PV System Installation Steps I – SS1 Solar Photovoltaic Installation & Maintenance Lesson Note (Third Term)

PV system installation is the process of fixing solar panels and their supporting equipment safely on a building.

• Order of work: safety preparation, panel mounting, Balance of System (BOS) installation, then cable management.
• Aim: the system stays firmly in place and is safe to repair later.

Behavioural objectives

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

1. List the personal protective equipment (PPE) needed for roof work and state why each item is used.
2. Describe how rails and clamps are used to mount solar panels.
3. State what the “Balance of System” (BOS) means and where the inverter, controller and distribution board should be placed.
4. Explain how conduits, a drip loop and trunking are used to manage cables.
5. State the installer’s three golden rules.

What safety preparation is needed before installing a PV system?

Safety preparation means wearing protective equipment and organising the work area before anyone climbs to the roof.

• Wind danger: a solar panel acts like a giant sail, so wind can pull a person off the roof.
• Heat danger: panels and roofing sheets become very hot in the Nigerian sun.
• Electrical danger: a panel produces electricity whenever light falls on it, even before it is connected.

What is personal protective equipment (PPE)?

PPE is the clothing and gear a worker wears to prevent injury on the job.

How is the work zone organised?

• Tools: keep them in one place and do not scatter them on the ground or roof.
• Batteries: store them in a cool, dry place.
• Panels: keep them in their boxes until the moment they are ready to go up.

Step 1: How are the solar panels mounted?

Panel mounting is the fixing of panels on aluminium rails so they stay in place for the whole life of the system, about 25 years.

• Goal: the panels must not move, even in the heaviest rainstorm or strong wind.
• Rule: panels are never screwed straight into the roof.

How are the rails fixed?

Aluminium rails are metal bars bolted to the roof structure, and the panels sit on them.

1. Find the wooden or metal beams (purlins) under the roofing sheets.
2. Bolt the aluminium rails firmly into the purlins.
3. Check each rail with a spirit level to make sure it is straight.

How are the panels laid and clamped?

Clamps are metal pieces that pinch the panel frame tightly onto the rail.

1. Lift each panel carefully and place it on the rails.
2. Fix the clamps to hold the panel tightly.
3. Use a compass one last time to check that the panels face south.

What is the difference between an end clamp and a mid clamp?

• End clamp: holds the outer edge of the first or last panel in a row.
• Mid clamp: sits between two neighbouring panels and holds both at once.

Step 2: How is the Balance of System (BOS) installed?

The Balance of System (BOS) is everything in a PV system except the solar panels.

• Inverter: changes direct current (DC) into alternating current (AC) for household use.
• Charge controller: controls the charging of the batteries.
• Protection boxes: hold the devices that guard the system.

Where are the inverter and controller placed?

What is the distribution board (DB box)?

A distribution board is a small plastic or metal box that holds the system’s safety devices.

• Position: fixed near the inverter.
• Circuit breakers: switch off the circuit when the current is too high.
• Surge protectors: guard equipment against sudden voltage rises.
• Benefit: all the “safety guards” are kept in one place.

Step 3: How are cables managed?

Cable management is the neat and safe routing of wires so they are protected and easy to trace.

• Problem: wires that look like a “plate of noodles” are hard to fix and can be dangerous.

1. Using conduits: on the roof, wires go inside flexible pipes. This protects them from the sun and from sharp roof edges.
2. Making a drip loop: where wires enter the house, the wire is given a small downward curve. Rainwater drips off the lowest point instead of following the wire inside to the inverter.
3. Using trunking: inside the house, white plastic covers hide the wires along the wall. This also gives a neat, professional finish.

What are the cable management terms?

• Conduit: a flexible pipe that protects wires on the roof.
• Drip loop: a small curve in a wire that makes water drip off before it enters the building.
• Trunking: a plastic cover that holds and hides wires on a wall.

What are the installer’s three golden rules?

The three golden rules are short safety and quality habits every installer must follow.

1. Never walk on the panels: you may not see a crack, but you can break the tiny cells inside.
2. Tighten every screw: a loose screw creates heat, and heat can cause fire.
3. Stay clean: wipe fingerprints off the panels with a soft cloth when the job is done.

What class practical activities can students do?

1. The spirit level challenge: practise using a spirit level on a desk or window frame. If the bubble is in the middle, the surface is level.
2. Tool identification: lay out a spanner, a screwdriver, a clamp and a rail. Students name each one and say what it does on the roof.
3. The drip loop drawing: students draw a house with a solar panel and show how the wire enters the wall so rain stays out.

Evaluation

1. Name the three items of PPE for roof work and state what each one is for.
2. Why are aluminium rails fixed to the purlins before the panels are laid?
3. What is meant by “Balance of System”? Name three parts of it.
4. Why must the inverter and controller be in a well-ventilated place?
5. What is a drip loop and why is it used?

Assignment

In your notebook, write one short paragraph on each of the three installation steps (mounting the panels, installing the Balance of System, and managing cables). In each paragraph, state one rule an installer must follow and give the reason for it.