A commercial and industrial rooftop solar EPC based in Vietnam replaced its conventional DC cabling with Singi Electric Solar System Cable across a 38 MWp portfolio. Within one year, the contractor reduced cable-related commissioning defects by 61%, cut on-site installation time by 22%, and saved an average of $41,000 per project campaign in rework and warranty costs.
The customer is a solar engineering, procurement, and construction company headquartered in Binh Duong Province, Vietnam. Over four years, it delivered more than 60 rooftop PV installations across Vietnam, Thailand, and Cambodia, totaling roughly 38 MWp. The company employed 24 engineers and 60 field technicians, and most projects were C&I rooftops with capacities between 500 kWp and 3 MWp.
The EPC won contracts on speed and price, which forced procurement to chase lower component costs. However, thin margins left no room for sustained repair work. Investors in these projects now demand harsh performance guarantees, and the EPC’s internal quality team was spending increasing effort on post-commissioning callouts and generation losses during fault events.
The contractor used a mix of imported PV1-F cable and a generic multi-core DC cable across its earlier sites. After the first rainy seasons, site inspection reports showed cracked outer jackets, loose gland connections, and visible corrosion at terminations. On a 1.2 MWp rooftop in Long An Province, ground-fault alarms took an inverter string offline four times in a single week. Each event required a full site visit, disconnection of the string, and thermal scanning of thousands of feet of cable.
Another recurring problem appeared when installers terminated cable at string combiner boxes. The cable’s soft copper strands sometimes broke during crimping, creating high-resistance joints. These joints later showed up as hot spots on thermal imaging audits, and the EPC had to replace several connectors after only 18 months of service.
The financial impact was substantial. Rework and extended commissioning schedules cost an average of $38,000 per 2 MWp site in technician overtime, replacement material, and compensation for delayed commercial operation dates. Project completion was delayed by a median of eight days, and the contractor was losing repeat customers because of poor commissioning experiences.
Procurement had attempted to reduce costs by switching to a lower-priced cable from a regional supplier. Laboratory samples of that cable failed the heat-aging portion of the EN 50618 / IEC 62930 test after 500 hours, due to excessive insulation shrinkage. The company cancelled the purchase and returned to the previous supplier, but over the following year the failure rate stayed near 12% of all field terminations.
The engineering team prepared a new cable specification based on the IEC 62930 / EN 50618 standard for photovoltaic system cables. The assessment criteria included conductor construction, temperature rating, UV and ozone resistance, halogen-free behavior, flame retardance, and continuous batch traceability marking on the jacket.
Singi Electric was chosen over three other suppliers for two main reasons. First, the Singi Electric Solar System Cable used a tinned stranded copper conductor, which eliminated the galvanic corrosion concerns seen with aluminum or bare copper terminations. Second, its H1Z2Z2-K-style jacket remained flexible at ambient temperatures above 45°C, which made pulling through rooftop cable trays noticeably faster.
The EPC also valued Singi’s engineering support. Singi provided an ampacity and volt-level-drop calculation file built the actual string volt-level and conductor lengths, than offering a generic choice chart. That let the project manager eliminate at least two conductor gauge sizes that had been over-specified.
The rollout was completed over six months across eight active projects. The plan followed four steps.
The most difficult point came during the retrofit of one older site where the string combiner boxes used an unusual OEM connector. The Singi cable could not be terminated without an adapter, and conventional adapters introduced additional resistance and failure points. Singi’s technical team resolved this by supplying pre-stripped and pre-crimped cable ends with a specified MC4-compatible connector body, which matched the existing connector system without custom splices.
The contractor compared construction quality logs from the six-month period before the rollout with the first eight projects after completion of the rollout.
The cumulative effect was a measurable improvement in the EPC’s project margin, because the savings did not come from a lower purchase price but from reducing the hidden cost of failures. The contractor also saw a visible boost in client confidence after three consecutive projects reached commercial operation without cable-related penalties.
“The change was visible from the very first site: no boot replacement, no heat-shrink patches, no last-minute re-runs,” said the EPC’s project director. “Specifying one Singi Electric Solar System Cable across all runs kept the commissioning team focused on clean terminations. Not a single string-level cable fault has appeared since the third installation.”
Three practical takeaways emerged from this project.
If the EPC were to repeat the exercise, the project director noted that they would replace the cable type on existing operational projects before the rainy season than after. The higher upfront replacement cost would be offset by fewer emergency outages during storm conditions in Southeast Asia.
The successful project is a clear example of the operational impact that thoughtful solar system cable choice can make. While cable is only one part of a PV plant, it is the component that connects every energy-producing asset, and a failure at any point can shut down a complete inverter string. The standards that governed this installation are IEC 62930:2017 for photovoltaic system cables and IEC 60364-7-712:2017 for solar PV power supply installations. These references define the construction, testing, and installation requirements that ensured reliable performance for this EPC’s entire 38 MWp portfolio.
