Solar Panel Mounting Structures – SS1 Solar Photovoltaic Installation & Maintenance Lesson Note (Second Term)

A solar panel mounting structure is the frame that holds solar panels in place on a roof, on the ground, on a pole or over a car park.

Behavioural objectives

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

1. Name and describe the four types of mounting structure.
2. State the direction solar panels should face in Nigeria and give a reason.
3. Explain what the tilt angle is and why panels are tilted at about 15° to 20°.
4. List three things to check during a site assessment.
5. Name materials suitable for mounting structures and say why they are used.

What are the types of mounting structures?

There are four types of mounting structure: roof mounts, ground mounts, pole mounts and carport mounts.

• Roof mounts: the most common in Nigeria, with aluminium rails bolted to the roof to hold the panels.
• Ground mounts: a metal stand built on the ground, used when the roof is too small or faces the wrong way.
• Pole mounts: one panel sits on top of a single pole, as on solar streetlights.
• Carport mounts: panels form the roof of a car park, giving shade for cars while making electricity.

Roof mounts

• Fixing: aluminium rails are bolted onto the roof, and the panels are clamped to the rails.
• Check first: the roof must be strong enough to carry the weight of the panels.

Ground mounts

• Frame: usually made of galvanised steel or aluminium.
• Advantage: the installer can choose the best direction and tilt.

Pole mounts

• Use: solar streetlights and other small, stand-alone loads.

Carport mounts

• Use: a “two-in-one” structure that shades cars and produces power.

Which way should solar panels face in Nigeria?

Solar panels in Nigeria should face true south.

• Reason: Nigeria is in the Northern Hemisphere (north of the equator), so the sun is to our south for most of the year.
• Facing north: the panel loses a lot of power because the sun is behind it for most of the day.
• If south is not possible: use the shape of the roof to choose east or west.

What is the tilt angle?

The tilt angle is the angle at which a solar panel leans up from the flat ground.

• Recommended angle: panels in Nigeria are usually tilted between 15° and 20°.
• Flat panel (0°): dust and bird droppings gather and block the sun.
• Too steep: the panel catches less sunlight over the year.
• Self-cleaning: 15° to 20° is steep enough for rain to wash dust away.
• Location: places further north, such as Maiduguri, may use a slightly steeper tilt than places further south, such as Lagos.

What is a site assessment?

A site assessment is the inspection an installer does before any work starts, like a doctor examining a patient before giving medicine.

• Shadow test: look for trees, tall buildings or poles that cast shadows, because a small shadow can cut the output of a whole panel.
• Roof health: check that the purlins (the wooden or metal bars under the roof sheets) are not rotten, or the panels may fall through.
• Roof repairs: repair the roof before fixing the panels if it needs it.
• Distance to the battery room: keep it short, because long wires cause voltage drop.

What is voltage drop?

• Voltage drop: the loss of electrical power along a long wire.
• Remedy: place panels, batteries and inverter as close together as is safe.

What materials are used for mounting structures?

Mounting structures are made from materials that do not rust, such as aluminium and galvanised steel.

• Why rust matters: a rusted frame weakens and the panels can fall.
• Coastal areas: salty air in Lagos and Port Harcourt makes rust-resistant materials even more important.

Class activity: the “Sun-Hunter”

1. Go outside to the school compound.
2. Use a compass, or note where the sun rises and sets, to find south.
3. Choose a building on the compound.
4. Decide which side of its roof is best for solar panels.
5. Check whether a tree or another building casts a shadow on that side.

Discussion

• Question: why is ordinary (black) iron a bad choice for a solar stand in Lagos or Port Harcourt?
• Hint: think about salty air and rain.

Evaluation

1. Name the four types of mounting structure.
2. Why do we face solar panels toward true south in Nigeria?
3. What is the tilt angle, and why is a flat panel (0°) a problem?
4. State three things an installer checks during a site assessment.
5. Name two materials suitable for a mounting structure.

Assignment

In your exercise book, write a short note on how you would choose the direction and tilt angle for solar panels on a house roof in your area. Mention one thing you would check on the site before installing.