Rooftop Solar Commissioning Checklist for Installers

Short answer: commissioning a rooftop system means proving it is safe, built as designed and documented. Walk through mechanical checks, then DC tests (polarity, string Voc and current, insulation resistance), earthing tests, AC and protection checks, inverter settings and anti-islanding, then the DISCOM inspection, portal uploads and customer handover. IEC 62446-1 is the reference for tests and records.

Before you start

• [ ] Approved drawings: layout, SLD, string plan
• [ ] Calibrated instruments: multimeter, clamp meter (DC), insulation tester, earth tester, irradiance meter (if available)
• [ ] PPE: insulated gloves, safety shoes, harness for roof edges
• [ ] All DC isolators OFF; AC isolator OFF and locked; warning signs in place

1. Mechanical and visual

• [ ] Structure as per design; bolts torqued and marked
• [ ] Anchors set and sealed; no slab cracks; drains clear
• [ ] Module clamps in the manufacturer's clamp zones; no damaged glass or frames
• [ ] Setbacks and walkways kept; no new shade sources
• [ ] DC cables in UV conduit or covered tray; no cables on sharp edges; drip loops at entries
• [ ] MC4 connectors fully mated, same make on both halves; no strain
• [ ] Lightning down conductor routed separately from PV cables, clamped, with test joint
• [ ] Ferrules and labels on every string, DCDB, ACDB and isolator
• [ ] DCDB and ACDB glands tight, IP rating maintained

2. Earthing

• [ ] Every module frame and structure section bonded
• [ ] DC, AC and LA pits completed with inspection chambers
• [ ] Earth resistance of each pit measured and recorded (follow the project or DISCOM specification; IS/IEC 62305-3 suggests 10 Ω or less for the lightning earth-termination system where possible)
• [ ] Protective earth continuity from frames to pit, and from inverter and ACDB to pit
• [ ] Interconnection scheme as per design (see earthing and lightning)

3. DC tests (per string, before connecting the inverter)

A string reading one module's Voc low usually means a reversed or missing module connection; a very low reading may mean a failed bypass diode or a damaged cable.

Expected cold Voc must stay below the inverter's maximum input voltage. See string sizing.

4. AC side and protection

• [ ] AC cable size and route as designed; voltage drop within target
• [ ] MCB/MCCB rating ≥ 1.25 × inverter current and ≤ cable ampacity
• [ ] RCCB type and sensitivity as per inverter manual (Type A, or Type B where required)
• [ ] AC SPD fitted; Uc suitable (around 320 V on Indian feeders)
• [ ] Isolator at the meter end accessible for DISCOM lock-out
• [ ] Phase and neutral correct; phase sequence correct on three-phase
• [ ] Grid voltage and frequency measured at the inverter terminals

5. Inverter setup

• [ ] Country or grid code set for India as required by the DISCOM; voltage and frequency trip limits not altered beyond permitted values
• [ ] Inverter certification documents available (BIS registration and anti-islanding test report)
• [ ] Power factor and export settings as per DISCOM requirements
• [ ] Monitoring connected (Wi-Fi or GSM); customer account created
• [ ] Time and date correct

6. Energise and verify

1. Close the AC isolator and MCB.
2. Close DC isolators one MPPT at a time.
3. Confirm the inverter synchronises and starts exporting.
4. Check each MPPT voltage and current on the display against expectations.
5. Anti-islanding check: open the AC isolator and confirm the inverter stops within its specified time. Restore.
6. Note the initial generation, irradiance and time.

7. Documentation and photos

• [ ] Final SLD and layout (as built)
• [ ] Module serial list, DCR certificate (for subsidy) and invoice
• [ ] Inverter serial and warranty registration
• [ ] Test report: Voc, Isc, insulation, earth resistance, AC readings
• [ ] Photos: array, nameplate, DCDB, ACDB, earthing pits, LA, inverter
• [ ] PM Surya Ghar portal uploads, where applicable

8. DISCOM inspection and net meter

• [ ] Net meter tested and sealed (often supplied or tested by the DISCOM)
• [ ] Generation meter fitted where the state or category requires it
• [ ] Inspection attended; commissioning report recorded on the portal

9. Customer handover

• [ ] Explain start-up and shutdown sequence
• [ ] Show how to read the inverter and app
• [ ] Explain cleaning (soft water, early morning) and safety (never open MC4 under load)
• [ ] Explain the first net-metered bill
• [ ] Give the maintenance schedule and contact; book the first service visit

Share our cleaning and maintenance guide with the customer.

Common reasons systems fail inspection

• Missing or unreadable labels and danger signs
• SLD not matching what is installed
• SPD missing or wrong voltage rating
• Earth resistance not measured or not recorded
• Module serial numbers or DCR papers not matching the invoice

Fix these before you call the DISCOM, not after.

Keep a copy for yourself

Store the test report, photos and serial lists in the customer's job folder. They make warranty claims, future service and any DISCOM query far easier.

Talk to Sunlectric

Need a spare SPD, MC4 tool, earth-test reading help or a replacement module on commissioning day? WhatsApp +91 89567 89307 (wa.me/918956789307); our Pune hub dispatches the same day for orders before 2 pm, and our RMA desk handles warranty claims on material bought from us. The Academy installation module covers testing step by step.

Sources

• IEC 62446-1 Photovoltaic systems: requirements for testing, documentation and maintenance (check current edition)
• IS/IEC 62305-3 lightning earth-termination guidance: Furse technical guide, p. 278 (accessed 20 Oct 2026)
• CEA (Technical Standards for Connectivity of Distributed Generation Resources) Regulations and CEA safety regulations (check current editions)
• Sunlectric Studio rules (breaker factor, SPD Uc, RCCB guidance), Oct 2026