Lesson 7 – T: Transform Your Learning: How Do We Match Solar Supply to Energy Demand in a Mini-Grid?

T: Transform Your Learning

Make a Recommendation When Supply and Demand Do Not Match

In real engineering, systems are often limited by money, space, weather, or available equipment. That means the first design does not always work perfectly. Engineers then decide what to change.

Look at the clinic example again with additional loads.

Mini-Grid Data Demand Table (Load Profile)

Load Name/Device	Quantity (Number of Devices)	Power Per device (W)	Hours Per Day	Daily Energy
LED exam room lights	4	10	6	4 x 10 x 6 = 240
Ceiling fans	2	60	8	2 x 60 x 8 = 960
Vaccine refrigerator	1	120	10	1 x 120 x 10 = 1200
Phone charging station	1	100	3	1 x 100 x 3 = 300
Water pump	1	400	2	1 x 400 x 2 = 800
Laptop charging area	3	65	4	3 x 65 x 4 = 780
Night security light	2	20	10	2 x 20 x 10 = 400
Additional fans	2	60	8	2 x 60 x 8 = 960
			Total daily demand	5,640 Wh

Mini-Grid Daily Supply Table (Solar Production)

Panel Power (W)	Number of Panels	Sun-hours Per Day	Daily Solar Energy (Wh)
250	4	5	250 x 4 x 5 = 5000 Wh

Explain with Evidence:

Illustration of a solar-powered healthcare clinic showing how available electricity is prioritized during normal operation and power outages. Rooftop solar panels capture sunlight and generate electricity, labeled "Solar Supply." Inside the clinic, electrical demand is divided into two categories. Priority loads, highlighted in yellow, include a vaccine refrigerator and emergency lighting that remain powered because they are essential for health and safety. Non-critical loads, highlighted in blue, include extra ceiling fans and a laptop charging area that operate only when sufficient power is available. A callout labeled "Energy Demand" explains that electricity powers essential devices and systems inside the building. A flow diagram at the bottom summarizes the process: Sunlight → Electricity Generated → Power to the Clinic → Priority Loads Keep Running → Non-Critical Loads Use Available Power, concluding with the message: "Better Health. Stronger Futures. Sustainable Energy."

The system no longer makes enough daily energy, engineers could choose one or more of these changes:

Add panels
Reduce run-time
Remove a noncritical load
Protect priority loads first
Move some device use to daytime only

Engineering Notebook

How did you decide whether the system could meet the need? If it could not, what change did you recommend and why?

Check Your Understanding

What is the difference between power and energy?
How do you calculate daily energy demand?
How do you estimate daily solar supply?
What does it mean when demand is greater than supply?
What trade-off did you recommend to fix the supply/demand issue.

Closure: Connecting Lesson 7 to Lesson 8

In this lesson, you compared daily solar supply with daily energy demand and used trade-offs to improve a mini-grid design. In the next lesson, you will explore what happens when sunlight is not available and how batteries help solar systems stay useful and reliable over time.

Final Takeaway

Engineers use load profiles and daily supply tables to compare how much energy people need with how much solar power a system can produce in a day. If demand is greater than supply, they must revise the design by adding capacity or reducing less important loads so the system can meet real-world needs.