The 5-kg One-Person Kit: SC-DEL-Portable on Rooftop Inspections

Anyone who has done PV operations and maintenance knows the two "iron laws" of traditional EL inspection: first, it must be done at night — daylight drowns out the faint near-infrared emission; second, it requires a team — one to carry equipment, one to power it, one to align. These two rules made rooftop EL inspection (especially commercial-and-industrial distributed PV) effectively impractical for a decade — rooftop owners refuse night-shift access, and O&M firms hate three-person rotations. SC-DEL-Portable breaks both rules with a 5-kg one-person kit. This article unpacks the engineering trade-offs behind it.

1. How daylight EL actually works

EL is essentially the ~1100 nm near-infrared emission from a PV cell, with intensity on the order of one millionth of direct sunlight. How do you "see" that under 1000 W/m² of sun? SC-DEL-Portable stacks three techniques:

1. InGaAs sensor: a silicon camera has only ~5% sensitivity at 1100 nm; InGaAs hits ~90% in the same band — an 18× boost in baseline SNR;
2. Narrow bandpass filter: a 1100 ± 15 nm bandpass filter blocks ~95% of solar radiation at the lens;
3. Lock-in subtraction: a 1–10 Hz pulsed current is applied to the cell; the camera captures "on" and "off" frames in sync and subtracts them, leaving only EL signal. (Full math in our April 30 article on lock-in subtraction.)

Stacked together, daylight EL SNR reaches 60–70% of nighttime EL — enough to clearly see microcracks, broken fingers, and other major defects.

2. Why total weight had to be ≤5 kg

The portability "curse" is well known: above 7 kg, the operator's arm is sore after 30 min; above 10 kg, alignment becomes inaccurate within an hour. A typical rooftop survey is 4–6 hours of continuous work — total weight must stay below 5 kg for one-person operation to even be feasible.

SC-DEL-Portable's weight reduction:

Total weight saved: 3.9 kg, from an industry average of 8–9 kg down to 5 kg. The cost is ~18% higher unit BOM, but the offset is one-person feasibility — ROI works out better for customers.

3. 800-module-per-charge endurance

A common question: "If you operate during the day, why specify endurance per night?" Because SC-DEL-Portable supports both daylight EL and conventional nighttime EL, and daylight operation actually consumes ~30% more power (more frequent pulsed current + heavier differential computation). So the real metric is "modules per full-load charge cycle".

Battery: 96 Wh; per-module energy: ~0.12 Wh:

• Current injection: 0.04 Wh (8 W avg × 18 s in pulse mode)
• Imaging + algorithm: 0.06 Wh (12 W × 18 s)
• Display + Wi-Fi: 0.02 Wh (5 W × 18 s)

Theoretical: 800 modules per charge. Field-realistic with temperature, alignment delays and screen brightness: 600 modules per charge, covering a 2 MW C&I rooftop in one trip.

4. Where SC-DEL-Portable fits

Three scenarios where SC-DEL-Portable wins on economics:

1. C&I rooftops (100 kW – 5 MW): owners work daytime hours and refuse night access; one-person, 4–6 h, full coverage;
2. Mountainous / small-scale PV: complex terrain blocks drone operation; the operator climbs in with the kit;
3. EPC handover / insurance audit: third-party agents need quick, independent, visual reports — fewer logistics on site.

5. Versus competitors

The differentiator is doing all three at once: solo operation, daylight imaging, and high detection rate.

6. Where it isn't the right fit

SC-DEL-Portable isn't universal:

• Utility-scale ground-mount (>10 MW): walking inspection is too slow — use SC-DEL-Drone;
• PID / LID degradation analysis: needs IV co-measurement — use SC-IV-Portable;
• Extreme heat (>45 °C): prefer night operation — use the standard SC-EL-Portable kit.

For demos or a rooftop-inspection assessment, contact MVCreate at +86 159-5048-9233.

Originally published by Vision Potential (Nanjing MVCreate Intelligent Technology Co., Ltd.). Reproductions must credit the source.