This teaching unit combines the topics of energy, economics, and sustainability in a practical school context. Students learn how ecological investments are evaluated economically and how fact-based decision-making works.

 The aim of the lesson is to teach students from grade 9 upwards the principle of economic efficiency using a practical example: the investment in a photovoltaic system on the school roof.

 The unit was designed to develop fundamental economic concepts such as cost types, amortization, break-even point, and profitability using realistic scenarios. Economic thinking is closely linked to sustainability issues – that is, the understanding that ecologically sound investments can also be economically viable.

 In this lesson, students will explore the fundamentals of economic efficiency using simple examples such as operating a lemonade stand. They will then apply this knowledge to analyzing real-world offers for a school photovoltaic system. The goal is for them to be able to assess the economic viability of the investment and make an informed decision.

 The lesson comprises two teaching blocks of 45 minutes each:

 • Block A: Introduction to basic economic concepts such as absolute profits, fixed costs, unit costs and profitability, illustrated by everyday examples (pizzeria, lemonade stand).

 • Block B: Applying knowledge to a real school photovoltaic system. The students compare three installer offers, calculate amortization periods, total yields and economic efficiency indicators, and make a well-founded investment decision.

 Subject: Economics, Business and Law
 Year group: from year 9 onwards
 Duration: 2 x 45 minutes

 With the support of the sustainability foundation of the Munich municipal savings bank, the teaching unit "Economic efficiency of a school photovoltaic system" was developed and published, and is available for free download here.

 We sincerely thank the Munich Savings Bank's Sustainability Foundation for its generous support. This funding has enabled the development of a high-quality, practice-oriented learning program that empowers young people to consider economic and ecological perspectives together – an important step towards shaping a sustainable future.