The cost question: Barry Cinnamon on Tesla’s Solar Roof


pv magazine: Tesla unveiled its new Solar Roof product on last Friday. In broad strokes, what are your initial thoughts on this product?

Barry Cinnamon: BIPV is the holy grail for rooftop solar installations. I commend Tesla for launching such an innovative product in this category. From what I have seen so far, Tesla has done an admirable job of improving the aesthetics of solar shingles, certainly much better than any similar products I have installed or evaluated over the past 15 years. However, without more detail on their solar shingle costs and UL certifications it is difficult to evaluate the ultimate potential of this product.

spice_solar_barry_cinnamon_wordpresspv magazine: Solar roofing shingles have been difficult to make money on for several companies, including Dow. What in your mind are the biggest obstacles to making this concept work commercially?

Cinnamon: Ultimately, the biggest obstacle relates to total installed cost of solar shingles. Hopefully Tesla can overcome some of the following limitations of these solar shingle products:

  • High cost of shingles on a per watt basis
    Since shingles run hotter, power output is typically less than conventional modules (effectively increasing per watt cost)
  • Uneven shingle surfaces are not optimized to capture incident sunlight, reducing efficiency (effectively increasing per watt cost)
  • Each shingle (or group of shingles) needs a pair of wire connections. These connections are expensive to purchase and install.
  • “Dummy” shingles are needed to meet fire setbacks (typically 3′ around roof), and to install in shaded areas

The majority of new installations use module electronics, both to improve performance and meet NEC codes (rapid shutdown, arc fault, etc.). Systems using solar shingles will need these capabilities.

Installation time is likely to be longer for solar shingles since there are more shingles, more wiring, possible extra underlayment to meet Class A requirements, and more design time to determine exactly where PV shingles and Dummy shingles are placed (all increasing costs).

Since most other shingle products have been removed from the market, there are questions about long term reliability and warranty performance.

PV installers are generally not roofers or electricians. Finding a contractor that can combine these capabilities is important.

pv magazine: Given its scale and industry presence, do you think that Tesla/SolarCity will be able to succeed where other companies have failed? Why or why not?

Cinnamon: Tesla certainly has the resources to overcome many of these problems. In addition, SolarCity does have the ability to meld the roofing and electrical skills necessary – so they can address the sales channel issues. Once we know the price of the shingles on a per watt basis, the installation characteristics of the shingles, and the exact certifications (1703, 2703, etc) it will be much easier to determine the their potential for success.

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