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KYOCERA Explains Innovations Used in Solar Panel for New Toyota Prius

Solar panels for automotive use born from Kyocera’s 30-plus years of experience

September 15, 2009
Photo: Solar modules for automotive use are produced at the Ise Plant (Mie Prefecture, Japan)
Solar modules for automotive use are produced at the Ise Plant (Mie Prefecture, Japan)
Kyocera Corporation (President: Tetsuo Kuba) is currently suppling solar modules for the new Toyota Prius solar ventilation system, an optional feature for the hybrid vehicle introduced by Toyota Motor Corporation. For Kyocera, this marks the first time its solar modules have been used in a mass-produced automotive application. Three years ago, a project group referred to as “T-Pro” was established within the Corporate Solar Energy Group of Kyocera in order to develop high-quality solar modules for automotive use — an application which demands an exceptionally high level of quality — and also to establish a dedicated production line.

1. Ensuring quality that meets the high standards required for onboard components used on the new Prius

Onboard components for automotive applications must pass strict quality control evaluations for severe onboard conditions. Kyocera ensures high-quality modules by applying our expertise which has been cultivated with more than 30 years of experience, and by implementing strict quality control evaluations performed through rigorous testing to confirm heat-, vibration- and shock-resistance as well as many other critical factors. The criteria for quality testing is set beyond the official standards to ensure performance, quality and a long service life.

2. A high level of aesthetic quality with uniform cell coloration

Photo: To mask the electrodes, the glass is pre-painted, requiring a high degree of accuracy. In addition to high functionality and performance as an automotive component, a high level of aesthetic quality was also required of the design of the solar modules to be mounted on the roof of the Prius.

Since 2002, Kyocera has offered high-performance solar cells that utilize a unique Reactive Ion Etching (RIE) technology. RIE is a technology utilized to create microscopic ridges on the surface of the cell using plasma and reactive gases. The subtle ridges allow the solar cells to better absorb the sunlight reflected on the surface, therefore enhancing conversion efficiency and power output.

At the same time, a uniform dark navy blue color has been realized to achieve a sleek and stylish appearance. Normally, the coloration of solar cells within the same module slightly differs based on the thickness of the anti-reflection coating. For the solar modules used on the new Prius, Kyocera achieved strict color uniformity of the cells.

To cover up the silver electrodes on the front surface of the solar cells, the glass encasing was painted with black stripes. To mask the electrodes perfectly without covering the cells requires a high degree of accuracy in the layout of cells and painting in order to achieve a high level of aesthetic quality.

3. Curved shape of the solar module

Normally, solar modules are completely flat, however, the solar modules for the new Prius are curved to conform with the design of vehicle’s roofline. Taking into account the curvature, Kyocera brought in a specialized laminator to the dedicated production line to seal the solar cells, glass and back sheet into the uniquely-shaped solar module. Photo: Curved shape of the solar modules
Curved shape of the solar modules