You may have seen one of the articles out this week headlined something like “Tesla’s solar roof is cheaper than a normal roof,” that went on to claim that Tesla’s baseline $21.85 per square foot price is 20 percent less than a “normal” roof — even before you account for the electricity savings. As someone who owns a house that needs a new roof, this got my attention for two reasons. First, I’d love to extend our solar panels to cover our entire roof, so if I could save money at the same time, what a deal! Second, the comparison didn’t sound right. Asphalt roofs are relatively inexpensive, often under $10 per square foot all in.
No, the Tesla Solar Roof Isn’t a Free Lunch
Digging through the stories to find the original source of the comparison, it is a Consumer Reports article that is actually quite clear in its analysis. For its benchmark 3,000-square-foot roof (about average for the US), it lists cost estimates of $16,000 for clay tile, $20,000 for asphalt, and $45,000 for slate. They guessed that Tesla might cost around $70,000 (actual pricing turns out to be a bit less, so maybe $65,000). In raw terms that puts the Tesla roof at a solid multiple of the cost for any typical material — even slate — if you don’t factor in the electricity savings.
You can get a ballpark estimate for the cost and savings your new roof will generate by simply typing your street address into Tesla’s Solar Roof calculator. You’ll likely see that the upfront outlay (assuming you choose the Cash option) will be substantially larger than for a traditional roof — even factoring in the tax credit. However, at least if you are in an area that gets good sun much of the year, the calculator will give you some rosy numbers for the amount returned in energy savings over the next 30 years. Tesla uses a simplified interface to Google’s Project Sunroof, so you might also want to head directly to the Google site to play with various assumptions like loan interest rates and net present value calculations for your potential savings.
Of course the other unknown is about the product and installation, since this is new technology and a new line of business for Tesla. If you have the cash or are willing to finance the installation and let it pay back over time the numbers look great. But personally I’m waiting until some early adopters actually go through the process and write about their experiences before I take the plunge.