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A dark cloud is hovering over Tesla's solar business.

A study by research firm Wood Mackenzie found that Tesla has installed a total of 3,000 Solar Roofs -- its stylish flagship alternative to solar panels -- in the US. This puts Tesla way behind the schedule the company set for itself in 2019 of installing 1,000 per week by 2020. Sure, there was a fairly big and communicable global blip in that timeline, but we're now four years down the line and Tesla isn't known for sticking to its own production deadlines.

Make Roofs While The Sun Shines

Tesla first unveiled its Solar Roof product in 2016. The idea is that rather than bolting solar panels on top of your existing roof, Tesla installs a brand new roof made up of photovoltaic tiles to the top of your house. CEO Elon Musk pulled out a prototype tile at the unveiling, which The Fast Company later reported did not actually work yet, but in the intervening years, Tesla has made an actual, working product. Even Musk fakes it until he makes it.

The wider solar industry has made significant gains in that timeframe, and The Wall Street Journal reported Thursday that renewable energy consumption as a whole is driving down the price of coal. In terms of the residential solar market, however, Tesla Energy (the company's solar division) has lost some of its power:

  • Tesla Energy was born in 2016 when Tesla acquired SolarCity, a company run by Musk's cousins, for $2.6 billion. Prior to the acquisition, SolarCity had been the top installer of residential solar panels in the US.
  • It lost the top spot to rivals Sunrun and Vivint when they merged in October 2020, solidifying their combined market share.

Solar shingles remain a tiny sliver of the overall market, and it's not a huge mystery why. "They're difficult and expensive to make, they require more specialized labor to install, and they can cost tens of thousands more than traditional rooftop panels," Nick Liberati, senior communication manager at price comparison site EnergySage, told The Daily Upside. "On top of that, they're typically significantly less efficient than solar panels."

Where We're Going We Don't Need Roofs: Residential buildings are far from the only place to pop in a solar panel. A paper published this month in Nature Sustainability made the case for placing floating solar panel farms in reservoirs, lovingly nicknamed "floatovoltaics." The paper estimates floating solar cells could generate 40% of the world's electricity. Not too shabby.