What is the best way to store energy?

04 December 2017 by Kristian Holm
Soon, many of us will have solar panels or a windmill in our back yard. What will be the best way to store surplus energy from these? Could my dream be the solution everyone will be looking for in a few years?

I am, admittedly, a bit of a day dreamer. I am also a bit of a techno-nerd. Consequently, I frequently daydream about our technological future.


One of my recurring daydreams involves a Tesla. Since my wife would never approve of such an investment the subject itself is a big, fat hint that I am daydreaming. That doesn't stop my dreaming though.


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I want a blue Tesla X …

As a fairly big guy I need a big car. In other words, my Tesla would be a Model X. It would be blue with full autopilot features. And it would have that big sound system of 


theirs, because I love to listen to music while driving.


Now, as I mentioned in my previous blog post, energy storage is getting cheaper by the minute and constraints on raw material is not a concern. Since electric cars are also cheaper in use than gasoline-fueled cars and have an added environmental benefit, you might understand why I am convinced that my wife and I will eventuelly own a fully electric car. It might not be a Tesla, but it will be electric.

… and solar panels

Another thing I always come back to in my thoughts – or daydreams – is solar panels. I believe that within the next 5–7 years, my wife and I will have solar panels installed on the roof of our house. As you can see in the picture, the south side of our house is perfectly aligned with the sun, and the roof will fit between 20 and 25 square meters of solar panels.

According to the Norwegian supplier Otovo, installing solar panels on our roof, we could produce 2,900 kWh each year, or about 16 % of our total energy need. And that is in Trondheim, in the middle of Norway and only 570 km south of the polar circle. In the course of its lifetime, such an installation would also improve my otherwise terrible CO2 footprint by 42 metric tons.

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Now this sounds great. A blue Tesla Model X that can be partly charged from my own solar panels. Fantastic!

But how do we store the energy?

There is one small issue I need to resolve before everything is in place: During the daytime, my household uses very little electricity, and my Tesla will generally be at work with me. This means we won’t be able to benefit from the clean solar energy from our roof as a fuel for our electric car.

Our local grid company could buy and utilize the surplus power

They could, but there is a catch: Solar agreements with grid companies usually state that the price for surplus power follows the current market price for electricity. I assume the price of electricity varies with demand – which is low during off-peak periods such as the daytime when the our surplus power would be produced. On top of that, we would have to pay for using the electrical grid. All in all, this seems to be a bad idea.

I need to be smarter.

We could use a local storage system

There is no doubt that we would need every bit of energy our solar panels produced. To be able to utilize it, we would need some type of storage system. Tesla, as well as other suppliers, offers energy storage solutions. They are, however, expensive, and although the price will eventually go down, such systems have limitations. There must be an even smarter solution.

Could we use the electrical grid for energy storage?

Now, this is a solution I find really interesting. If my local grid company offered a flexible cloud storage solution for electrical energy it would solve my problems.

The grid that delivers electric power to the outlets in our house is connected to a multitude of systems that require energy, for instance for heating and cooling the house, heating water, and running motors and pumps. Stored energy would be useful for all of these.

Since the grid is constantly fed with energy, we could use it as a huge battery if we could understand and controll the processes that happen simultaneously inside the electrical power system. It would be a large viral system that continously recalculated its needed behaviour based on usage statistics, energy storage capabilities and energy production estimates. Truly a big data system consisting of the latest components of digital computing.

Put a bit of lithium on top of that mix, and you have an energy-storage system in the cloud. With that I could use energy I create in my home to charge my Tesla when I am on a roadtrip in France. All I'd need would be an application and an agreement with my local grid company

Saving energy to the cloud is about to become reality

It might seem like sci-fi, but I think the only sci-fi part of my daydream is the part about owning a Tesla. The technology pieces needed for creating a cloud-based energy storage system is being developed even as you read this. We need to overcome both commercial and regulatory obstacles before it'll become reality, but I am convinced that it will be part of our future – and likely sooner than we expect.

Do you think using the electrical grid for energy storage is a viable solution? Let me know in the comments below.


About the writer
Kristian Holm
Kristian Holm has been heading the renewables business at KONGSBERG since 2012. He holds a bachelor’s degree in naval design and is currently completing a master in economics. Kristian has been working in the renewables business since 2004 with all aspects of the wind energy business including design, production, and operations of large wind turbines. Between 2009 and 2012 he was heading the production and operations of GE offshore wind.