SSCE Past Questions – Practical SS3 Solar Photovoltaic Installation & Maintenance Lesson Note

Class: SS3

Subject: Solar Photovoltaic Installation and Maintenance

Topic: Real-Life Case Studies and Practical Problem Solving

Case Study 1 – The “Dim Light” Mystery

The Scenario: A health center in a rural village has 4 solar panels and 2 large batteries. The nurses complain that the vaccine fridge stays on all day, but by 2:00 AM, the “Low Battery” alarm starts beeping, and the lights go dim.

The Practical Task: As a technician, how do you investigate this using your tools?

The Step-by-Step Solution:

1. Check the Load: First, list everything plugged in. If the nurses added a television or an electric kettle without telling the installer, the battery will drain too fast.
2. Test the Battery Voltage: Use a Multimeter. If the battery reads 12.6V during the day but drops to 10.5V immediately after the sun goes down, one of the batteries is likely “dead” or has a “dead cell.”
3. Check for Shading: Look at the panels at 4:00 PM. Is a nearby tree branch casting a shadow? Even a small shadow can cut the power production of a panel by half.

Case Study 2 – The “No Charging” Fault

The Scenario: The sun is shining brightly in Kano, but the charge controller screen shows 0.0 Amps flowing into the battery.

The Practical Task: Find the break in the “energy chain.”

The Step-by-Step Solution:

1. The Fuse/Breaker: Check the fuse box between the panels and the controller. A power surge might have blown the fuse to protect the system.
2. Cable Continuity: Use your multimeter’s “continuity” setting (the one that beeps). Test the cables to see if a wire has snapped or been chewed by a rodent.
3. Panel Voltage (Voc): Disconnect the panels and measure the voltage directly from the wires. if you get 0V, the problem is on the roof (likely a loose mc4 connector).

Case Study 3 – Installing in a “Tight Space“

The Scenario: A customer wants solar for a small shop in a crowded market. The roof is very small and partially blocked by a taller building next door.

The Practical Task: Select the best equipment for this specific environment.

The Step-by-Step Solution:

1. Panel Choice: Since space is small, recommend Monocrystalline panels. They have higher efficiency, meaning they produce more “Watts per square meter” than blue Polycrystalline panels.
2. Controller Choice: Use an MPPT Controller. Because there might be some partial shading from the tall building, an MPPT is smarter at finding whatever little energy is available compared to a PWM controller.
3. Positioning: Use a compass to ensure the panels face South (for Nigeria) to get the longest amount of sun during the day.

Case Study 4 – The “Inverter Beeping” Alarm

The Scenario: You are called to a house where the inverter is making a continuous “Beep” sound and the red “Fault” light is on. The owner says it happened while they were ironing clothes.

The Practical Task: Identify the error and explain it to the customer.

The Step-by-Step Solution:

1. Identify “Overload”: Explain that an iron uses a lot of heat, which requires a massive amount of “Current.” The inverter beeped because the demand was higher than its capacity (e.g., trying to draw 2000W from a 1500W inverter).
2. The Reset Procedure: Switch off the iron. Turn off the inverter, wait 30 seconds, and turn it back on.
3. Customer Education: Advise the customer to check the “Wattage” label on their appliances. High-heat items (heaters, irons, kettles) should only be used one at a time, or when the sun is at its peak.

Practical Skills – The Tool Box

In the SSCE Practical exam, you may be asked to identify tools or explain their use.

The “Must-Know” Tools List:

• MC4 Crimping Tool: For making secure, waterproof connections between panel wires.
• Hydrometer: (For Lead-Acid batteries) To check the “strength” of the battery acid.
• Angle Finder / Inclinometer: To make sure the panels are tilted at the correct angle (usually 15° to 20° in Nigeria).
• Wire Strippers: To remove insulation without cutting the copper strands inside.

Final Tip for the Practical Exam: Always talk about Tight Connections. In solar, a “loose wire” is a “fire.” Most practical problems in Nigeria are caused by heat melting loose wires!