Google's Project Sunroof Tells You How Well Solar Would Work On Your Roof

An anonymous reader writes: Google's Project Sunroof aims to make the task of installing solar panels easier by providing financial advice and stats on what solar energy could do for you. The project is only available in San Francisco, Boston, and Fresno for now. Techcrunch reports: "To get started, you simply plug in your address and some data about your monthly electricity bill, and the tool will tell you what the recommended solar installation size is and how much it would cost to buy or lease the hardware. In case you want to go ahead with a solar install, the tool also lets you reach out to local solar providers. Google says these listings are sponsored, so chances are it'll get a bit of a kickback when it generates a sales lead for these companies."

Comments

Not available yet...

[Firethorn]

Darn it: "Sorry, Project Sunroof hasn't reached this address yet."

Can't say much about it then.

Re:Not available yet...

[thinkwaitfast]

Try pvwatts. It's very accurate in my experience.

http://pvwatts.nrel.gov/

Strange limitations

[pla]

Annual insolation, even after considering weather, counts as a well-documented stat across the entire US. Why would they limit this to just a few key cities?

Google says these listings are sponsored, so chances are it'll get a bit of a kickback when it generates a sales lead for these companies.

Oh, riiight! "We don't have any partners outside those cities yet, so the rest of you can go fuck yourselves". Got it.

Re:Strange limitations

[bondsbw]

If you aren't willing to pay for alternative energy, then don't be surprised when you don't get it. Google helps advance that cause and all you can do is complain that they are a business.

Re:Strange limitations

[Mr D from 63]

Local, state and federal subsides vary drastically only a few miles apart. That database would tax googles servers.

That's right. The subsidies are required to make this look good. It is, after all, sponsored by installers. The calculator naturally assumes everything is optimum, and doesn't get very detailed when it comes to additional expenses that may be incurred during installation. It also assumes 2.2% per year rate increases, which is not necessarily going to happen.

I did a spot check on their Redwood Ca numbers. They calculate using solar insolation equivalent to 5 hrs/day, but real numbers are about 4.7 hrs/day.

Re:Strange limitations

[swillden]

Annual insolation, even after considering weather, counts as a well-documented stat across the entire US. Why would they limit this to just a few key cities?

Because this provides dramatically more detail than regional average insolation. It tells you how much insolation each portion of your roof receives, accounting for local geography, flora and other buildings. That takes some moderately-detailed 3D models and heavy number crunching. The 3D models come from Google's project to build 3D models of all population centers using low-flying aircraft with angled cameras, so Sunroof will only be available in regions where the models are available (zoom in in Google Maps in your area to see if it's already 3D-ifiied) and even then it will take time to crunch all the data.

Might as well ...

[PPH]

... just contact a local system installer. The insolation data for a particular region is already known and publicly available. What will affect your particular system are things like local shading, roof pitch and orientation and cost of installation as affected by your house and lot particulars. Local installers will also be familiar with your utilities solar programs.

Re:Might as well ...

[Anonymous Coward]

Yeah, but the most important number is the cost of electricity, which is _assumed_ to hold constant, rather than go up in price. Given the shit to natural gas which is historically cheap right now, and the difficulty of going back to coal for baseload, that's not a very good assumption on balance.

We opted not to get solar, but we live in San Francisco. Our home doesn't even have an A/C, just an old furnace. The one thing that almost persuaded us was that if we got solar this year we'd be locked into a favorable, 20-year contract with PG&E which would require them to purchase our excess capacity at market prices. That program will end sometime this year or next, when the number of participants hits the statutory cap.

Here in California electricity prices are relatively low. They've remained constant for almost a decade, and are just beginning their inexorable rise as PG&E begins the decades-long replacement of ancient infrastructure. If we lived outside San Francisco, especially in South Bay or East Bay in a home with A/C, we'd get solar without hesitation.

As we live in SF, and our biggest expense is for gas for the furnace during the winters and spring, the risk just wasn't worth it. Our average electricity bill is less than $75/month, and our peak electricity use in the winter is at night (when we use a space heater upstairs). So our exposure to increased prices isn't that great. Our payback at current prices was in 20 years. However, it would have increased the value of our home substantially (because of the "eco" factor, because of the PG&E lock-in), so including increased equity the payback would have been almost immediate. But we have other, higher priority home improvements to worry about right now. Solar installation contractors are almost universally shady; it's exceptionally difficult to find a reputable one. I just didn't like the idea them causing damage to our roof, however minimal the risk, given our current budget.

Re:This already Exists

[hawguy]

There is already a the PVWatts calculator at on NREL's website. You input your location, the type and placement of the solar panels and it tells you how much power to expect based on local weather measurements. Since these are the people gathering the data, I can't imagine google's project does anything than access this same database.

http://pvwatts.nrel.gov/

The NREL site just looks at location and weather to estimate solar availability -- The Google site attempts to calculate usable roof area and take into account shading from nearby trees and other structures.

Real numbers

[FlyHelicopters]

It will cost, give or take, about $40K to install a 10 kilowatt system on my home.

Returning the 30% federal tax credit back to me puts me at a cost of $28K.

Based on my location in Texas and my current utility rate (total cost) and that I have net-metering, I'll save about $1,400 a year in electricity with such a system.

That puts me at an even 20 year payback period. Now, in fairness, electric rates are not likely to stay the same, adding solar does add something to my home's value, so there is that.

Lets say that electric rates will rise with the rate of inflation, which the government currently says is nearly zero, but will probably rise, then add something to the value of my home, and you get about a 12 year payback period, if you use numbers that favor solar and 17 years if you don't.

What those numbers DON'T take into account is the loss of net-metering, which is a real risk. If too many people go to solar, it will have to go away. If everyone installed solar on their roof and ended up with no electric bill, the power companies would go out of business. Clearly they would actually go out of business long before then, maybe at 20%. You can talk about batteries all you want, but the reality is they likely will get lawmakers to remove net-metering before then.

Regardless, it is a terrible investment, it makes no sense whatsoever from a financial point of view, at least for me. If you pay more than I do for power, then it might make sense for you. I have family in Australia who recently installed solar because they pay more than 25 cents per kWh, so the numbers are quite different there.