Comprehensive Revision I SS3 Solar Photovoltaic Installation & Maintenance Lesson Note

Class: SS3

Subject: Solar Photovoltaic Installation and Maintenance 

Topic: Major Theory Concepts for SSCE Preparation

The Foundation – Solar Cells and Panels

To pass your theory exam, you must be able to explain how we get electricity from the sky. It isn’t magic; it’s physics.

Key Concepts to Remember:

• The Silicon Cell: Almost all solar panels are made of Silicon (from sand). When sunlight hits this silicon, it excites “electrons” and makes them move. This movement of electrons is what we call Electricity.
• Monocrystalline: Think of this as “Premium.” It is made from a single, pure crystal. It is dark black and works very efficiently even if the roof is small.
• Polycrystalline: These are made from many crystals melted together. They look blue and “marbled.” They are cheaper but you need more of them to get the same power as Mono panels.

Exam Tip: If a question asks why we use glass on top of the cells, the answer is “Protection.” It protects the cells from rain, wind, and bird droppings while letting 95% of sunlight pass through.

The Energy Managers (Controllers & Inverters)

A solar panel produces “wild” electricity. If you connect it directly to a battery, it might overcharge it. If you connect it to a TV, it won’t work. We need managers.

1. The Charge Controller:

• PWM (Pulse Width Modulation): It’s like a simple light switch. When the battery is full, it turns the power off. It’s cheap but loses some energy as heat.
• MPPT (Maximum Power Point Tracking): It’s like a smart computer. It “tracks” the sun and converts extra voltage into extra current. It is much more efficient.

2. The Inverter: Your panels give DC (Direct Current), but your fan needs AC (Alternating Current).

• Pure Sine Wave: This is the “Clean” power. It is exactly like the power from the national grid. Use this for fridges, fans, and computers.
• Modified Sine Wave: This is “Rough” power. It’s okay for simple things like bulbs, but it can make your fans hum loudly or damage sensitive electronics.

Battery Wisdom and Storage

In the theory exam, you will definitely be asked about how we store power for the night.

Important Definitions:

• Deep Cycle: Unlike a car battery that gives a quick “start,” a solar battery is built for a long, slow “jog.” It can be drained and recharged every day for years.
• State of Charge (SoC): Think of this as your phone’s battery percentage. 100% means full.
• Depth of Discharge (DoD): This is how much you have used.
  1. Warning: If you have a Lead-Acid battery, never go past 50% DoD. If you do, you are “killing” the battery’s lifespan.

Series vs. Parallel:

• Series: Connect (+) of one battery to (-) of the other. This increases Voltage (e.g., two 12V batteries become 24V).
• Parallel: Connect (+) to (+) and (-) to (-). This increases Capacity/Amps (the voltage stays at 12V, but you can use it for longer).

System Protection and Safety

A good technician is a living technician. The exam always tests your knowledge of how to prevent fires and shocks.

The “Safety Triangle”:

1. Fuses and Breakers: These are the “Weakest Link” on purpose. If there is a power surge, the fuse “dies” so that your expensive Inverter doesn’t have to.

1. Earthing (Grounding): We bury a copper rod in the ground and connect the metal frames of the panels to it. If lightning strikes or a wire touches the frame, the “killer” electricity goes safely into the earth.
2. Isolation: Always install a “Disconnect Switch” between the panels and the controller. This allows you to turn off the power completely before you start repairs.

Practical Tip for Theory: If asked how to put out a solar fire, never use water. Use a CO2 or Dry Powder fire extinguisher because solar systems involve live electricity.

Environmental Impact and Policy

The government and the world care about why we use solar. You might get an essay question on this.

Sustainability Points:

• Zero Emissions: Solar doesn’t breathe out smoke. This helps stop the “Greenhouse Effect” (Climate Change).
• Decentralization: You don’t need big wires from a distant city. Every house can be its own power station. This is the heart of Rural Electrification.
• Economic Growth: Small businesses (Barbing salons, Tailors) can work at night without buying expensive petrol for generators.

The “30:30:30” Policy: Nigeria’s goal is to reach 30,000MW of power by the year 2030, with 30% of that coming from renewable energy. As an SS3 student, you are the generation that will build this!