Practical (Small Solar Set-Up) – SS1 Solar Photovoltaic Installation & Maintenance Lesson Note (Second Term)

The Goal and the “Shopping List”

Today, we are building a 12V DC Lighting System. This is a “DC-only” setup, which means we are not using an inverter. We are running lights directly from the battery.

What we need:

1. Solar Panel: A small 10W or 20W panel.
2. Charge Controller: A small 10A PWM controller.
3. Battery: A 12V 7Ah or 12Ah battery (like the ones in UPS systems).
4. Bulbs: 12V DC LED bulbs (Careful! Don’t use normal “house” bulbs).
5. Wires: Red and Black flexible wires.
6. Tools: A small screwdriver and a wire stripper.

Safety Warning: Even though 12V won’t give you a painful shock, if you touch the Positive and Negative wires together, they will spark and could burn your fingers or ruin the battery. Always be careful!

The Most Important Rule (The Sequence)

Before we touch any wires, you must learn the Golden Rule of Solar Assembly:

Connect the Battery FIRST.

If you connect the solar panel to the controller before the battery, the controller will get “confused.” It needs the battery to “wake up” and know if it is working with a 12V or 24V system.

The Order:

1. Battery to Controller.
2. Solar Panel to Controller.
3. Load (Bulbs) to Controller.

Step-by-Step Assembly

Step 1: The Battery Connection

• Strip the ends of your red and black wires.
• Put the Red wire into the battery (+) port on the controller and the Black wire into the battery (-) port.
• Connect the other ends to the battery terminals.
• Result: The screen on your charge controller should light up!

Step 2: The Solar Panel Connection

• Take your solar panel outside (or near a sunny window).
• Connect the Red wire from the panel to the Solar (+) port on the controller.
• Connect the Black wire to the Solar (-) port.
• Result: You should see a “Sun” or “Arrow” icon on the screen showing that the battery is now charging.

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Step 3: Connecting the Lights (The Load)

• Most controllers have a port with a “Lightbulb” icon.
• Connect your 12V LED bulb wires here. (Red to +, Black to -).
• Result: Your bulb should light up!

Why connect to the Controller instead of the Battery? You could connect the bulb directly to the battery, but if you do that, the battery might drain until it “dies.” By connecting to the controller, the controller will automatically turn the light off if the battery gets too low, protecting your battery.

Testing and Troubleshooting

Now that it’s working, let’s learn how to check if everything is okay.

What if the light doesn’t turn on?

• Check the Polarity: Did you mix up Red and Black? LED bulbs only work if the wires are the right way round.
• Check the Battery: Is the battery dead? If the controller screen is blank, the battery might be too low to start the system.
• Check the Controller Settings: Some controllers have a “Timer” or a “Manual” button to turn the light on and off. Make sure the “Load” is switched ON.

Class Practical Exercise

1. The Shadow Test: While the system is charging, have one student cover the solar panel with a cloth. Watch the controller screen. What happens to the “charging” icon?

The Measurement: Use a Multimeter to check the voltage of the battery while it is charging and again after you turn on the light.