What this lesson teaches
I can evaluate solar power and hydropower as ways to replace fossil fuels securely and sustainably.
Syllabus 9173, Topic 1.1, 3. Managing Resources. How do we manage the use of renewable energy sources?
Make a guess
A country installs huge solar farms that produce more than enough power at midday. Is its electricity now secure?
- No, not yet. It still needs power after sunset.
- Yes, because sunshine is free.
- Yes, because capacity is bigger than demand.
- No, because solar power works poorly in the tropics.
Show the answer
No, not yet. It still needs power after sunset.
Solar output changes through the day and with clouds. Security needs storage, grids or other sources to meet the evening peak.
Solar power can replace fossil fuels, but reliable electricity needs a system that also works when the sun is weak.
Solar panels turn sunlight into electricity. They can reduce the fuel burned in power stations and protect a country from swings in imported fuel prices. Rooftop panels produce power close to users.
Energy security means reliable energy at a reasonable price. Solar output changes through the day, with clouds and with the seasons. So the capacity installed is not the same as power available when needed. A big midday surplus does not meet an evening peak.
Batteries can store some power for later, but they cost money and lose some energy. Stronger grids, links with neighbours, flexible demand and other power sources also help. A mix of sources is usually more reliable than one.
There are trade-offs. Economically, panels cost money upfront but save fuel later. Environmentally, they cut emissions but need land, mined materials and disposal. Socially, homeowners with good roofs and money gain more easily than tenants or poorer households.
- Energy security
- Reliable energy at a reasonable price.
- Intermittency
- Solar output varies by hour, weather and season.
- Balancing
- Storage, grids, flexible demand and other sources.
Step by step
Match output to demand
When is sunlight available, and when is power needed?
Find balancing options
Storage, grids or other power sources.
Count full costs
Money, materials, land and who benefits.
Worked example: The evening gap
In a made-up grid, solar produces 80 MW at noon but 0 MW after dark. Evening demand is 70 MW. Batteries may help if large enough, but other supplies are needed too. The noon figure alone does not show security.
Watch out for this
Renewable electricity has no environmental costs.
Solar avoids burning fuel, but panels and land use still have impacts.
Check your understanding
What best tests whether solar improves energy security?
- The highest midday output across the year.
- Comparing demand, solar output and backup over time.
- Counting the panels installed in each district.
Show the answer
Comparing demand, solar output and backup over time.
Yes. Security means power is there when needed.