AE 868
Commercial Solar Electric Systems

Commissioning Procedure

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After the installation of any PV system is completed and the inspection is done, the system will be ready to be plugged to the grid to transfer energy. That process is referred to as Commissioning the system. At the same time, the installer will hand the responsibilities to the owner or operator of the system.

There are steps and requirements to commissioning PV systems that vary depending on system size and complexity of design. However, there are general guidelines that apply to most systems.

Final checkout

The system should be checked thoroughly before the commissioning starts.

A highlight of the main electrical items to consider:

  • All disconnects are in (OFF) position during the final checkout.

  • Installation matches the design documentation.

  • Conductors, OCPD, and disconnect are sized appropriately.

  • Compliance with all local AHJ and national codes (including NEC) is met.

  • Terminals connections and screws are securely tightened. 


A highlight of the main mechanical and structural items to consider:

  • Equipment is securely mounted (such as modules, racking, inverters, panels and disconnects and so on)  

  • Roof penetrations are properly weather sealed

  • Installations are matched to the manufacturer's specifications and recommendations. 


Other safety items to consider:

  • Applicable warning signs and labels are posted appropriately

  • The job site is clean and orderly

  • The documentation package is complete

  • Attention has been paid to details such as removing tools from the site before commissioning


Commissioning Procedure

When intending to start the PV system the first time, the procedure starts at the array and ends at the point of connection. This will reduce hazards and make the diagnostic and testing of subsystems easier in case there is a problem in the installation.

Reading

PV commissioning is a procedure that requires a lot of attention to details. Solar professionals are encouraged to refer to the required reading "PV System Commissioning" available on the overview page of this lesson.

1: Connect power sources to systems (this includes connecting PV module wire runs)

  • Considerations
    • AC and DC disconnects need to remain in “OFF” position 

    • Fuses are not connected

2: Test DC voltage and polarity

  • Make sure to use proper meter settings for DC

  • Test after connecting PV modules in series and measure

  • Expected voltage (from calculation of modules)

  • Voltage polarity

     
  • Considerations
    • AC and DC disconnects need to remain in “OFF” position

    • Fuses not connected as well

    • Watch for negative sign on meter that means lead positions of meter is not correct or circuit is not wired properly!!!


3: Test AC voltage at inverter output

  • Make sure to use proper meter settings for AC

  • Test Line to Line and Line to Neutral 

  • Compare with inverter AC voltage (specs sheet)
  • If inverter has settings for more than one connection, match your service setting for voltage

  • After this step, return fuses if applicable

4: Start-up procedure

  • Lift AC disconnect lever (inverter to grid)

  • Lift DC disconnect lever (PV to inverter) 

     
  • Considerations
    • Check with manufacturer’s manual for specific startup procedure 

    • Most inverters have Delay to check on grid and synchronize before connecting