Comprehensive Revision II – SS3 Solar Photovoltaic Installation & Maintenance Lesson Note (Third Term)

A solar photovoltaic practical exam tests how safely and correctly you use tools, connect components, find faults, service a system and report your work.

Behavioural objectives

1. Name the main tools used in solar installation and state what each is used for.
2. Connect two batteries or two panels in series and in parallel.
3. Find simple faults in an inverter and a charge controller by following the energy path.
4. Carry out a basic service routine safely.
5. List what to write in a final commissioning report.

What safety rules apply before any practical work?

Safety rules are the steps you take to protect yourself, the equipment and other people before you touch a solar system.

• Isolate the system: switch off the breaker and disconnect the load before working on wiring.
• Remember panels stay live: panels produce voltage whenever light falls on them.
• Use insulated tools: a bare metal tool can short a battery and cause a spark.
• Wear protective gear: use gloves, safety goggles and safety shoes.
• Remove metal jewellery: rings and chains can touch live terminals.
• Take care on roofs: never work alone and keep your footing secure.

Which tools should a technician know for the practical exam?

The main tools are the digital multimeter, crimping tool, wire strippers, inclinometer and insulated spanners, and the examiner watches how you handle each one.

• Digital multimeter: measures voltage and shows whether a battery is charged or a panel is producing power.
• Crimping tool: fixes MC4 connectors to the ends of solar cables. A good crimp cannot be pulled off by hand.
• Wire strippers: remove the plastic insulation without cutting the copper strands inside.
• Inclinometer (angle finder): checks that panels are tilted at the correct angle, usually about 15 degrees in most parts of Nigeria.
• Insulated spanner set: tightens battery and terminal bolts safely.
• Screwdrivers: tighten terminals on the controller, inverter and breakers.

Using the wrong tool, such as a kitchen knife to strip a wire, loses marks.

How do you prepare a multimeter before testing?

1. Set the dial to DC voltage for panels and batteries, or AC voltage for the inverter output.
2. Choose a range higher than the voltage you expect, if the meter is not auto-ranging.
3. Check the leads for breaks: touch the probes together on the continuity setting and listen for the beep.
4. Place the red probe on positive and the black probe on negative.

How do you connect components in series and in parallel?

Series and parallel are the two ways of joining batteries or panels, and each one changes the voltage or the current and capacity.

What is a series connection?

A series connection joins the positive (+) of one component to the negative (-) of the next to add their voltages.

1. Join the positive (+) of component A to the negative (-) of component B.
2. Take the free negative (-) of A and the free positive (+) of B to the controller.
3. Check the total voltage with the multimeter.

This is how two 12V batteries make a 24V bank.

What is a parallel connection?

A parallel connection joins positive to positive and negative to negative to keep the voltage the same and add current or capacity.

1. Join the positive (+) of A to the positive (+) of B.
2. Join the negative (-) of A to the negative (-) of B.
3. Take one positive and one negative lead from the joined points to the controller.

For batteries, the bank has more capacity (Ah) and runs the load for longer. For panels, the current adds up.

What is the difference between series and parallel?

What is the common exam trap?

• Wrong controller setting: if you join batteries in series and the controller is set to 12V, it may show an “Overvoltage” error.
• Fix: set the controller to match the battery bank voltage, then check the display.
• Mixed components: join only batteries or panels of the same voltage and rating.

How do you troubleshoot a faulty system?

Troubleshooting is finding a fault by checking each part along the energy path from the panels to the load.

1. Solar panels collect the energy.
2. The charge controller regulates the charging.
3. The battery stores the energy.
4. The inverter changes DC to AC.
5. The load (bulb, fan, TV) uses the energy.

Start at the load or at the part that is not working, then check one part at a time. Do not panic.

Scenario 1: The inverter is on, but the bulb is not lighting

• Check 1: is the AC breaker or switch turned on?
• Check 2: measure the AC output of the inverter with the multimeter.
• Result: if the inverter gives about 220V but the bulb is dark, the bulb is dead or the wire is broken.

Scenario 2: The charge controller screen is blank

• Check 1: is the battery connected? Most controllers will not switch on without battery power.
• Check 2: check the fuse between the battery and the controller.
• Result: if the fuse is blown, the controller has no power to start.

Scenario 3: The inverter will not switch on

• Check 1: measure the battery voltage. A very low battery stops the inverter.
• Check 2: check the DC fuse or breaker and the battery cable connections.
• Check 3: confirm the polarity is correct, positive to positive and negative to negative.

Scenario 4: The battery is not charging

• Check 1: measure the panel voltage (Voc) to see whether the panels are producing power.
• Check 2: look for shade, dirt or loose MC4 connectors.
• Check 3: check the controller display and settings.

How do you service a solar installation?

A service routine is a set of regular checks and cleaning steps that keep the system working safely.

1. Isolate the system: switch off the breakers before you handle any wiring or terminal.
2. Panel cleaning: use a soft sponge and water. Check for hotspots (dark burnt spots on the cells) while you clean.
3. Terminal cleaning: white “beards” on battery terminals are corrosion. Clean them with warm water and a wire brush, then apply petroleum jelly.
4. Tightness test: use an insulated spanner to check every bolt gently.
5. Final test: switch the system on and read the voltages with the multimeter.

Warning: never tighten a live terminal with a metal spanner that is not insulated. It can cause a large spark.

What goes into the final commissioning report?

A commissioning report is the written record of your tests and findings, made before you hand the project over.

• Site details: the client, the location and the date of the work.
• Voc (open-circuit voltage): the voltage of the panels when they are not connected to anything.
• Vbat (battery voltage): the voltage of the batteries before and after charging.
• System polarity: write “Polarity was verified to ensure positive to positive and negative to negative.”
• Controller settings: the battery voltage setting used.
• Faults and action taken: any problem found and how you fixed it.
• Observations: shading problems or structural concerns with the roof.

How should you leave the work site?

• Tools: put them back in the bag.
• Waste: clear away wire off-cuts.
• Result: a clean site is a safe site, and examiners reward it.

Evaluation

1. State the use of a crimping tool and a wire stripper.
2. How would you connect two 12V batteries to make a 24V bank?
3. The charge controller screen is blank. Give two checks you would make.
4. Why should you never tighten a live terminal with a metal spanner that is not insulated?
5. List four things to write in a practical report.

Assignment

Write out the step-by-step service routine for a solar installation. For each step, state what you would do and one safety point to remember.