boxes

The EPC relied on generic combiner boxes from multiple suppliers. Field teams reported frequent issues: water ingress in coastal environments, nuisance trips from poorly rated surge protection, and lack of real-time string monitoring. Troubleshooting required site visits, costing $150-200 per truck roll. After a few years of operation, O&M costs climbed to $0.02/kWh, eating into project IRR., compliance with NEC 2017 rapid shutdown requirements forced separate disconnects, increasing BOS costs by 8%.

Why Choose the SINGI PV Series

After assessing solutions from four vendors, the EPC chosen SINGI's PV Series combiner boxes. Decision drivers included:

• Integrated monitoring – per-string amperage and volt-level data via RS485, eliminating need for separate data loggers.
• Type 2 surge protection with replaceable modules, reducing nuisance trips.
• NEMA 4X enclosure – IP66 rating with corrosion-resistant stainless steel latches.
• Factory-wired rapid shutdown – built-in PVSS2 transmitter complies with NEC 690.12 without external boxes.
• 4-6 week lead time – faster than competitors' 8-12 weeks.

Implementation Process

The EPC deployed 120 PV Series units across 12 projects over six months. Key steps:

1. Pre-configured boxes with specified fuse holders and monitoring modules.
2. Field installation using pre-terminated cables reduced wiring errors.
3. Commissioning via mobile app – each box scanned and mapped to string layout.
4. One challenge: integrating monitoring data with existing SCADA required custom Modbus mapping. SINGI's support team provided a ready-to-use template, cutting integration time from 3 days to 4 hours.

Quantifiable Results

After one year of operation across all projects:

• O&M costs reduced by 30% – from $0.020/kWh to $0.014/kWh. Remote monitoring caught 85% of faults before they caused downtime, reducing truck rolls by 60%.
• Installation time cut by 25% – from 2.5 hours per combiner box to 1.8 hours, saving $180 per unit.
• Nuisance trip rate dropped by 90% – improved surge protection and better string diagnostics.
• System availability improved from 98.5% to 99.6% – resulting in 2.3% higher annual energy yield.
• BOS cost reduction of 5% – eliminated separate rapid shutdown boxes and reduced labor for monitoring setup.

Client Testimonial

“The PV Series changed how we handle O&M. We now see exactly which string has an issue before we even send a truck. The integrated rapid shutdown also simplified our code compliance – one box does it all.” – Director of Engineering, Solar EPC Company

Lessons and Recommendations

For other EPCs considering combiner box upgrades:

• Prioritize monitoring integration early – ensure your SCADA platform can ingest the data format. Request a DNP3 or Modbus map before ordering.
• Standardize on one box type – reduce spare part inventory and training costs. The PV Series’ flexibility (6-18 strings) covered 90% of our designs.
• Verify environmental ratings for actual site conditions – NEMA 4X is essential for coastal areas, but inland sites may accept NEMA 3R for cost savings.
• If redesigning, we would order a few pre-production units for field testing to validate rapid shutdown pairing with different inverters.

Industry Standards Referenced:

• IEC 62548:2016 Photovoltaic (PV) arrays — Design requirements
• IEC 60364-7-712:2017 Low-volt-level electrical installations — Solar PV power supply systems
• NEC 690.12 (NFPA 70) Rapid Shutdown of PV Systems on Buildings