Guides · Faisalabad, Lahore, Punjab
How We Test and Commission a Solar System
Short answer
Solar commissioning is the set of tests and checks done after installation and before a system is switched on for normal use and handed over. It proves that the wiring is correct and safe, that protection works, and that the inverter, battery and monitoring are set up for your site. At Solar Works Pakistan, all the tests and checks needed for safe commissioning are completed before handover, by our own engineering staff.
This article explains what we test and why, in the order the work is done. If you want a checklist to inspect any installation yourself, use our workmanship checklist; this page is the engineer's side of the same story.
Safety note. Commissioning tests involve live DC strings and test instruments that apply high voltage. They must only be done by trained staff with proper instruments and PPE. Please do not attempt them yourself.
Why commissioning is more than "switching it on"
An inverter will often start and show output even when something is wrong. A reversed string, a weak connector, a missing earth bond or a wrong grid setting may not stop the system on day one. They show up later as faults after rain, nuisance trips, hot joints, lower output or, at worst, a safety hazard.
Commissioning finds these problems while the installation team is still on site and before the roof is closed up. It also creates a baseline: a record of what the system measured on the day it was handed over, which makes later faults easier to trace.
International guidance follows the same logic. IEC 62446-1, the international standard on testing and documenting grid-connected PV systems, groups basic safety tests (earth continuity, polarity, string voltage and current, functional tests and insulation resistance) ahead of optional performance tests such as I-V curve tracing and thermal imaging. We use it here to explain what each test is for; it is not a certification claim.
Commissioning tests
DC side
String voltage and polarity
AC side
Breakers, earthing and protection
Handover
Settings, app and serial list
Stage 1: visual inspection before anything is energised
Before any test instrument is connected, the engineer walks the installation:
- structure fixings, clamps and bracing as designed (see how we design structures);
- cable routes clipped, protected and in conduit where needed;
- MC4 connectors fully locked and matched (see MC4 connectors and earthing);
- DC isolators, breakers, surge protection devices and the distribution board as per the design;
- inverter and battery positions with the clearances their manuals require;
- labels in place.
Anything that does not match the design is corrected first. This is one reason we design in-house: the commissioning engineer checks the work against the same drawings the team built from.
Stage 2: DC-side electrical tests
These tests are done with the strings isolated from the inverter.
| Test | What it checks | Why it matters |
|---|---|---|
| Earth continuity | Panel frames, structure and equipment are bonded to earth | A missing bond can leave metal live during a fault |
| Polarity | Positive and negative are correct on every string | Reversed polarity can damage the inverter or protection devices |
| String open-circuit voltage | Each string's voltage against the design value | Shows a missing panel, wrong panel count or bad connection |
| String current | Each string delivers current consistent with the sunlight at the time | Shows shading, damaged panels or poor connections |
| Insulation resistance | No leakage path from the DC cables to earth | Catches damaged cable insulation and wet connectors before they cause faults |
Polarity is always checked before strings are connected together, because a reversed string can do damage the moment it is joined. Voltage and current are compared across strings of the same design: strings that should match but do not point straight to the problem. Our guide to series and parallel wiring explains why matching strings matters.
Insulation resistance is the test buyers rarely hear about and the one that prevents many "insulation fault after rain" calls later. The pass value depends on the system voltage and the test method.
Stage 3: AC side, earthing and protection
- AC circuit checks on the inverter output cable, breakers and the connection to the distribution board.
- Earth resistance of the earth pit or earthing system, and continuity to the surge protection devices. Our earthing and surge protection guide explains why an SPD is only as good as its earth.
- Breaker and isolator ratings checked against the design, including DC-rated devices on the DC side. See MCB, MCCB and RCCB explained.
- Terminal tightness in the board and at the inverter.
Stage 4: inverter, battery and grid settings
Before the inverter is allowed to export or carry loads, its settings are checked against the site and the equipment:
- Grid settings for Pakistan's voltage and frequency, so the inverter connects and disconnects correctly.
