April 19, 2017

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Crossposted the Davis Enterprise page A10

This column is primarily about rooftop solar in Yolo County, but before we get to that, there have been at least two interesting announcements from the tech world recently in terms of the future for rooftop solar. And, of course, two of the biggest names in tech are the ones making the announcements.

Solar roof tiles by Tesla

First, Tesla announced in late March that it would begin taking orders for its solar roof tiles in April. (Disclosure: A member of my family works for Tesla on this project, but I gotta say, I’d be excited about this development no matter what.)

Many people have complained that solar panels are unattractive and this is one reason they don’t want them on their roof. I’ve never really understood that sentiment but I know it is real for many people.

Anyway, according to the announcement, Tesla will begin offering four styles in mid-2017: three that look a lot like the asphalt tiles on my roof, and one that approximates a Spanish or Italian style. The company claims that the cost of the tiles will be less than the cost of traditional roof tiles, once the energy savings from having solar on your roof are factored in.

You can find more information (and pictures) at www.tesla.com/solar.

Google calculates solar potential

Second, Google announced that its Project Sunroof now covers all 50 states. This project is essentially an aerial mapping of the entire country, including some 60 million homes. Anyone can enter their address into this database and Project Sunroof will use a combination of Google Earth imagery, the shape of your roof, and local weather patterns to evaluate your potential for rooftop solar.

I did this for our house, and in two seconds Project Sunroof told me we have about 600 square feet of available space on the roof 1,836 hours of usable sunlight over the course of a year, and we could save about $4,000 over the course of a 20-year lease.

Of course, there are lots of assumptions built into these estimates so Project Sunroof lets you “fine-tune” the estimate. The website has a slider that you can set anywhere between $0 and $500 for your average monthly electric bill, and this setting automatically adjusts the recommended square footage for your system, as well as the percentage of your electric bill you might expect to cover with your solar system. The website also adjusts estimates according to whether you lease, take out a loan, or purchase your system.

I’m not sure how accurate it is, but its pretty slick and, if you are inspired, it follows up with a list of solar providers (though I notice these are mostly big, national companies and the list does not include some of our home-grown installers) and includes the opportunity to right then and there send a note to selected installers letting them know you are interested.

To try it yourself, google “Google Project Solar.”

Yolo County cities moving forward on renewables

So, on to the topic of solar on rooftops in Yolo County. I’ve been trying for the past couple of years to obtain data from each city in the county, as well as the county itself, as to the number of systems installed in a calendar year and the total kWh capacity associated with those systems.

Starting with Davis, in 2010 the City Council set a goal of producing, by 2015, 5 percent of the peak electricity used in our town from rooftop or local systems. It was calculated that this would require 1,733 installations. In a report last May to the council, staff indicated that the city had exceeded that goal, with a total of 2,360 systems.

In response, the council set new goals for the year 2020 and challenged the community to about double the number of residential systems to 4,500, resulting in rooftop solar on roughly half the of all single-family homes in Davis. The year 2016 got us off to a flying start with installation of 502 residential rooftop systems, putting us on track to reach the 2020 goal.

So how is the rest of the county doing? The city of Woodland also set ambitious goals for 2020: obtain 40 MW of electricity from renewable sources and install solar PV on 5,000 homes, Whereas Davis has seen a substantial number of installations for nearly a decade, solar PV just recently took off in Woodland, with 46 percent of the total number from 2005 to 2015 coming from systems installed in 2015.

But they are quickly making up for it, and in 2016 they added 577 residential installations. Adding in commercial and municipal installations, the city totaled over 5 megawatts of capacity in that one year alone.

The city of West Sacramento is also booming in terms of PV systems, with 406 residential installations in 2016 with an estimated total capacity of a little over 2 MW. Add in 14 commercial and four multi-family installations with about 8 MW and the total comes to about 10 MW, a pretty amazing total for a single year.

I wasn’t able to get information for Winters or unincorporated Yolo County but, all in all, little Yolo County is going gangbusters on renewable energy.

— John Mott-Smith is a resident of Davis; his column is published on the first and third Wednesday of each month. Send comments to johnmottsmith@comcast.net