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Comment by tzs | Hacker News Reader

> Tesla's calculator estimates $40,500 for a roof that generates half our power needs, and should provide $20,400 worth of energy over 30-years.

This depends quite strongly on where you are. Your numbers are very close to the ones I get if I use my correct address, which is in the Puget Sound area of Washington State.

If I keep everything the same except the address, changing that to one in Merced, California, then it says I'd get $75000 worth of energy over 30 years.

PS: it looks like they try to use the address for more than just finding the location in order to estimate how much sun is available. I tried an address that I had lived at in Pasadena, California, and it did not ask me for the house size and number of floors. Instead, it did the calculation using about 6000 sq ft, which is about the size of the apartment building that is at that address. For my Seattle-area and Merced addresses, it did ask me for the house information.

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They are using Google's Project Sunroof[1] to do the modeling. The tool uses satellite images of your roof to create the estimates, and accounts for orientation, shading from trees, etc...

[1] https://www.google.com/get/sunroof

That's amazing. Just seriously amazing.

Funny enough, it was someone's side project at Google.

So was Maps, originally. This is why there's so many fans of the 20% project concept.

A distributed file sharing system (later known as the Internet) was Tim Behrners Lee's side project at CERN for a while too :)

He was only allowed to take his 20% project to 100% after his manager wrote up a justification XD

> later known as the Internet

My turn to be pedantic, I guess, but 80 and 443 are only two of many available ports. The internet is much bigger than just the web, even if lots of people never bother to look beyond their browser.

Pedantry is fine by me when accurate and done in the spirit of learning more nuance about a subject :)

An important clarification

If you ever get to go to Geneva, swing by the CERN exhibit. There's the original fileserver, complete with 'This machine is a server. DO NOT POWER DOWN!!' scrawled on tape stuck over the power button. There's also his paper describing the WWW with the feedback of his manager written across the top: "vague but interesting...".

It's kind of comforting to know that my academic and computing experiences thus far are shared both across the globe and across decades.

Haha "vague but interesting".

Isn't it amazing how big of a disconnect there is between "people who are capable of identifying/executing on big ideas" (aka Tim and his manager)....

and "the projects that businesses/agencies want their employees to do"

Especially when, in hindsight, it's anything but vague.

To be pedantic, he wrote "Vague, but exciting". See http://info.cern.ch/Proposal.html for more info.

Sorry to be a pedant but Maps is not a 20% project, it was an acquisition of a company called Where 2 Technologies. Google Earth was also an acquisition (Keyhole).

GMail however is a 20% project. :)

I'll totally use this when making my next house purchase.

What makes you think that? I'm a little skeptical because Sunroof doesn't cover my address, but I have no problem getting an estimate.

They have a link to sunroof below their estimate. Not sure what happens if you aren't covered by sunroof, but their are a ton of solar estimation tools out there that will give you a rough idea of your potential just based on lat/lon.

Random number generator, I guess. :)

Your electricity is probably a lot cheaper in Washington also and I'm assuming they have local rate information to factor in. Electricity is very expensive in California especially if you use PG&E since they use a tiered rate structure that goes from .12 - .50 cents. And very little of your usage is actually in that 12 cent tier for most people. In states like that I would imagine your solar roof could potentially pay for itself.

Seems off. Seattle gets 1/3rd the sunlight of California.

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