PV System Maintenance II SS2 Solar Photovoltaic Installation & Maintenance Lesson Note

The Mindset of a Troubleshooter

Troubleshooting is like being a detective. You don’t just start pulling wires; you follow the “Path of Power.” Power flows from the Sun → Panels → Controller/Inverter → Batteries → Appliances.

The First Question: Always ask the owner, “What exactly happened?”

• Did it stop working suddenly during a rainstorm? (Could be lightning or a leak).
• Did it slowly get weaker over weeks? (Could be dust or a dying battery).
• Did it stop right after someone plugged in a big freezer? (Overload).

Common Faults – The “Dead” System

If the house has no power at all, we start at the “Brain” (The Inverter).

1. Check the Screen: Most modern inverters will show an Error Code (like E01, F05). Look up this code in the manual.
2. The Tripped Breaker: Check the distribution box. Often, a “fault” is just a circuit breaker that flipped “OFF” because of a power surge. Simply flipping it back might solve it.
3. Blown Fuses: If a fuse has melted, the “bridge” for electricity is broken. You must find out why it blew (usually an overload) before replacing it.

Safety Rule: Never replace a fuse with a piece of copper wire. This is a fire hazard! Always use a fuse with the same Amp rating.

Troubleshooting the Solar Array (DC Side)

If the batteries aren’t charging but the sun is bright, the problem is on the roof.

How to test:

• Visual Inspection: Look for “Hot Spots” (brown burn marks) on the panels. This happens if a cell is cracked.
• Using the Multimeter: Disconnect the string of panels and measure the voltage.
  1. If you expect 100V but see 0V, there is a broken wire or a loose connection in a junction box.
  2. If you see 40V, one of the panels in the string might be faulty or shaded.

Battery Health and Faults

Batteries are usually the first thing to fail in a solar system.

Signs of a Bad Battery:

1. Fast Charge/Fast Discharge: If the battery voltage jumps to “Full” after only 10 minutes of sun, but dies 5 minutes after the lights come on at night, the battery is “sulfated” or dead.
2. Swelling: If the sides of the battery look like they are bulging or “pregnant,” it has been overcharged or exposed to too much heat. Warning: Swollen batteries can be dangerous; disconnect them immediately.
3. Low Voltage: Use your multimeter. A “12V” battery that reads 10V even after a day of sun is likely damaged beyond repair.

Replacing Components Safely

When you find a part that is truly broken, follow these steps to replace it:

The “Power Down” Sequence:

1. Turn off the AC Output (Load).
2. Turn off the PV Input (Panels).
3. Turn off the Battery Switch. Basically: Work from the house back to the batteries.

Replacing a Battery:

• Always disconnect the Negative (-) cable first.
• When installing the new one, connect the Positive (+) cable first. (Think: “Positive is the First to arrive, Last to leave”).

Final Check: After replacing a part, don’t just walk away. Stay for 15 minutes. Check if the connections are getting hot and make sure the inverter screen shows that power is flowing again.

Summary: * Most “broken” systems are just loose wires or tripped breakers.

• Use your Multimeter to “see” where the electricity stops.
• Always turn off the power before touching any terminals.