Exclusive For Kickstarter Backers: Behind The Scenes

Hi Backer! Thanks for supporting us!! Here you can read about how PhotonGrill started as a student’s project and how it became a meticulously designed high quality product. How it all began:

We are living in a big city where space is expensive and most people (including us) do not have a balcony or a garden so we are unable to have a BBQ – BUT we really love to BBQ. For many people like us the only option is to go to a public park and BBQ. One summer’s day we were grilling like normal until the police showed up and told us that there was a fire ban in place…

We didn’t want to accept this ban because summer is not summer without grilling. We then had an idea: We believed in freedom and we wanted the freedom to grill!

So we went on a journey to find a portable grill without an open fire. We discovered sun powered heating technology and its game-changing advantages.
(learn more about the technology of photongrills)

Devices for concentrating sunlight are quite common. However, they are designed for stationary operation only, or they are too weak and do not produce temperatures high enough for *real*grilling. We wanted a grill that would be a consummate grilling companion, that fits into every backpack, that could be taken wherever we wanted. A state of the art tool for city dwellers and outdoor enthousiasts as well. We realized we had to invent something totally new!

2012 – First Prototype: “tub”

The tub was our first model which we built during our summer holiday in 2009. We constructed it based upon the principle of a parabolic tub, because a tub-like mirror made from solid materials is much easier to build than a parabolic dish. The sunbeams are concentrated onto a focal line, exactly where a long frying pan is located which can be sealed with a lid.


Grilling in front of our collage building.

The rack was made from wood. To reach a certain degree of mobility we integrated a basic folding mechanism that allows the transportation with a bigger car.
The mirror surface was made of self-adhesive foil. We learned that having a highly reflective foil makes a huge impact as far as efficiency is concerned. With a highly reflective foil, the grill was able to heat up the pan to 250°C/482°F.


The tub folded up


The tub in action


Concentrated sunlight at the backside of the frying pan


Crispy grilled sausages


Grilling at the ‘Seestadt Aspern’ (city development area in Vienna)



June 2013: SolarFlair

The SolarFlair was the first Photongrill with an inflatable parabolic mirror. We built the first working prototype in summer 2010. Since then we have been developing and improving the mirror . Developments we have made include the welding together of a transparent foil and a reflective foil . The welded foils form an air chamber which is inflated by the use of an air pump. We use the pump as the pressure forces the mirror to form into a parabolic shape.


side view of the inflatable parabolic dish

The inflatable parabolic mirror can be folded up to fit in a backpack and is very lightweight. The rack is segmented like tent poles, so that the whole grill fits into a bag with a length of about a meter, with a total weight of under 5 kg.


Solarflair prototype


Design study for the frame


The SolarFlair in southern french countryside


measuring the termperature (170°C)


parabolic mirror and frying pan


February 2014: SunEye

We started to work on the SunEye in Winter 2011. The SunEye-concept was built upon the idea of inflatables and went even further. We did not just make an inflatable mirror, we also made an inflatable rack. Our prototype will have a mirror diameter of 1.4 m.


The challenge was to ensure that the mirror is movable.This is achieved by use of a ball joint. The mirror is nested into a halved sphere which rests in an inflatable tyre lying on the ground, this makes rotations in all directions possible.


The only thing missing is a simple bracket for attaching the Grill Pan in the focal point. Our prototype will have a mirror diameter of 1.4 m.


For this design we avoided almost all fixed parts, which significantly reduced weight and bulk. Setting up the construction is also much simpler as it is reduced to inflation.

So far, it has remained in experimental status – we believed that the concept of SolarFlair is more promising as far as production is concerned. However, we do not rule out, that we will pick up the SunEye concept in the future.


August 2014: Sunsausage Deluxe (PhotonGrill 1.0)

Regarding the business side we had some very important breakthroughs. We have won a business idea challenge at university, we were then nominated for the INITS start up incabator, and then we also recieved some funding from AWS. This gave us the possibility to focus on refining the SolarFlair concept and it paid off: Our next prototype was the sunsausage deluxe Photongrill, which is already pretty close to what we had in mind:
The grill is lightweight (under 5kg), fits in a backpack, is set up within 5 minutes and – most importantly – it is really powerful. We managed to heat up a pan up to 260 degrees C within 5 minutes…

The technology is based on experiments that NASA carried out in the 90s, when the agency had worked on inflatable space antennas. We went one step further and managed to integrate today’s high-tech materials. Using heat to thermally deform the plastic’s polymers’ structure, the plastic is able to “remember” and transform into the desired parabolic shape when inflated. However, there were problems with durability: after folding the mirror for several times, crease started to occur on the reflective surface. The mirror’s areas where crease was present, were not able to precisely concentrate the light as required which meant that the mirror’s power rapidly diminished after each use. The solution was to attach stiff, crease-resistant mirror platings onto the transparent foil instead of having a flexible reflective foil. To make sure that folding the mirror was still possible, gaps were left between to mirror platings where the foil could be folded. The layout of the mirror plating and gaps leave just one way how the mirror can be folded up, making the folding process simple and self explainatory.


Great user experience: The setup is really simple and the grill is easy to adjust when aligning it towards the sun. And we have already begun working on some cool visual design concepts…


May 2015: PHOTONGRILL2.0!

Finally! Just one step short of making the ultimate portable sun-powered fireless grill come true. We had a breakthrough on the technological side and we had to wait to show the world what we are up to. We just had to wait for our patent application to be finished.

August 2015!
Yes, patent pending aaaaaaand TA-DAH!
PHOTONGRILL 2.0 is here:

A problem was to find a transparent foil that would withstand hot liquids and grease that could drop onto the foil while cooking. Working with a specialized institute and conducting several real-life tests was a costly and time consuming process but it helped to find the ideal foil that is highly robust while also having high transparency. About 10% of power is lost when the light has to pass the transparent foil two times, that’s why a diameter of 1.3m is needed to achieve 1000 watts of power.
The next step was to make the mirror fit into a frame that likewise could be folded and put in a backpack, but also be stable enough to bear the weight of a pot filled with water or food. The frame also had to allow the mirror to be tilted and aligned to the sun. After several attempts of building the frame around the mirror this construction had to be discarded because the mechanical parts would have been prone to defects, been much too expensive and not stable enough.
Calculating and adjusting the foil’s deformation of having a hole inside the mirror made it possible to have a piece of frame through the mirror and have a straight structure as introduced by Müller and Takizawa 14 years ago.
That was the final solution to have a high power parabolic cooker that is lightweight, can be set up quickly and fits in a backpack.




The final outcome:





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