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

Preventive maintenance is the regular checking, cleaning and tightening of a solar system to stop faults before they cause a breakdown.

Behavioural objectives

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

1. State the common causes of solar system faults in Nigeria.
2. Use sight, hearing and smell to spot signs of a fault.
3. Use a multimeter to test for no power from the panels and for a weak battery.
4. Draw up a preventive maintenance schedule for a customer.
5. Check simple causes when a monitoring app shows the system as “Offline”.

Why do solar systems fail?

Solar systems fail mainly because of heat, dust, loose connections and poor battery care.

• Heat: components get too hot because of poor ventilation.
• Dust: Harmattan dust covers the panels and blocks the sun.
• Loose wires: vibration and heat loosen screws over time.
• Corrosion: white or crusty powder on battery terminals weakens the connection.
• Overloading: connecting more load than the inverter or battery can supply.
• Poor battery care: overcharging or letting the battery run flat shortens its life.

What is the golden rule of maintenance?

• It is much cheaper to maintain a battery than to replace it.
• Good maintenance helps a system last much longer.
• A working mock system needs regular check-ups, like a car.

How do technicians use their senses to find faults?

Technicians find many faults by looking, listening and smelling before they use any test instrument.

1. Look: check for crusty or white battery terminals (corrosion) and for an error code flashing on the inverter screen.
2. Listen: a loud, grinding inverter fan means the fan is failing and the system will soon overheat.
3. Smell, rotten eggs: a lead-acid battery is overcharging and releasing dangerous gas. Switch off and ventilate the room.
4. Smell, burning plastic: check the wire connections immediately for overheating.

What safety rules apply before testing?

Always make the system safe before you touch any wire, terminal or component.

• Switch off: turn off the inverter and open the breakers before cleaning or tightening.
• Remember the panels: panels produce voltage whenever there is light, even if the system is switched off.
• Use insulated tools: a spanner touching both battery terminals causes a short circuit.
• Remove metal jewellery: rings and chains can short a battery.
• Protect yourself: wear gloves and eye protection when working near batteries.

How do you troubleshoot with a multimeter?

A multimeter is an instrument that measures voltage, current and resistance, and it is the main tool for confirming a fault.

Scenario A: no power from the panels

1. Set the meter to DC voltage.
2. Measure at the ends of the wires coming from the roof, in bright sun.
3. Read the result. A reading of 0 V in bright sun means the circuit is broken.
4. Look for the cause: a broken wire, a blown fuse, a tripped breaker or a loose connector.

Scenario B: the inverter keeps shutting down

1. Set the meter to DC voltage and connect it across the battery terminals.
2. Measure the battery voltage while the inverter is running a load, such as a fan.
3. Watch the reading. A sudden drop (for example, from 12.6 V to 10.2 V) means the battery is weak.
4. Conclude that the battery cannot hold a load any more and needs testing or replacement.

What are the common faults and their likely causes?

What is the preventive maintenance (PM) schedule?

A preventive maintenance schedule is a service calendar that tells the customer which task to do and how often.

What tips make the schedule work?

• Clean cool panels: clean early in the morning or late in the day, not when the glass is hot.
• Switch off first: turn the system off before cleaning terminals, tightening screws or blowing dust.
• Keep a record: write the date and task done each time.

How do you solve IoT connection issues?

An IoT connection issue is a digital fault where the monitoring app cannot reach the inverter, even though the power may still be working.

• Smart monitoring sends system data to the app through the internet.
• An “Offline” message does not mean the power is out.

Check these things in order:

1. Check the Wi-Fi: has the router run out of data? Has a new wall or metal door blocked the signal?
2. Restart the dongle: unplug the small Wi-Fi stick on the inverter and plug it back in.
3. Update the software: the app or the inverter firmware may need an update to talk to the hardware correctly.

Evaluation

1. List three common causes of solar system faults in Nigeria.
2. What does a “rotten eggs” smell from a lead-acid battery tell you?
3. You measure 0 V at the ends of the wires from the roof in bright sun. What are the likely causes?
4. State two tasks on the preventive maintenance schedule and how often each is done.
5. Your monitoring app says “Offline”. Name two things you should check.

Assignment

Final project task: In your groups, one student should “create” a small fault (like disconnecting a fuse or shading a panel). The other students must use their tools to find the fault and explain how to fix it. This is how you prove you are ready for the SSCE Practical.