Module 4 · Evaluate, operate, and explain a system · lesson 12 of 12 · 20 min lab

Lab: explain a complete residential solar system

By the end: Produce a plain-language system brief that distinguishes functions, assumptions, and unresolved questions.

The final exercise combines the parts into a coherent explanation. Imagine handing your brief to a homeowner who wants to understand what they are buying. The goal is not to sell the system. It is to make the energy path, limits, and questions visible.

Use precise verbs: modules generate, inverters convert, batteries store, meters measure, and tariffs value exchanges. Avoid “solar eliminates the bill” and “battery means whole-home backup.” Both claims skip information that must be checked. A clear unknown is more useful than a confident guess.

Your turn

Case: a proposal lists fifteen 400 W modules, microinverters, roof racking, monitoring, and an optional 10 kWh usable battery. It estimates 9,000 kWh/year. The home uses 10,000 kWh/year. The export tariff, backed-up circuits, and battery power rating have not been supplied.

Produce

Draw and label the path from sunlight to loads and grid.
Calculate array nameplate kW DC and annual generation/use ratio.
Explain why that ratio is not the same as bill savings or self-sufficiency.
List six questions covering roof, tariff, backup, approvals, service, and modeling.

Judge your own work against this

Names the separate functions correctly.
Computes 6 kW DC and 90% annual energy ratio.
Does not invent battery runtime or guarantee savings.

Stuck? One hint

Separate what the evidence shows from what still needs verification. Use the worked examples in this module.

Show one good answer — after you have written yours

One defensible response

15 × 400 W = 6,000 W = 6 kW DC. 9,000 ÷ 10,000 = 90%.
The 90% compares annual quantities; timing, imports, exports, and prices remain unknown.
Request roof/attachment assessment, tariff details, backed-up circuits and kW limits, utility/permit responsibilities, service terms, and production-model inputs.
A 10 kWh capacity alone cannot establish backup runtime or which appliances can start.

Quick check

Which sentence accurately describes a utility meter?

End of module 4

Evaluate, operate, and explain a system

That was the last module. The final exam and practice quizzes are on the course page. Go to the course page →

Lab: explain a complete residential solar system

By the end: Produce a plain-language system brief that distinguishes functions, assumptions, and unresolved questions.

Your turn

Produce

Draw and label the path from sunlight to loads and grid.
Calculate array nameplate kW DC and annual generation/use ratio.
Explain why that ratio is not the same as bill savings or self-sufficiency.
List six questions covering roof, tariff, backup, approvals, service, and modeling.

Judge your own work against this

Names the separate functions correctly.
Computes 6 kW DC and 90% annual energy ratio.
Does not invent battery runtime or guarantee savings.

Stuck? One hint

Separate what the evidence shows from what still needs verification. Use the worked examples in this module.

Show one good answer — after you have written yours

One defensible response

15 × 400 W = 6,000 W = 6 kW DC. 9,000 ÷ 10,000 = 90%.
The 90% compares annual quantities; timing, imports, exports, and prices remain unknown.
Request roof/attachment assessment, tariff details, backed-up circuits and kW limits, utility/permit responsibilities, service terms, and production-model inputs.
A 10 kWh capacity alone cannot establish backup runtime or which appliances can start.

Quick check

Which sentence accurately describes a utility meter?

End of module 4

Evaluate, operate, and explain a system

That was the last module. The final exam and practice quizzes are on the course page. Go to the course page →