The new 3D solar panel developed by Fraunhofer IZM is almost invisible when mounted on a ski helmet. Using brand new techniques, the high-performance solar cells can be fit to the curve of a helmet without forfeiting durability and performance.

Together with the TU Berlin and the company TEXSYS, Fraunhofer IZM has developed a new communication module that can be integrated directly into a helmet. It lays the foundation for covering all the power requirements the keen skier may have, including stereo headphones and headsets that will soon be powered solely by energy gained from the solar panels attached to the surface of the ski helmet. Mobile devices like smart phones and MP3 players can then be connected wirelessly via Bluetooth. Incoming calls can be received without breaking glide using the accompanying Bluetooth-enabled glove. The user can even operate an MP3 player remotely from the glove, ensuring that cumbersome removal of gloves in sub-zero temperatures is finally a thing of the past. The result is a complete communication system integrated directly into the ski equipment, does without annoying cables and weighs almost nothing.

How does it work?
Thanks to Fraunhofer IZM’s new solar module, a headset can now be powered directly. It ensures all power requirements are met in any kind of weather. However, this is only possible if large, extremely efficient (> 20 percent) solar cells are used.

Consequently, adapting the solar panel to the curved shape of the ski helmet was the biggest challenge. Until now, only relatively small solar modules could be mounted on uneven surfaces. Mechanically flexible, foil-based solar cells are also unsuited to such applications, as they only bend in one direction (cylindrical) and are usually far less efficient than rigid solar cells.

The problem has been solved by Fraunhofer IZM’s new packaging technology, with which extremely high quality, monocrystalline silicon solar cellars can be divided into tiny individual chips and adapted to a three-dimensional, curved shape. This also strongly reduces the risk of individual cells fracturing when discrete points are subjected to mechanical stress. Moreover, the redundant layout of the solar cells ensures the module keeps operating smoothly even if an individual cell fails.

Possible Applications
This extremely robust technology can be used in many applications that are exposed to outdoor conditions. The power supply is a compact unit comprising the solar module, electronics and battery, ensuring that it can be easily adapted for other applications with curved surfaces, like bicycle and riding helmets, backpacks, clothing and car body parts. Retrofitting conventional helmets with the solar module is also possible. Its use is possible wherever helmet headsets are already standard, such as motorcycle helmets and helmets for rescue teams. Powering a fan with the solar module is also imaginable. The module with a rated output of 2 W, which is the power input required by a smart phone, can easily be integrated into a typical helmet.

Challenges
Development of the battery required special attention to the application area’s low and strongly fluctuating temperatures. Although the solar cells actually perform better at low temperatures, the battery performance declines significantly. Additionally, at sub-zero temperatures recharging is almost impossible. This is where Fraunhofer IZM’s microcontroller comes into play. It makes recharging at temperatures between -30°C and +60°C possible and prevents recharging outside of this range. However, the integrated communication module can still be used during these times providing sufficient light is available, because the power is directly supplied via the solar panel.  Using maximum power point tracking, the microcontroller ensures that the solar cell operates at its maximum under all conditions (temperature, irradiation).

Recharging from the power grid is almost superfluous, due to the efficiency of the 3D solar module on the ski helmet’s surface. Moreover, even when the helmet is not being used, the battery can charge a smart phone or MP3 player. Finding a power point is therefore a thing of the past and, moreover, harnessing the sun’s energy is good for the environment.

Price
A prototype of the solar helmet is already available and the next step involves field tests and a redesign. The solar ski helmet will then be released commercially at the end of the year as a small-series production in cooperation with a major helmet manufacturer at a retail price of around 300 euros. (The modules themselves, which can also be purchased separately, will cost less than 100 euros, depending on the individual specifications.)

The solar helmet is on display at from January 29th to February 1st 2012 at the ISPO Munich trade show. Visit the Fraunhofer booth at the WT show in Hall B6.

The solar helmet will also be exhibited at the Fraunhofer IZM booth during “IDTechEx Energy Harvesting & Storage Europe 2012” in Berlin on May 15th and 16th.