PV System Installation Steps II SS1 Solar Photovoltaic Installation & Maintenance Lesson Note

The “Battery First” Rule 

Before you touch a single solar panel wire, you must remember the most important rule in solar installation: Always connect the batteries to the inverter and charge controller first.

Why? The Charge Controller is like a computer. It needs to “wake up” and see the battery voltage (12V, 24V, or 48V) before it can start accepting power from the sun. If you connect the panels first, the high voltage from the sun might “confuse” or even fry the controller’s brain because it doesn’t know where to send the energy.

Connecting the Batteries (The Power House)

When we connect batteries to the inverter, we are dealing with very high “current.” This means the wires must be very thick.

1. Clean the Terminals: Make sure there is no dust or “white powder” (corrosion) on the battery heads.
2. Tighten with a Spanner: Do not just twist the wires with your hands. Use a spanner to tighten the bolts. A loose battery connection will cause sparks and can melt the battery terminal.
3. Color Code: * RED goes to Positive (+).
   1. BLACK goes to Negative (-).
   2. Tip: If you mix these up, you will hear a loud “BANG,” and the inverter will likely blow up. Always double-check!

Wiring the Solar Panels to the Controller

Now that the battery has “woken up” the controller, we can bring the power down from the roof.

1. The DC Disconnect: Before the wires enter the controller, we put a Circuit Breaker (switch). We keep this switch OFF while we are joining the wires.
2. MC4 Connectors: On the roof, we use the “click-and-lock” plugs. Ensure they click firmly so that rain doesn’t enter.
3. Polarity Check: Use your Multimeter to check the wires coming from the roof. Ensure the one you think is “Positive” actually shows a (+) sign on your meter.

Connecting the Inverter to the House

This is the “AC” side. This is the power that can actually kill, so we must be extremely careful.

1. The Change-over Switch: You must never allow the Solar Inverter and the “NEPA” (Grid) power to meet. If they meet, the inverter will explode. We use a Change-over Switch so the house can only use one source at a time.
2. The Output Wiring: * Live (Brown/Red)
   1. Neutral (Blue/Black)
   2. Earth (Green/Yellow)
3. No Overloading: We don’t connect the heavy things like Water Heaters or ACs to the inverter unless the system was specifically designed for them.

The “First Start-Up” (Commissioning)

Once everything is wired, we don’t just turn everything on at once. We follow a “Slow and Steady” path:

1. Switch 1: The Battery Breaker. Turn this on. The inverter screen should light up.
2. Switch 2: The Solar Breaker. Turn this on. The controller should show that it is “Charging.”
3. Switch 3: The AC Output. Turn this on to send power to the house.
4. The “Smell & Sound” Test: Stand near the system for 5 minutes. Do you smell anything burning? Do you hear any strange “hissing” sounds? If everything is silent and cool, you have done a great job!

Class Practical Activity

1. The Terminal Check: Give the students a battery and a thick cable. Practice tightening the bolt with a spanner until it doesn’t move.
2. The Multimeter Test: Show the students how to test for “Continuity” (to see if a wire is broken inside).

The Warning Label: Ask students to design a “Danger: High Voltage” sign that they would hang on a real solar installation.