“Invisible” Solar Roof from SolarCity

October 30, 2016 by Jeff Shepard

SolarCity in conjunction with Tesla and 3M has developed a family of "invisible" solar roof tiles. The secret to the tiles' appearance is a special coating that becomes more or less see-through depending on the viewing angle. The company is working with 3M specifically on the coating technology for the tiles which were described it as a series of micro louvers that work like a privacy screen on a laptop computer. From shallow angles, the tiles appear nontransparent. But as the viewing angle approaches 90 degrees, the underlying solar cell becomes more and more visible.

SolarCity had announced last August that it was planning to add solar roofs to its offering. During an earnings conference call, the company called solar roofs, "a fundamental part of achieving a differentiated product strategy." At the same time, SolarCity and Tesla are working together to introduce the second-generation of Tesla’s Powerwall energy storage system.

The new roofing tiles are actually a laminated three-layer structure. The bottom layer is a high-efficiency solar cell capable of operating efficiently at higher temperatures. The solar cell is covered by the 3M coating that allows the cells to blend in with the roof while minimizing solar efficiency loss (the layer is 98% transmissive when viewed directly from the vertical. The top layer is tempered glass which makes the entire assembly very rugged, and able to withstand nearly three times the force of standard roofing tiles. The tiles will initially be offered in four styles, Tuscan, Smooth, Textured and Slate.

The solar roofs are designed to be used with the new Tesla Powerwall Version 2.0. The new Powerwall is flatter than the first version, which Tesla released in April 2015. It will cost $5,500 for 14kWh of storage and 7kWh peak power draw. According to Tesla, that is enough to power a four bedroom house for a day.