Expert with best answer


100% Recommendation Rate

295 Meetings

1,750 Q&A Upvotes

USD 319 / Coaching

Brain Teaser: Solar panels

Anonymous A asked on May 14, 2018

Greetings everyone! A short time ago I have been asked a question to evaluate the number of solar energy panels (1 sq. meter each) can be placed in France? (explain assumptions.)
And how many of them are needed to cover all demand for energy in France.
How would you answer these questions?


1 answer

  • Upvotes
  • Date ascending
  • Date descending
Best Answer
replied on May 14, 2018
McKinsey Engagement Manager & BCG Consultant | Interviewer at McK & BCG for 7 years | Coached 90+ candidates secure MBB offers
Book a coaching with Sidi

100% Recommendation Rate

295 Meetings

1,750 Q&A Upvotes

USD 319 / Coaching

Hi Anonymous,

first of all - this is not a brain teaaser, but an ordinary estimation question! Here is a high-level approach:

I would start with the second question, because it is most straight forward:

1. Clarify the required generation capacity in France (a Gigawatt figure)

2. Clarify the generation capacity per square meter of solar panel

3. Divide 1 by 2

Regarding the first question:

1. Brainstorm a list of facilities where solar panels can be installed (of course roofs, but there might be additional areas)

2. Estimate a maximum percentage for each kind of installation facility that can be used for solar panel installations

3. Estimate the average installation area (in sqm) available for each facility type

4. Estimate the number for each facility type (e.g. number of roofs in France)

5. Multiply 4 with 3 and with 2 for each facility type and add up the results. This is the overall (potential) installation area of solar panels in France (in sqm). Since a panel has 1 sqm size, this is also the number of panels.

Cheers, Sidi

Related BootCamp article(s)

Important Facts

It's essential to know some key figures regarding geographies, population, economies for your case interviews. We summarized them for you here.

Brain Teasers

Learn how to tackle brain teasers and what purpose they serve in consulting case interviews

Market Sizing

Market Sizing Cases are used to test your quantitative and reasoning skills. The interviewer evaluates your structure, numbers-handling and business sense.

1 Q&A

Typical Question Types in Written Tests

Questions among all tests can be categorized in math, GMAT-style, chart reading and brain teaser questions. Each type needs to be approached differently.

Related case(s)

Your client, large automotive OEM WyCar, has developed its first fully electric vehicle (EV) and introduced it as a pilot on the Austrian market last year. However, sales have been far below the expected numbers. The management has engaged you to support them in understanding the reasons and advise ... Open whole case

Bain Case: Old Winery

Solved 30.8k times
4.4 5 842
| Rating: (4.4 / 5.0)

You have inherited the “Old Winery” from your grandfather, a winery which has been family owned for five generations and can be dated back to the 16th century. Half of the eleven hectares are used to grow white grapes, the other half to grow red grapes. They are grown in the conventional way, i.e. ... Open whole case

Roland Berger Case: Onlinestar

Solved 18.6k times
4.3 5 407
| Rating: (4.3 / 5.0)

Onlinestar, an online retailer of furniture and garden products (core business), has grown significantly in recent years as a result of an expansion of its product portfolio. The company mainly imports goods from Chinese manufacturers but also operates its own production of cat lavatories (special b ... Open whole case


Solved 49.2k times
4.5 5 1525
| Rating: (4.5 / 5.0) |

Nutripremium is a very well-known premium nutrition food company in Europe (€1 billion revenue last year). It is based in Spain and has an excellent market share not only in its home country but also in Portugal, France, Italy and Germany. Nutripremium has two main lines of products: Vitamin-supp ... Open whole case

Children vaccine

Solved 44.5k times
4.4 5 1487
| Rating: (4.4 / 5.0) |

Beyer, one of the biggest pharmaceutical companies in the world, just invented a very reliable vaccine against Chickenpox, a disease that affects children in the age from 2 to 16 years. Beyer came to you wondering what their potential sales in Europe in the first year would be if they launched this ... Open whole case