Their algorithm needs some work.
They correctly identified that half of my roof faces due south at a good angle for solar panels, but they still said it "may not be ideal for solar panels." They are wrong,
I have solar panels and they are awesome! And profitable!
Google's project sunroof estimates that I have 511 square feet of available space, which is pretty darn close to the 492 sqft of panels I actually have. You lose some around the edges because you can't put panels all the way out to the very edge of your roof. Some local regulation about fireman needing to axe through the shingles.
Project sunroof also estimates that those 511 sqft of space will hold 388 sqft of panels producing 5.5 kW of power. I actually have 492 sqft of panels producing more like 7.5 kW. Their ratio must be assuming you use lower efficiency panels than I have. (mine are 270 W per panel, but newer ones are over 300 W.)
Project sunroof is apparently unaware of the local state solar production incentive program that makes my panels so profitable. They think my panels should be $16k up front, and total $2k out of pocket costs over 20 years. By my calculations, my panels instead cost me $23k up front after incentives, then the state pays me $5k/year for the first six years (totally paying for the panels and installation), for a total 20 year cost of negative $9k. Plus they save me something less than a thousand dollars per year because I no longer pay for electricity, so let's call the total 20 year cost savings more like $25k. Project sunroof is off by a factor of ten, and they think panels will
cost me money while they are instead currently
saving me boatloads of money.
Project sunroof also thinks their proposed panels would cover 54% of my household's electricity use. I don't know how they arrive at this number, but they clearly aren't accounting for mustachian power consumption levels. My panels provide more than 100% of my family's annual power use, and that's INCLUDING charging our 100% electric car with about half of our solar production. So I don't buy much gasoline, either. Win!