- Export limit or zero-export settings where the design calls for them.
- Battery type, voltage and charge limits, and communication between the battery's BMS and the inverter. Our guide to the battery management system explains why the two must talk to each other.
- Operating mode (for example solar first, battery priority or grid charging), set to match how you will use the system.
- Time, date and site details so monitoring data is correct.
Stage 5: functional tests
Now the system is switched on in stages and its behaviour is tested.
- Start-up: the inverter connects, and output rises in line with the sunlight.
- Isolator and breaker operation: each one switches as expected.
- Grid-loss test: with the grid disconnected, an on-grid inverter must stop feeding the line. Our explainer on anti-islanding covers why.
- Backup changeover on hybrid systems: essential loads transfer to battery when the grid goes, and return when it comes back.
- Generator integration, where fitted: the controller limits solar so the generator stays above its minimum load and never receives power back. See our hybrid generator engineering article.
- Monitoring: the Wi-Fi dongle or data logger reports to the app, and readings match the inverter display. See our monitoring app guide.
Optional performance tests on larger systems
On larger commercial and industrial plants, two further tests can be useful:
- I-V curve tracing, which draws each string's full current-voltage curve and shows defects that a simple voltage reading misses.
- Thermal imaging, which shows hot spots in panels, connectors and boards under load.
Both need good, steady sunlight to give meaningful results.
Handover: what you receive
After commissioning, we train you on the system: how to operate it, how to read the inverter, how to use the monitoring app and what the normal status looks like. You receive the relevant project documentation. Manufacturer warranties for panels, inverters and batteries are.
After handover, our structures carry a 3-year structure warranty, and our 1-year service warranty (including breaker replacement) applies under the applicable project terms. Our own engineering staff handle after-sales support, with a 48-hour target to send personnel after a complaint is registered. See how after-sales service works, and for the weeks after handover, your first 30 days with a new solar system. A year later, our guide to comparing actual output with the estimate helps you check performance.
Get today's price or a free site survey
Want a system that is tested properly before it is handed over? Talk to our engineers.
- WhatsApp or call: 0336 666 4321
- Email: info@solarworks.pk
- Head office: Main Boulevard, Sargodha Rd, Block F FDA City, Faisalabad
- Lahore branch: 2nd Floor, Jeff Heights, Gulberg, Lahore
- Hours: 9:00 AM to 6:00 PM, daily
We serve customers throughout Punjab, from about 6 kW to megawatt-scale industrial and commercial projects, and site surveys are normally free. See our solar installation services, our Faisalabad and Lahore pages, or contact us.
Frequently asked questions
What is solar commissioning?
It is the testing and setup done after installation and before handover: visual inspection, DC and AC electrical tests, protection checks, inverter and battery settings, and functional tests such as grid-loss and backup changeover. It proves the system is safe and working as designed.
What is an insulation resistance test on a solar system?
It checks that there is no leakage path from the DC cables and panels to earth. It finds damaged insulation or wet connectors before they cause "insulation fault" errors or a safety risk. It uses a dedicated tester and must be done by trained staff.
Why does the inverter need to be set up during commissioning?
The inverter must be set for the local grid, the battery type and limits, any export limit and your preferred operating mode. Wrong settings can cause trips, poor battery life or behaviour you did not expect.
How long does commissioning take?
It depends on the system's size and complexity. A home system takes much less time than a factory plant with several inverters, a generator controller or battery storage. Commissioning is completed before handover, not rushed to meet a date.
Can I test my own solar system?
You can watch the monitoring app and the inverter display, and look for visible problems from a safe position. The electrical tests themselves involve high DC voltage and special instruments, so leave them to trained staff.
Do you commission systems installed by other companies?
Contact us with the details. We need to see the design, the equipment and the site before we can say what testing and correction would be involved.
Sources
- Fluke and pv magazine, PV commissioning and IEC 62446-1 testing guide (May 2024), used for the grouping and order of basic and performance tests