Energy-use survey of the school
Count the bulbs, fans and hours used, then work out how much solar the school would need.
The big idea
A school is a small town of its own. Counting how much it uses lets students plan, save and imagine a school that runs on the Sun.
You will need
Tick things off as you gather them.
Step by step
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Step 1: Split into teams
Divide the school into zones: classrooms, labs, offices, halls and outdoors. Give each team one zone.
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Step 2: Count what you see
In your zone, count every bulb and tube, every fan, every computer and other electric device. Note the wattage on each, or use a typical value.
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Step 3: Find the hours
Ask staff how many hours a day each item is switched on. Include weekends, if used.
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Step 4: Work out the units
For each item: number × watts × hours ÷ 1000 = units per day. Add up the units for your zone.
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Step 5: Combine the teams
Add the zone totals to get the school's daily units. Multiply by the school days in a month for a monthly total.
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Step 6: Compare with the bill
Check your total against the bill from the office. How close is it? What have you missed?
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Step 7: Size a solar system
In most of India, one kilowatt of solar panels makes roughly 4 to 5 units on a sunny day. Divide the daily units by 4 to get the kilowatts needed. Roof space is roughly 7 to 10 square metres for each kilowatt.
What to look for
- Lights and fans are usually the biggest users in a classroom.
- A small number of rooms often account for much of the total.
- Switching off when rooms are empty could save a lot of energy.
Why it works
Energy use is power times time. A school has hundreds of small loads, and they add up. Once you know the total, you can ask two questions: how can we use less, and how much solar would cover the rest? Saving units first is always cheaper than making more. These are the same questions engineers ask before they design a solar system.
Try this next
- Pick three ways to save and test them for a month.
- Use your shadow map to choose where the panels would go.
- Present the plan to the school principal.
Link to the grid
A school with solar panels can feed spare power back into the grid. Surveys like this one are the first step in every real solar plan.
Learn how the grid works