Mock Installation Project I – SS3 Solar Photovoltaic Installation & Maintenance Lesson Note (Second Term)

A mock installation is a classroom practical in which students carry out every step of a real solar installation, from the customer interview to the final wire, in a safe controlled setting.

Behavioural objectives

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

1. describe the five group roles in a mock installation;
2. carry out a site survey and load audit by listing appliances, their wattage and their running hours;
3. state the direction solar panels should face in Nigeria and why;
4. draw a schematic diagram that shows the panel array, protection box and battery bank;
5. follow the three golden rules when wiring the system;
6. test the finished system and present the group’s work.

What is the mock installation project?

The mock installation project is a group task to design and install a solar power system for a small 2-bedroom apartment.

• Group size: each group has five students.
• Task: design the system and “mock-install” it in the workshop.
• Coverage: the group follows every step a professional takes, from talking to the customer to connecting the final wire.
• Setting: the work is done in a controlled classroom environment so that everyone stays safe while learning.

What are the group roles?

There are four role titles in each group of five: Project Manager, Sizing Specialist, Safety Officer and Installer (two students).

1. Project Manager: keeps the team on schedule and handles the “Customer Interview”.
2. Sizing Specialist: does the calculations and chooses the right battery and panel sizes.
3. Safety Officer: ensures everyone wears protective gear and checks for wire “hotspots”.
4. Installer (2 students): mounts the panels and wires the batteries.

What tools and safety gear does the group need?

The group needs measuring tools, hand tools and protective gear before any wiring starts.

• Compass: finds South for the panel direction.
• Multimeter: measures battery voltage during testing.
• Spanners: tighten terminal bolts.
• Cable ties: hold wires neatly in place.
• Protective gear: gloves and safety goggles, checked by the Safety Officer.

How do you carry out the mock installation?

The mock installation has four stages: site survey and load audit, system design, installation, and final testing with presentation.

Step 1: What is a site survey and load audit?

A load audit is a list of every appliance in a building with its power rating and daily running hours.

A doctor does not give medicine without checking the patient. In the same way, a technician does not install panels without a load audit.

Practical task for the group:

1. List every appliance in the “Mock Apartment” (for example, 5 LED bulbs, 2 standing fans, 1 LED TV, 1 laptop).
2. Check the wattage of each appliance.
3. Estimate how many hours each will run in a day.
4. Calculate the energy used: energy (Wh) = power (W) × hours.
5. Add up the total power and total energy.

Sample load audit (the wattages and hours are example values only):

The “real world” check of the roof

• Shade: look at the roof area given to your group. Check for a chimney or water tank casting a shadow on the panels.
• Direction: use your compass to find South.
• Why South: Nigeria lies north of the equator, so the sun stays mostly in the southern part of the sky.
• Result of facing North: the panels receive less sunlight, so the batteries will not charge fully and your project will “fail”.

Step 2: What goes into the system design and wiring plan?

A schematic diagram is a simple drawing that shows every part of the system and how the parts connect.

Your design must include:

• The panel array: decide whether to connect the panels in series or in parallel.
• The protection box: show where the DC breakers and the surge protector will be placed.
• The battery bank: show how two 12V batteries are connected to match a 24V inverter.

What is the difference between series and parallel connection?

In a series connection, the positive terminal of one unit joins the negative terminal of the next.

In a parallel connection, all positive terminals join together and all negative terminals join together.

For this project, connect the two 12V batteries in series to give 24V for the 24V inverter.

Step 3: What are the golden rules of the mock installation?

The golden rules are three wiring habits that protect the equipment and the people in the group.

Even though the work is in a workshop, treat every wire as if it is “live”.

1. Connect the battery first: always connect the battery to the charge controller before you connect the panels. If you do it the other way round, you might damage the controller’s “brain”.
2. Tighten the terminals: a loose bolt creates heat, and heat can cause a fire. Use your spanners to make sure nothing wiggles.
3. Manage the cables: do not let wires hang like “spaghetti”. Use cable ties to keep the installation neat and professional.

Step 4: What is commissioning?

Commissioning is the final testing of a solar system to confirm that it works safely and correctly.

The checklist for success:

• Voltage test: use your multimeter to check the battery voltage.
• Charging test: check that the controller shows an “arrow” pointing from the panel to the battery.
• Load test: switch on the bulbs and check that they do not flicker. The inverter should run with a steady hum and without a warning beep.

How does the group present its work?

Each group stands by its project and answers three questions.

• Battery size: why did you choose this specific battery size?
• Challenge: what was the biggest challenge you faced during wiring?
• Safety: how did the Safety Officer ensure no one got shocked?

Teacher’s note: professionalism counts. A system that works but looks messy will get lower marks than a neat, well-organised system.

Evaluation

1. What is a load audit, and why must it be done before installation?
2. Which direction should solar panels face in Nigeria, and what happens if they face North?
3. Why must you connect the battery to the charge controller before you connect the panels?
4. How do you connect two 12V batteries to match a 24V inverter?
5. Name the three tests in the commissioning checklist.

Assignment

1. In your notebook, write the three golden rules of the mock installation and give one reason for each.
2. Draw a schematic diagram showing two 12V batteries connected in series to a 24V inverter. Show where the DC breakers and surge protector would go in the protection box.