System Testing and Commissioning SS1 Solar Photovoltaic Installation & Maintenance Lesson Note

Why do we Test and Commission?

Imagine you finish building a car. You wouldn’t just give the keys to a driver without checking if the brakes work or if the engine has oil.

In solar, testing is for:

1. Safety: To make sure no one gets shocked and nothing catches fire.
2. Performance: To make sure the customer is actually getting the power they paid for.
3. Warranty: Most companies won’t replace a part unless you can prove you tested it properly when you installed it.

The Golden Rule: Always test before you put the final covers on the wires. It is easier to fix a loose screw now than when it starts smoking later!

The “Dead” Tests (Power is OFF)

We call these “Dead” tests because we do them before we turn the system on. We want to check the “roads” (wires) are clear.

1. Visual Inspection: Use your eyes! Are any wires touching metal? Are all the screws tight? Is there any “rubbish” like metal filings inside the inverter box?
2. Continuity Test: Using your multimeter, check that the wire on the roof is the same wire that reaches the controller.
3. Polarity Check: This is the most important test. Ensure that Positive (+) is actually connected to Positive (+). If you mix these up, you will see a big “Pop” and smoke when you turn it on.

The “Live” Tests (The Power is ON)

Now, we turn on the switches one by one and use our meters to see what is happening.

1. Open Circuit Voltage (Voc): Measure the voltage coming from the panels before they are connected to the controller. If the panel says 40V and your meter shows 40V, the panel is healthy.
2. Battery Voltage: Check the battery. A healthy 12V battery should show about 12.6V when full and not charging. If it shows 10V, it is too low and needs help.
3. Charging Current: Once you connect the panels, check the Amps. If it is a sunny day and your panels are 10A but your meter shows only 1A, something is wrong—maybe a wire is loose or a panel is shaded.

Performance Checks (Is it doing its job?)

After the system is running, we do a “Stress Test.” This is like asking a weightlifter to lift a heavy bar to see if he is truly strong.

1. Load Test: Turn on the fans, the TV, and the bulbs all at once. Watch the inverter. Does it make a loud “struggling” noise? Does the voltage drop too low? A good system should handle the load smoothly.
2. Inverter Output: Use your multimeter on the AC side. In Nigeria, it should be between 220V and 230V. If it is much lower, your appliances might not work properly.
3. Temperature Check: After 30 minutes of working, touch the wires (on the plastic part!). They should be cool. If a wire feels hot like a cup of tea, it is too thin and must be changed immediately!

Handover and Summary

The final part of commissioning is talking to the user. You must teach them how to “read” their system.

The “User Manual” Talk:

• Show the customer the “Charging” light.
• Explain what a “Low Battery” alarm sounds like.
• Tell them: “If you see a Red Light, turn it off and call me!”

Summary Table for the Logbook:

Class Practical A ctivity

1. The “Fake Fault” Game: The teacher should purposely leave a screw slightly loose or put a shadow on a panel. The students must use their meters to find the problem.
2. Fill the Form: Give students a blank paper and ask them to write down the “Test Results” for a 12V system they just “installed.”

The Customer Talk: One student plays the “Installer,” and another plays the “House Owner.” The installer must explain how to know if the battery is full.