We were on the Metro Denver Green Homes Tour last Saturday. It occurs each year on the first Saturday of October which is the National Solar tour day. We were a site to see the Tesla Solar roof and our Powerwalls as well as other energy saving ideas that helped us earn LEED Platinum certification.
Visitors asked us if the roof was worth the money it cost. I explained yes by asking what else is this expensive? Typically a higher end new car costs in the vicinity of our roof but our roof pays us back for the next 25 years at least while the new car just costs more money.
My second consideration was that our roof was 17 years old and had been through several hailstorms. It was time to replace the roof. A typical shingle roof would have cost say $8 a square foot, some are cheaper some more expensive. But a class 4 hailproof dimensional shingle would cost about $15 a square foot and solar panels cost about $10 a square foot, although panels are typically rated by watts not size. The Tesla roof is made of tempered glass tiles and designed to look like slate. An even higher end slate roof would cost $20-$25 per square foot and up. The cost for both a new high quality roof and 16 kw of panels would add up quickly.
Higher wattage panels are larger than lower wattage panels but take better advantage of space available. They require a long lasting roof installed under them or you risk having to remove the panels, install a new roof, and have the panels re-installed on the new roof. Tesla tiles each cost more for the solar than their plain roof tiles, but the average cost per square foot was estimated at $20 to install them. Installation on a complex roof might cost more.
Tesla solar roof tiles are rated as 72.67 watts. The tiles are fewer watts per square foot than the 400 watt panels but not by much. I can’t install solar panels to the extent that they can be integrated on our roof. They can’t be mounted all the way to the peak or around protrusions. Plus estimates of the actual cost per solar watt installed is about $1.80 for the Tesla roof tiles and the typical installed panel cost per watt is currently about $3 in Colorado. So it makes good sense to install as many of the solar tiles as possible. In Colorado that’s up to two times the yearly amount consumed by the customer for grid-tied systems. The solar tiles unlike the filler tiles, are not only an excellent roof but produce power so are much more valuable. A large area of our south facing roof is flat or nearly flat shown as light gray in the diagram. The garage roof points south and a small area points east but the rest of the roof faces north.
Our roof is slightly over 16,000 watts. it includes all the wiring and inverters to run our system. It would take 40 400 watt panels costing about $48,000 without the extra equipment to get that much power! So the articles that I read that say you can get cheaper solar and a new roof do not seem to make financial sense. Certainly you cannot get a slate quality roof and a full solar grid-tied system any cheaper.
I may have been one of the lucky ones who actually had a Tesla solar roof installed. During my research for this article I read that installation has been halted. No official reason but the guess is a shortage of the solar glass tiles and a booming business in panel installs. Our roof is version 3 and an updated version 3.5 is being developed.
My conclusion is that there is resistance to new ideas. Only when early adopters, and like the Tesla cars they are consumers with more money, start to spend on a new idea does it become mainstream. When we first bought a Honda hybrid in 2002 the articles about the cars discouraged purchasing the new technology. No shops can repair them, never save in gas enough for the additional cost, technology not sufficiently proven. Yet the same writers thought nothing of recommending the latest expensive bells and whistles on non-hybrid cars. Paying for those fancy technologies were what they knew. Luckily the car buying public ignored them and the cars became popular. I suspect the same will happen with solar roofs.