Learner Lesson 7: How Do We Match Solar Supply to Energy Demand in a Mini-Grid?
Lesson Overview
In the last lesson, you learned how photovoltaic panels are built and how engineers compare panel specifications. In this lesson, you will take the next step and think like a mini-grid designer. A solar panel may produce electricity, but that does not automatically mean a system can meet the needs of a school, clinic, or community. Engineers must compare how much energy people need with how much energy the system can supply over a day.
You will build a simple load profile, estimate daily solar energy production, and decide whether a mini-grid design is likely to work. Then you will make a recommendation about what to change if the system cannot meet the full demand.
Questions You Will Be Able to Answer by the End of This Lesson
- What is the difference between power and energy in a mini-grid?
- How do engineers calculate daily energy demand?
- How do engineers estimate daily solar supply?
- What happens when energy demand is greater than energy supply?
Key Vocabulary and Concepts
|
Term |
Definition |
|---|---|
|
Load |
A device that uses electrical energy, such as a light, fan, motor, or appliance. |
|
Load profile |
An organized record or representation of which electrical loads are used, how much power and energy they require, and when or how long they are expected to operate. A load profile describes electricity demand over time. It may be created as a table of devices and operating times or as a graph showing power demand across a day, week, or year. |
|
Daily energy demand |
The total energy needed by all loads in one day. |
|
Daily energy supply |
The total energy a solar system can produce in one day. |
|
Sun-hours |
The equivalent number of hours per day of strong sunlight used for estimation – also called peak sun-hours. |
|
Reliability |
The extent to which a system can perform its intended function without failure under stated conditions over a specified period of time. |
|
Constraint |
A limit or condition that restricts possible design choices and must be considered when developing a solution. Constraints can include cost, time, available materials or equipment, space, safety requirements, weather, and location. |
|
Priority load |
A load that is more important to keep running than others – also called critical loads. |
|
Resistance (R) |
A measure of how much a material or component opposes the flow of electric current. It is measured in ohms (Ω)(\Omega)(Ω). For a given voltage, higher resistance results in less current flow. |