Commissioning a Solar PV System
You may have got a solar PV system installed on your rooftop, complete with connection to the grid and a battery pack. However, before you switch it on for the first time, it’s essential to inspect its several elements thoroughly.
Doing so will not only verify the integrity of the system design and installation, but also ensure that nothing untoward happens when you press the “ON” button for the first time.
Part 1: Inspection
A) Mechanical elements: Do a detailed inspection of all of the mechanical elements of your PV system, including:
1) Racking: Check if the modules are securely connected to the racking system (also called “mounting structure”), if they are properly grounded and if the structure itself is securely attached to the footing system.
2) Footing: These are the structures that keep the racking in place, whether on the ground or on a rooftop. Check, if their location is as per design, and if the correcting hardware has been used for the systems. Also, in case of a rooftop system, the footing must ensure that no water seeps inside the building.
3) PV Modules: Check for defects across individual solar cells (which may indicate faulty cells), defects in welding of conducting strips, the overall alignment of the modules with each other and their orientation with respect to the orientation specified in the system design. You can see 2 examples of faulty cells in the below images.
B) Electrical Elements:
1) PV Modules: It’s best if you have the line drawings available and are familiar with its terminologies. However, even if you aren’t, visually check for the correct number of modules installed.
2) Batteries: Check for adequate ventilation, the integrity of their enclosure and their correct wiring. Correct wiring is extremely important, failing which, there may be serious damage to the batteries or even an explosion.
3) Charge Controllers: Check for proper location (they are usually mounted very close to the inverter and/or the battery bank), the presence of disconnects and overcurrent protection devices (OCPDs) on both the input and output sides and for the correct wire gauges.
4) Inverters: If your system is connected to the grid, does the inverter’s output voltage match the grid voltage? Also, check for proper access and cooling measures (installed in an open, shaded location with adequate airflow available to dissipate heat). It’s also essential that you check if its input voltage range matches that of the modules’ output.
5) Conductors and Conduits: Check for the integrity of the conductors (insulation, breakage etc.) and if the right gauge/size has been used (as specified in system design). Also check for colour coding (grounded wire – gray, white or green; ungrounded wire – any other colour, preferably red)
For conduits (PVC or metal pipes that carry the conductors), check that they cover the conductors properly, that the correct support structures have been used (details of which are available in local installation codes) and that expansion fittings have been used where required (as conduits can expand under sunlight).
Part 2 of this post will cover the commissioning process.