Plastics Play Starring Role in Elon Musk’s New Solar Roofs

Outside home at dusk

The promise of rooftop solar energy is enticing: harnessing the sun’s rays to supply unlimited residential energy. Maybe even to produce excess energy for electric vehicles.

The benefits touted by residential solar advocates are many: cheaper energy, increased home value, reduced reliance on traditional sources of energy, reduced pollution, lighter environmental footprint…

Residential solar energy is on the upswing, breaking growth records in three of the past four years and up 19 percent in 2016 over 2015. Both technological and financial efficiencies are improving.

But obstacles remain.

Even though costs are declining, they remain an obstacle to widespread use of solar energy. In a new or old house, homeowners must pay for a conventional roofing system. Then they also must pay to install solar panels. So their big question is about return on investment. When will my reduced energy costs pay for the costs of installing solar panels?

Another issue is aesthetics. The profile of a home’s roof is one of its defining attributes. Some homeowners spend significant sums beautifying roofs, even creating the look of Tuscan villas or French provincial chalets, and they can be reluctant to cover them up.

So … if a roof could produce solar energy, be aesthetically pleasing, and diminish or even alleviate the added cost of solar panels, wouldn’t that be quite a breakthrough?

That’s pretty much what SolarCity, acquired in 2016 by Elon Musk’s Tesla, says it will do.

And plastics play a starring role.

Company press and marketing materials provide some information about how the new solar tiles, scheduled to start production mid-2017 in Buffalo, NY, will be made. The tiles will consist of “extremely strong tempered glass” that “can withstand three times the force of standard roofing tiles.” A video on the company’s web site shows a falling 1.2-pound steel ball demolishing concrete, terra cotta, and slate roofing tiles… and bouncing off the glass tile. Embedded below the glass are “the highest efficiency photovoltaic cells.”

But it’s the material between the glass and solar cells that represents a real breakthrough. Described as “colored louver film” that “allows the cells to blend into the roof while minimizing solar efficiency loss,” this layer allows the sun’s energy to reach the cells while appearing from the ground level to be attractive roofing. Homeowners will see nothing but Tuscan terracotta, slate, smooth, or textured roofing tiles.

So… homeowners would buy a solar roof. Not a roof plus solar panels.

Just what is this “colored louver film” and how does it work?

While the company has provided few details, press reports have shed some light. Fortune magazine reported that the film acts sort of like a venetian blind, allowing light through its “micro-louvers.”

The plastic film was developed for Tesla by 3M, according to Fortune’s interview with 3M corporate scientist Andrew Ouderkirk. “‘Its like a micro venetian blind,’ said Ouderkirk, explaining that “it works in a similar manner to a privacy film that goes on a computer screen that blocks anyone from the side from trying to look at the screen.”

Musk described the film as a “very durable plastic.” He said that the tiles would use “hydrographic coloring” (a common printing process) and that the micro-louvers on the film would make possible the roof tile colors and patterns.

As for cost effectiveness, Musk claimed the solar roof was likely to cost less than a normal roof… even before savings from the energy bill. “Electricity is just a bonus.”

SolarCity is marketing its new solar roof along with Tesla’s electric cars and home energy storage battery called Powerwall. Energy captured by the solar roof would be used in the home, and excess energy would be stored for later home use and to charge the electric car batteries.

It’s important to note that many past claims of solar energy’s efficiencies have not rung true. Until this solar roof hits the market later this year, such claims of course cannot be confirmed.

But if successful, the new solar roofs would overcome significant obstacles and make rooftop solar considerably more promising.

Plus aesthetically pleasing … thanks to the starring role of plastics.