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

The Mock SSCE is an internal practice exam that works as a dress rehearsal for the final SSCE in Solar Photovoltaic Installation and Maintenance.

Behavioural objectives

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

1. State the role of the panel, charge controller, inverter and battery.
2. Describe the path of energy from sunlight to household appliances.
3. Calculate the total daily load using the step-by-step method.
4. Explain the difference between watts and watt-hours.
5. Answer scenario questions on common solar faults.
6. Apply time-management and answer-writing strategies in the exam.

What does the Mock SSCE test?

The Mock SSCE tests recall of definitions and the ability to solve problems like an engineer on the field.

• Component roles: what each part does (panels, controllers, inverters, batteries).
• System connections: how energy flows from the sun to the bulb.
• Safety protocols: how to stay safe when working with electricity.
• Energy conversion: how sunlight becomes usable power.
• Load calculation: how to find the energy used in a day.
• Troubleshooting: how to find the likely cause of a fault.

• Use of the result: it shows where your knowledge is strong and where it is weak.
• Marking: clear, well-organised answers earn more marks.

What does each main component do?

A solar PV system has four main components, and each has one clear job.

How does energy conversion work in a solar system?

Energy in a solar system moves in four stages: light to DC, regulation, storage and transformation to AC.

1. Light to DC: sunlight hits the silicon cells in the PV panel. The photovoltaic effect produces DC electricity.
2. Regulation: the charge controller controls the raw power so the battery does not overcharge and get damaged.
3. Storage: the energy is kept in the battery bank as chemical energy.
4. Transformation: the inverter converts the stored DC (direct current) into AC (alternating current) for household appliances.

• Mock tip: when asked to draw a diagram, label every arrow to show the direction of current flow.

How do you calculate the total daily load?

The total daily load is the sum of the energy, in watt-hours (Wh), that all appliances use in one day.

What are the steps for calculating load?

1. List the power (watts) of each item.
2. List the hours of use for each item per day.
3. Multiply watts × hours to get the energy (Wh) for each item.
4. Add everything together to get the total daily load.

What is a worked example?

Find the total daily load of four 10 W bulbs, one 60 W fan and one 80 W television.

• Tip: write the unit in every line of working, because marks are given for correct units.

What is the difference between watts and watt-hours?

A watt (W) is the unit of power, which is the rate at which an appliance uses energy.

A watt-hour (Wh) is the unit of energy, which is the power used multiplied by the time of use.

• Common mistake: students write watts as the final answer for daily load. The final answer must be in Wh.

How do you answer troubleshooting scenario questions?

A scenario question describes a fault, and you must state the likely cause and the action to take.

Scenario 1: slow, humming fan

“The customer says their inverter is working, but their fan is spinning very slowly and making a humming noise.”

• Likely cause: a modified sine wave inverter is being used instead of a pure sine wave inverter.
• Reason: inductive loads such as fans and fridges need pure sine wave to run smoothly.

Scenario 2: low panel output

“A 200W panel is only producing 20W at midday.”

• Shading: trees or buildings block sunlight from the panel.
• Dirt: heavy dust or dirt on the glass reduces the light reaching the cells.
• Loose connector: a loose MC4 connector causes high resistance.

Scenario 3: inverter beeps and shuts down

“The inverter beeps and switches off when the customer adds a pressing iron.”

• Likely cause: the total load is higher than the inverter rating (overload).
• Action: switch off some appliances, or use an inverter with a higher rating.

How should you structure a scenario answer?

1. State the likely cause in one line.
2. Give the reason in one line.
3. State the action you would take to correct it.

How are batteries connected in series and in parallel?

Batteries are connected in series to increase voltage and in parallel to increase capacity.

What safety rules apply to installation questions?

The “safety first” rule means you state safety precautions before and during any installation or maintenance answer.

• PPE: wear personal protective equipment such as gloves, safety glasses and safety boots.
• Loose connections: check all connections before switching on the system.
• Isolation: switch off and isolate the system before working on it.
• Panels stay live: panels produce voltage whenever light falls on them.
• Roof work: work carefully at height and never work alone.

What is the best exam day strategy?

Good exam strategy means reading instructions, planning your time and presenting answers clearly.

1. Read the instruction: check whether Section B asks for three questions or four. Do not answer more than you are asked to.
2. Plan your time: share the time among the questions and move on if you are stuck.
3. Sketch first: for drawing questions (like wiring a battery bank in series), sketch lightly in pencil before using your pen. This prevents messy cancellations.
4. Use bullet points: for maintenance or safety, bullets make your points easy for the examiner to see and mark.
5. Apply the “safety first” rule: for installation questions, always mention wearing PPE (personal protective equipment) and checking for loose connections.
6. Show working: in calculations, write each step and the unit.

Evaluation

1. Name the four stages of the energy path, from sunlight to household appliances.
2. State the four steps for calculating the total daily load.
3. Explain the difference between watts and watt-hours.
4. A customer’s fan spins slowly and hums when connected to the inverter. Give the likely cause.
5. List three possible reasons why a 200W panel produces only 20W at midday.

Assignment

1. Draw the energy path from the PV panel to a household appliance. Label each component and use arrows to show the direction of current flow.
2. Write short notes on the “safety first” rule for installation questions, using bullet points.