Mock Installation Project II – SS3 Solar Photovoltaic Installation & Maintenance Lesson Note (Second Term)

Installing a solar photovoltaic system means mounting the inverter and charge controller, connecting the parts in the correct order, then testing the system before handing it over. The order is battery to controller, panels to controller, inverter to battery, then load to inverter. Commissioning is the final live test, followed by customer handover and a logbook entry.

• Class: SS3
• Subject: Solar Photovoltaic Installation and Maintenance
• Topic: The Physical Installation and Final “Switch-On” (Commissioning)

Behavioural objectives

By the end of the lesson, students should be able to:

1. State the safety rules to follow during a mock installation.
2. Mount the inverter and charge controller correctly on a wall.
3. Connect the system components in the correct wiring sequence.
4. Carry out the commissioning checks: the sniff test, voltage verification and polarity check.
5. Hand over the system to the customer and complete the logbook.

What is a mock installation project?

A mock installation is a practice installation done in class, in which a group fits and tests a small solar system as if for a real customer.

• Link to the last lesson: the design and sizing are finished, so this lesson turns the plan into a working system.
• Purpose: it prepares you for the SSCE practical.
• Why it matters: a good design is of no use if the installation is untidy or unsafe.

What is the professional mindset?

• Part electrician: you connect cables, fuses and terminals correctly.
• Part carpenter: you drill, fix and mount equipment firmly.
• Part scientist: you measure, test and record results.
• Precision: a half-driven screw or a wire stripped too long can cause a failure the following week.

What safety rules apply during a mock installation?

Safety rules are the habits that protect people and equipment while the system is being fitted.

• Dry hands: wet hands raise the risk of shock and make tools slip.
• Eyes up: watch where teammates are moving, especially when carrying batteries or glass panels.
• No metal jewellery: rings and bracelets can touch battery terminals and cause a short circuit.
• Insulated tools: keep spanners and screwdrivers away from both battery terminals at once.
• Protective wear: use gloves and safety goggles where available.
• Lift with care: batteries are heavy, so lift with a partner and bend the knees.
• Panels make power in light: cover them with a cloth or keep the panel switch off while wiring.

What tools and materials are needed?

Gather everything before you start, so the work is not interrupted.

How do you mount the inverter and charge controller?

Mounting means fixing the inverter and charge controller firmly on a suitable wall, with space around them for air.

1. Choose the wall: pick a cool, dry wall. Inverters get hot when they work, so they need “breathing space” (ventilation) around them.
2. Mark the holes: hold the equipment against the wall, level it and mark the screw positions with a pencil.
3. Drill and plug: drill the holes and insert the correct wall plugs.
4. Fix firmly: use the correct screws. These components are heavy, and they must not fall off the wall at night.
5. Apply the eye-level rule: install the charge controller at eye level, so you can read its screen and check that the system is charging.

What is the correct wiring sequence?

The wiring sequence is the order of connection: battery to controller, panels to controller, inverter to battery, then load to inverter.

A wrong order can burn (“fry”) an expensive charge controller. Follow the golden sequence:

1. Battery to controller: this wakes up the controller and tells it whether the system is 12V or 24V.
2. Panels to controller: connect the sun’s power only after the controller is “awake”.
3. Inverter to battery: connect the inverter directly to the battery terminals, with a fuse or breaker as designed. The inverter draws too much power for the controller to handle.
4. Load to inverter: finally, plug in the bulbs or fans.

What is commissioning?

Commissioning is the final live testing of a newly installed system to prove that it works safely.

• Not just switching on: you must test the system before you leave it.
• Before switch-on: check that all terminals are tight and no bare wire shows.

What is on the commissioning checklist?

1. The “sniff” test: turn the system on. Smell for burning and listen for “popping” sounds. If you notice either, switch off immediately.
2. Voltage verification: use a multimeter on the battery. For a 24V bank, the reading should be about 24V to 28V, depending on the sun.
3. Polarity check: confirm that plus (+) went to plus and minus (-) went to minus. Wrong polarity is a common cause of blown fuses.

What faults can commissioning reveal?

How do you hand over the system and keep records?

Handover is the stage where you teach the customer to use the system and record the final state of the installation.

In the mock project, the “customer” is your teacher.

What goes into the handover talk?

• Explain the lights: “When this light is green, you are fine. When it turns red, stop using the freezer.”
• Maintenance tips: show how to wipe dust off the panels with a soft cloth.
• The logbook: write down the final battery voltage and the time the system was finished. This is the “birth certificate” of the installation.

What is the group reflection?

After the mock installation, discuss these questions with your team to improve for the real SSCE practical.

• What was the hardest part?
• Did the project manager lead well?
• What would you do differently next time?

Evaluation

1. Why should the charge controller be installed at eye level?
2. List the four steps of the golden wiring sequence in order.
3. Why is the inverter connected to the battery and not to the charge controller?
4. Name the three checks in the commissioning checklist.
5. What should you write in the logbook at handover?

Assignment

Write a short handover talk for a customer using your mock system. Include what the green and red lights mean, how to clean the panels, and what you recorded in the logbook.