Nowadays, Tesla Motors is on everyone’s lips. They are not manufacturing cars, they are trying to revolutionize the mobility and use of energy on a global scale, as described in their master plan written by co-founder Elon Musk. [1], [2]

Regardless of what you think about fossil fuels, climate change, etc., I think that the “Tesla experiment” is fascinating under many perspectives, far beyond the industrial/manufacturing/business issues.

Recently, I found out that my dentist purchased a 90 kWh Tesla Model S a weeks ago. As soon as I had the chance, I asked him about it. He talked to me about the car enthusiastically. Besides listing all its amazing technical features, he confirmed that this car truly represents a complete new concept of mobility.

I have no doubt that these vehicles represent a quantum leap in the car industry and I firmly believe that their cost will decrease over the years. However, I think that the key challenge to make these cars available for the masses is partially out of the control of Tesla. In my opinion, the crucial issue that needs to be solved is in fact related to the electric energy production and distribution, even if my dentist tried to convince me otherwise.

According to Tesla’s master plan, the underlying assumption is that sooner or later, almost everybody will own a solar plant equipped with an accumulator, which will be able to recharge the batteries overnight. Therefore, Tesla car owners will be able to provide sufficient energy to power their own cars.

In order to verify if this is reasonable with the technology we have available today, I’m going to do some simple math. I’m going to use real numbers that are relative to my house, where a 2.25 kWp photovoltaic plant is installed, and realistic mileage based upon my car usage. I think my case is a good example of the average potential user of full electric vehicles.

For the sake of simplicity, let’s assume:

  • That I am able to store all the energy produced by my plant
  • That the energy production is equally distributed throughout the year  [3]

My plant was put into service in the summer of 2012. In the period 2013–2016, it produced this amount of energy:

  • 2013: 2606 kWh
  • 2014: 2297 kWh
  • 2015: 2384 kWh
  • 2016: 2312 kWh

On average, it produced about 6.6 kWh per day.

During the same period, my home used this amount energy:

  • 2013: 3112 kWh
  • 2014: 3044 kWh
  • 2015: 3340 kWh
  • 2016: 3513 kWh

Therefore, the average consumption has been 8.9 kWh/day.

My mileage is about 20000 km/year, meaning that I drive on average 55 km each day.

As an example, let’s consider the Tesla Model 3, the car for the masses. Its battery capacity is 60 kWh, and its electric range is about 350 km. Therefore, it can travel for  about 5.8 km per each stored kWh.

To achieve my daily mileage, I would need 9.5 kWh of energy. If we sum this consumption to the home’s need, we have a total of 18.4 kWh/day.

To get a sufficient amount of energy to fuel my car and to power my domestic loads, I would need to increase the surface of the my solar system by a factor of almost three. Alternatively, I would need photovoltaic panels with triple efficiency. The first option is unfeasible, because I don’t have that physical space on the south side of my roof. In regards to the panels, I don’t think that any of the foreseeable improvements of the common photovoltaic technology would be able to triple the current efficiency. So, how could I overcome these hurdles?

If I think about my country (Italy), I can picture one solution that, in theory, can work. However, I think it is hard to implement it in the near future. Since the majority of car owners would not be energetically self-sufficient, they would need a widespread network of chargers. Tesla claims that they guarantee the presence of one supercharger/destination charging site every 200 km or less, but I think this would not be enough for the average user. I believe that way more chargers would be required, even if I don’t think it would be required to achieve the same territorial spread of filling stations. But even so, a huge financial investment to build such a network would be required. Moreover, the existing national electric distribution system would probably not be able to carry the required  amount of energy. Thus, a significant enhancement of the existing infrastructure would be required as well. Another significant question to consider, is who would pay for it? It’s improbable that a country with a debt-to-GDP ratio of about 133% could afford such a huge expense.

Tesla is working hard to solve (or to mitigate, at least) these problems and I really hope that they will succeed.


The development of home batteries and solar roofs is a step in the right direction, but realistically, I still don’t think that Tesla cars will be common within next 10 years.


I really hope I’m wrong, because driving such a car would be amazing indeed!





[3] This may be a strong simplification. In my case, it is indeed, because energy production largely varies throughout the year.