Commissioning, documentation and handing over to the customer

Commissioning turns an installed system into a working, documented asset. It is also the moment the customer forms their opinion of you. A tidy power-up, a clear explanation and a complete file earn referrals; a rushed "it's running, sir" followed by a confused phone call next week does not.

Before you power up

Confirm that: - All the tests in lesson 3 are done, recorded and passed. - All terminals are torqued, covers are on, glands are tight, and labels are in place. - The roof is clear of tools and offcuts. - The DISCOM status is known. If the net meter is not yet installed, check what the DISCOM allows. Some do not permit the inverter to run (or to export) before the net meter is fitted, because the old meter may record export as import or flag tampering. Follow the local rule; zero-export mode may be an option until the meter arrives.

Power-up sequence

Follow the inverter manual. A common sequence for string inverters:

1. Close the AC side first: main DB breaker, ACDB MCB. The inverter sees the grid.
2. Insert DC fuses (if any) and close the DC isolator in the DCDB.
3. Switch on the inverter's own DC switch.
4. Wait for the inverter's self-test: it measures insulation resistance, checks grid voltage and frequency, then connects after a countdown (often 30–300 seconds).

Grid code / country setting: at first start-up, many inverters ask for the country or grid standard. Select the setting required in India and by the DISCOM. A wrong setting (for example a European code) uses the wrong voltage and frequency trip limits and can cause nuisance trips or non-compliance.

Set the date, time and time zone (IST) correctly, or the monitoring data and ToD reports will be wrong.

Is it producing what it should?

Do not accept "the display shows 3.8 kW" without a reason to believe 3.8 kW is right. Calculate the expected power from conditions you measure.

Expected AC power ≈ kWp × (G ÷ 1,000) × [1 + γ × (Tc − 25)] × DC losses × inverter efficiency

• G: plane-of-array irradiance from an irradiance meter held in the plane of the modules
• Tc: module (cell) temperature from a thermometer on the back-sheet (cells run a few degrees hotter)
• γ: power temperature coefficient from the datasheet

Worked example

5.4 kWp array, irradiance 850 W/m², module temperature 55 °C, γ = −0.35 %/°C, DC losses (cable, mismatch, light soiling) about 3%, inverter efficiency 96%.

• Irradiance: 5.4 × 0.85 = 4.59 kW
• Temperature: × [1 − 0.0035 × 30] = × 0.895 → 4.11 kW
• DC losses: × 0.97 → 3.99 kW
• Inverter: × 0.96 → 3.83 kW AC expected

The inverter shows 3.75 kW: 98% of expected. That is a pass. If it showed 3.2 kW (84%), look for a string not connected, shading, a wrong string configuration or a sensor problem.

Functional and protection checks

• Anti-islanding: with the inverter exporting, open the ACDB MCB (or the main switch). The inverter must stop within about 2 seconds and show "grid lost". Close the MCB: it must wait its reconnection delay (typically a minute or more) before restarting. Record the result.
• RCCB: press the test button; it must trip.
• Emergency shutdown: walk the customer through it (below) and do it once together.
• Backup (hybrid systems): simulate an outage and confirm essential circuits stay on (module 7, lesson 5).
• Monitoring: connect the inverter to Wi-Fi or the data logger, create the customer's account on the app, and check that data arrives. Note the Wi-Fi name; when the customer changes their router password, monitoring stops.

The handover file

IEC 62446-1 lists the documentation a system should have. A practical Indian handover file, printed and as a PDF on WhatsApp or email:

1. System summary: customer, address, kWp, number and model of modules, inverter model, commissioning date, DISCOM consumer number, application ID
2. Single-line diagram and string layout (which modules form which string)
3. Datasheets for modules, inverter, SPDs, isolators, cables
4. Test results: continuity, polarity, Voc, current, insulation resistance, earth resistance, with date and conditions
5. Commissioning record: expected vs measured power, anti-islanding result, grid code set
6. Warranty documents: module product and performance warranties, inverter warranty with registration proof, structure and workmanship warranty from you
7. CMC / AMC terms: what is covered, visit frequency, response time (five years under PM Surya Ghar)
8. DISCOM documents: agreement, net-meter installation report, commissioning certificate
9. O&M guide for the customer: cleaning, what alarms mean, who to call
10. Photos: structure, anchors and waterproofing, earthing, DB wiring, serial labels

Training the customer: 15 minutes that save 15 calls

Cover, at the inverter, with the customer and whoever else will deal with the system (often a family member or caretaker):

• What normal looks like: the display, the app, roughly what a sunny day should produce (for example "about 5 units per kWp on a clear March day, so about 27 units for this 5.4 kWp system").
• Shutdown procedure: AC MCB off, then DC isolator off, and the reverse to restart. Point to the laminated card.
• Cleaning: when, how, and what not to do (module 9, lesson 5).
• What not to touch: connectors, DB internals, the net meter.
• When to call: alarm codes, zero generation on a sunny day, a burning smell, an RCCB that trips repeatedly.
• The first bill: explain how the net-metered bill will look and when the change shows (often the second billing cycle).

Key points

• Power up in the manual's order (commonly AC first, then DC), select the correct Indian grid code and set IST.
• Check output against a calculated expected value using measured irradiance and module temperature.
• Test anti-islanding, RCCBs, backup and monitoring, and record the results.
• Hand over a complete file: summary, SLD, datasheets, test results, warranties, CMC terms, DISCOM documents, O&M guide and photos.
• Train the customer on normal operation, shutdown, cleaning and when to call.

Check yourself

1. A 3.3 kWp array at 900 W/m² and 50 °C (γ −0.35 %/°C), DC losses 3%, inverter 96%. What AC power do you expect?
2. During the anti-islanding test, what should happen when you open the AC MCB?
3. Why does setting the wrong country grid code matter?