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Solen, the lighting experts, at Vivatech with ENGIE

Smart buildings
04/07/2017

Solen was created a year and a half ago by three engineers. The startup describes itself as the “luminosity experts” and provides an app for real estate professionals to easily assess brightness and sunlight levels within a home. Solen has been invited to ENGIE's Energy Lab at Viva Technology, and Clément Henry, co-founder and CEO of Solen, answered our questions.

Hello Clement. Can you give us a short introduction to Solen?

Solen has developed a technology that allows a user to simulate the brightness potential and sunlight levels of a specific location for every day of the year, just based on pictures taken on a mobile phone. It can assess one room or several rooms within an apartment, an outside patio, a garden, a playing field etc.

Our current targets includes real estate professionals, agencies, and promoters. This is a strategic choice, since 80% of real estate transactions are carried out by professionals. In the long term, we fully plan to offer it to individual users as well.
One of the other uses we are considering is for assessing photovoltaic and energy saving potential. There are many potential uses for our technology.

What is innovative about your project?

It is innovative primarily in that it combines several different technologies.

  • First, the phone is situated in space with its GPS position, its orientation and its inclination. We then retrace the trajectory of the sun around the phone using astrophysics models.
  • We then use optics to adapt to accommodate the focal distance of the phone.
  • Finally, we incorporate image processing, since for each photos we determine the areas of open sky and which nearby buildings could potentially obstruct brightness and the sunshine.

We are not the only company that calculates luminosity levels – this is already being done by traditional architecture and design offices. But they need very powerful 3D software and a lot of computing power to do this. Such studies take several days and multiple staff members to complete. Our solution uses mobile phone sensors, which are becoming more and more precise. We are currently able to calculate luminosity levels to within 5% of the levels assessed by a conventional design office.

And our turnaround is only 24 hours, although eventually the process will be fully automated. We currently have check all the information manually before sending it.
So we issue luminosity level assessments that provide room-by-room information about direct sunlight and natural brightness for every hour of every day of the year.

Do you need to have a wide range of expertise to combine all these technologies?

Yes, the founders are all engineers with very different specialties.
Thomas is had the idea of the application. He is a climate engineer and handles the algorithmic and product part.
Enzo is our computer engineer. He is responsible for developing the technical solution and implementing it for our customers.
I’m an industrial engineer with a background in supply chain issues, and I handle project management, sales, financing, and communications.

Will you be showing your app at VivaTech?

Yes, definitely. The app (which is free) includes an augmented reality module that we call Solen Live. People particularly like to use it during apartment visits, since it uses augmented reality picture to show how luminosity levels will vary. This is what we want to show first and foremost during VivaTech, especially for the general public.
We will also present a product that we’ve developed for real estate developers who sell as-yet unbuilt apartments. For this we conduct the luminosity assessment using 3D modeling of the future building. We offer salespeople an interface that lets them simulate the future development with a playful aspect wherein they can vary brightness room by room.

What do you expect to get from being at Vivatech?

First of all, we are very happy to be located at the ENGIE Lab, where we hope to meet people and find new synergies.

We have just completed a Proof of Concept with the help of two partners, Foncia for the existing real estate and Bouygues for new developments. We spent 6 months testing the app on both markets. We are now at the critical point where we want to find agencies to work and grow with. We are also raising seed funding. We hope to meet investors who are interested in our product, our team and our vision. Even though we’ve chosen to address the real estate market, we know that our project can be used in many other areas, In particular that of energy, in particular photovoltaics.

To finish this interview, you will have to ask yourself a question ... and answer it!

I'm sure you're dying to know how we got the idea of this app...

Definitely! Tell us about it!


At first, 18 months ago, we imagined an app that would geo-reference restaurant and café street terraces in Paris based on their sunshine levels. The idea was to be able locate and promote the sunniest ones to the users of our app. So we referenced more than 300 bars in Paris, developed a true community of sun spotters and sun lovers, but failed to find profitable business model. And that's how we switched to real estate. Our longer-term vision is that Solen becomes a multi-channel brand that the general public can use at any stages of their lives for brightness and sunshine issues: buying or renting a home, holiday rentals, choice of a bar in the sun, sports, installing photovoltaic panels, doing home renovation, gardening, etc.