Shout it from the rooftop: Elon Musk goes solar in a big way
Written by Andrew Sendy
Updated March 12, 2020
4 minutes read
Image source: Tesla
Elon Musk is the Thomas Edison and Nicola Tesla of the 21st century. In the spirit of those innovators, the founder of PayPal has given us a sexy all-electric car (named in homage to Tesla); private spaceflight (perhaps one day to Mars), and now a groundbreaking innovation in home solar technology—the Solar Roof.
In 2016 Musk purchased, for $2.6 billion, solar-panel maker SolarCity. The acquisition was an attempt to fulfill one of Musk’s long-held ambitions—create a world where homeowners generate their own renewable energy.
To that end, Tesla’s brain trusts, with help from Panasonic, developed solar glass shingles that not only take the sun’s energy and turn it into electricity but are more aesthetically pleasing than a roof with conventional solar panels. Tesla’s panels, when combined with its Powerwall—a rechargeable lithium-ion battery storage system—has, in theory at least, the ability to independently power a home regardless of the time of day.
Tesla’s Solar Roof is beyond intriguing. But before placing your order, consider the answers to some of these questions.
What is a solar roof?
The first thing you notice about the Solar Roof is that it looks like an ordinary shingled roof. And therein lies its beauty. Conventional rooftop photovoltaic (PV) systems are easy to spot. They are big, cumbersome, and some people find them unattractive. For residential use, the most common panel is 65 inches by 39 inches, and the average home will need around 20 to generate enough power to meet their electricity consumption needs. The average conventional 6kW solar panel system requires around 400 square feet of roof space. There is a solar roof space calculator available on Solar-Estimate.
The Solar Roof turns that architecture on its head. In fact, it’s almost impossible to tell the difference between Tesla’s tiles and ordinary roof shingles. Its glass tiles are, according to Musk “embedded with the highest efficiency photovoltaic cells.” The tiles come in a variety of textures and colors, including terracotta, clay, and slate. The tiles are so strong, Tesla brags, that they have the highest hail, wind, and fire ratings.
“These new roofs will seamlessly and beautifully supply renewable energy to homes, battery storage systems and back into the grid creating savings for owners. When combined with Tesla Powerwall, the solar roof can power an entire home with 100 percent renewable energy,” Musk said when introducing the roof in 2016.
Although Tesla is heavily marketing the Solar Roof, it was, and is not, the first company to offer a “solar roof.” There have been various iterations over the years. One company, Suntegra, currently offers solar roof shingles and tiles, but they, like other manufacturers, don’t seem to be aesthetically pleasing as Tesla’s design and do not have the marketing presence that Tesla has.
How much does a Tesla Solar Roof cost?
According to Musk, the Solar Roof is more affordable than conventional roofs with PV systems and should pay for itself in 30 years. Consumer Reports ran the numbers and concluded that if the Solar Roof is to compete with a conventional solar roof system “it should not cost more than $24.50 per square foot.” While the magazine based that number on the estimated cost of three decades of electricity, it conceded that its formula did not include incentives and rebates. It did, however, include the cost of Tesla’s Powerwall.
For its part, Tesla says its Solar Roof prices out at $21.85 per square foot (this is an average of the non-solar active tiles and the solar active tiles0. Like standard PV systems, the photovoltaic glass tiles are installed only on a portion of the roof, while non-PV tiles cover the remaining part. Consumer Reports estimated (using its price per square foot) that a 3,000-square foot Solar Roof should cost no more than $73,500.
Of course, such numbers fluctuate depending on where you live and how much sun strikes your property. Using Tesla’s online calculator the “cash” price for a 3,000 square foot house (1,878 square foot roof) in sun-deprived western Connecticut is $61,400 and will generate $70,700 of energy over 30 years. Those numbers include a $16,400 federal tax credit, and $7,400 for one Powerwall battery. Just so you know, the Powerwall is optional.
Concurrently, a Solar Roof with the same square footage (house and roof) in sun-drenched Las Vegas will cost a homeowner around $49,800 and generate $44,700 of energy over the same 30-year period with two Powerwall batteries. For comparison, a traditional roof replacement for both locations starts at around $9,400.
If you use this calculator be forewarned: Tesla did not factor in state and local incentives, but it does determine the ratio of solar to non-solar tiles your house would need if it is to generate 100 percent energy from the sun. The calculator can also give you an idea of what your costs will be if you finance the installation.
How efficient is the Tesla Solar Roof?
While there’s no doubt the Solar Roof is soft on the eyes, they’ll only save you money if they are efficient. Solar panels are rated based on the watts they generate. The higher the wattage rating, the more power a solar module will produce. Most residential solar panels have power output ratings from 250 to 400 watts depending on size and how well the panels convert sunlight into electricity. A typical solar panel produces about 290 watts.
For its part, each 8.65-inch X 14-inch tile on the Solar Roof has two solar cells that generate a maximum of 6 watts. That means each tile can generate a maximum of 12 watts. To put it in perspective, 20 to 25 Solar Roof tiles can generate as much wattage as a full-sized solar panel. Musk has said that in some cases, 70 percent of a roof will need to be covered by solar titles, although most roofs will need only 40 percent coverage.
The upshot is that Tesla’s Solar Roof makes a lot of sense if you’re building a new house or replacing the roof on your current home. That might not be such a bad idea considering typical composition shingles have to be replaced every 15 to 30 years. Tesla’s glass tiles have a lifetime warranty, so even if they need to be replaced, the cost is on the company.
Does Tesla make other solar panels?
Yes... if you like Tesla’s engineering and commitment to a greener environment, but don’t think the Solar Roof is right for you, the company offers another option: “sleek, low-profile design” panels that “blend into your roof with integrated front skirts and no visible mounting hardware.” The panels can be hooked to a Powerwall, keeping true to Musk’s vision for an integrated and aesthetically pleasing PV system. Each panel is 325 watts. Tesla says the panels “exceed industry standards for durability and lifespan.”