One of the most fascinating aspects of Tesla’s solar roof, which started reaching homes earlier this year, is that it looks like an ordinary roof. The design hides advanced energy-harvesting cells wired to a home battery, and a new patent application published last week by the United States Patent and Trademark Office sheds light on how the company pulled off the technical feat.

Tesla’s description of the invention, as listed in the patent’s abstract, explains the tile “includes a backsheet layer, a bottom encapsulant layer adjacent the backsheet layer, a plurality of photovoltaic cells adjacent the bottom encapsulant layer, a top encapsulant layer adjacent the plurality of photovoltaic cells having a plurality of louvers constructed therein to block side view of the plurality of photovoltaic cells, and a top layer adjacent the top encapsulant layer.” In other words, the louvers inside the tiles act like blinds in a window. The light hitting the roof from the sky passes through, but from the street level the louvers block the sight of the cells and make the tiles appear smooth.

The Tesla Solar Roof image included with the patent.
The Tesla Solar Roof image included with the patent.

The breakthrough is a key part of Tesla’s strategy to bring about an energy revolution. When CEO Elon Musk unveiled the tiles in October 2016, he said it “needs to be beautiful.” The tile was unveiled as part of a “house of the future” vision, with a Tesla Model 3 electric car in the garage and a Tesla Powerpack battery storing leftover energy.

Tesla touts the tiles as a price-competitive alternative to a standard roof, and it’s here that the invention really shines. The company offers its four styles with a combination of solar and non-solar tiles, with the former costing $42 per square foot and the latter $11 per square foot. Tesla claims an average price of $21.85 per square foot based on a mix of 35 percent solar tiles versus non-solar. To maintain the aesthetics of the roof, the tiles need to look identical from the street level.

The company has already launched two styles of tile. The smooth and textured styles started rolling out from the Buffalo factory last November. Tuscan and slate styles are set to launch further down the line. All four will offer the same hidden panels, tempered glass three times stronger than slate or asphalt and anti-ice wiring.

If all goes to plan, the house of the future may not look too different from the house of today.

Photos via USPTO, Tesla