PIKSOL: A SOLAR PIXEL
Piksol is a novel way of decorating sun-facing facades of buildings, which combines the freedom in the visual design of facades with capabilities of collecting solar energy on the facade. A piksol is an object representing a single pixel of an image to be visible on a facade. When attached to a sun-facing facade of a building, it plays a double role (see Fig. 1 below)
the form of the piksol casts a shadow on the facade, representing a (black) pixel of the image/pattern to be visible on the facade
the solar cells on the top of the piksol collect the sun energy and transform it to electricity
Figure 1. A single piksol.
An observer standing in the front of a facade decorated by piksols does not see the solar cells at all, but only the pattern or an image conceived by a designer, visible as a light/shadow variation on the facade. On a cloudy day, when there is no direct sun illumination of the facade, the partern is hardly visible.
Figure 2. A facade covered with piksols on a sunny day.
Piksols in a shadow casting panel
While the basic usage of piksols as described above already has several advantages over just covering a facade with solar cells, we think that the concept of piksol becomes particularly interesting in combination with so-called shadow casting panels: piksols used in a shadow casting panel can be used for creation of dynamic facades, which not only collect solar energy, but also change their appearance during the day, as the direction of sun illumination changes:
in the morning image_A would decorate the facade, and in the afternoon image_B would become visible.
Figure 3. Piksols as building blocks of a shadow casting panel.
Piksols can also be used to create colorful images on facades, by using solar cells with frames made of transparent plastics, similarly as in the case of colorful shadow casting panels.
We have built a small prototype of a shadow casting panel contaning several piksols made of paper and small solar cells, as presented on the images below. In a full-size realization on a facade all the plates of a panel should be replaced by piksols, to maximize the collection potential of solar energy.
Simple piksols made of paper and small solar cells
An overview of a shadow casting panel containing several piksols
Two views of the panel under different directions of light
Two views of the panel under different directions of sunlight.