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Solar Roof

tesla.com

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Re: Solar Roof

#401

Post by tomaskafka »

def- wrote: post #393
tomaskafka wrote: post #389

Earlier quoted context omitted.

My electric costs are 0.035 USD/kWh here in Europe (Czech Republic). Wth is wrong with the USA? It seems like you're getting screwed over everything. 10x electricity, 100x healthcare and education - is US market really just a bunch of colluding monopolies?

I couldn't quite believe your numbers, and couldn't find any confirmation for them: http://ec.europa.eu/eurostat/statistics-explained/images/4/4... http://ec.europa.eu/eurostat/statistics-explained/index.php/...

Hm, that seems unusually high, really wonder where these stats come from. Is every eurostat statistic distorted like that?

Here's a chart of energy prices on a Prague energy exchange, currently it's about 30 EUR/MWh = 0.032 USD/kWh. I pay a bit more than that (incl. distribution) with a good tarif (low cost broker), but even conservative people I know who don't renegotiate energy prices get about 0.06 USD/kWh incl. all distribution fees.

That said, electric distribution network in our country is probably underinvested. Is the premium you're paying in US based on distribution network cost?

http://www.tzb-info.cz/ceny-paliv-a-energii

Re: Solar Roof

#402

Post by MagnumOpus »

pedrocr wrote: post #44
atourgates wrote: post #31

Earlier quoted context omitted.

I don't really see the selling point, or value here. 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. Add in a PowerWall and federal tax credit, and I'm still losing $15,400 over 30-years. If I put that same $40,000 in an index fund that got the stock market's historical 7% average, and waited 30 years, I'd have $308,000. To…

>If I put that same $40,000 in an index fund that got the stock market's historical 7% average, and waited 30 years, I'd have $308,000. Are you doing the math all in present dollars? Because the return is 7% after inflation but >10% before. So you'd have >500.000 in 2047 dollars. In this case it's important to do that adjustment because you're doing an investment upfront for payoffs over 30 years so the value of mone…

If you expect either 7% real returns or 10% nominal returns from the stock markets over the next few decades, you're gonna have a bad time - mostly because real interest rates in the 21st century are much lower than in the second half of the 20th.

Current expert thinking is that there is a 4% equity risk premium over cash interest rates. Current cash rates are 1% nominal or -1% real. If you are an optimist like the Fed, cash rates will rise to 3% over the long term - which gets you to 7% nominal/5% real at best.

Re: Solar Roof

#403

Post by dagw »

marcosdumay wrote: post #59
IvanK_net wrote: post #45

I have always been a huge fan of a quick transition to sustainable energy sources. There is just one little thing I don't understand. Why they expect people to make electricity at their homes? You can buy a little piece of land in a dessert, put solar panels there and distribute the electricity to other places. And you don't have to climb on any roof during the installation or the maintenance. It is not profitable to…

It's because local photovoltaics can save a lot of infrastructure and can require nearly no labor. You don't buy cold air piped from across the city, you make it locally. Why?

You don't buy cold air piped from across the city, you make it locally. Why?

In Sweden it is quite common to pipe hot air (and to a lesser extent cold air) across the city rather than each house making it locally. Once of have the basic infrastructure in place it is a lot cheaper and more efficient.

Re: Solar Roof

#404

Post by ZeroGravitas »

kristofferR wrote: post #391
jpatokal wrote: post #248

Earlier quoted context omitted.

Why so? California's climate is pretty optimal for solar generation and there's a lot of desert waiting to be covered in solar panels. Solar is not going to have a similar impact on (say) Ireland in the next 30 years.

More solar will likely result in higher grid energy prices, since people will buy a lot less energy while the grid costs the same to maintain.

Solar can also reduce grid costs, by e.g. shaving the yearly peak power demand, which is usually a summer afternoon so it's not clear cut.

Probably the bigger impact is bad incentives for the people building the grid, who are often able to do what they like and get a guaranteed percentage return on top, which pushes them to spend more than they need to. This has been particularly pronounced in Australia I believe.

Re: Solar Roof

#405

Post by ZeroGravitas »

Retric wrote: post #129
blakesterz wrote: post #2

Yikes. I just signed a contract for a new roof here last month, it's going to cost about $12k. Just did the estimate for the Tesla Solar roof... $80,300, so $87k if I want the battery too. I can barely afford the $12 right now, the $80 is just so far over it's not even close, even with how much I save over the years in electricity. That being said, I love these things, so hoping it gets cheaper in the coming years.

It depends on your roof orientation and your location so ROI has a huge range. For example if you don't have a southern facing roof then this is going to be a terrible investment. However, this is also a home improvement which means a low interest loan which has many tax advantages, remember you pay your electric bill with after tax money but you pay interest on a home loan with pre tax money. Further electricity cos…

South facing roofs aren't essential to solar. East-West layouts can spread the energy production out through the day and work out better overall depending on various factors such as how much you make from selling excess to the grid.

Re: Solar Roof

#406

Post by remael »

NamTaf wrote: post #274
salesguy222 wrote: post #254

Earlier quoted context omitted.

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

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 shar…

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

Re: Solar Roof

#407

Post by ZeroGravitas »

rhino369 wrote: post #281
boucher wrote: post #205

Earlier quoted context omitted.

When home solar installations send excess power to the grid, they also do it in the middle of the day, when wholesale electricity prices are at their highest.

For now. When 10% of people have panels, that won't be true anymore.

So cheaper prices at the time of most usage (and previously highest cost to generate or consume) which is yet another positive externality of solar power.

Re: Solar Roof

#408

Post by Retric »

ZeroGravitas wrote: post #405
Retric wrote: post #129

Earlier quoted context omitted.

It depends on your roof orientation and your location so ROI has a huge range. For example if you don't have a southern facing roof then this is going to be a terrible investment. However, this is also a home improvement which means a low interest loan which has many tax advantages, remember you pay your electric bill with after tax money but you pay interest on a home loan with pre tax money. Further electricity cos…

South facing roofs aren't essential to solar. East-West layouts can spread the energy production out through the day and work out better overall depending on various factors such as how much you make from selling excess to the grid.

These are tiles that sit flush with your roof, east west roofs act like zero tilt panels which provide less power everywhere in the US and thus lower efficiency. Granted if it's cheap enough that's not a deal breaker, but it's always going to impact ROI.

Re: Solar Roof

#409

Post by averagewall »

Shinkei wrote: post #373
averagewall wrote: post #367

Earlier quoted context omitted.

Why does every climate change story have someone spreading the same false information? Climate change isn't a threat to the human race. Inventing extreme ideas entrenches opposition and gives them valid reasons to say "you're wrong and I won't do anything to help". If you really believe that, then it's an unconventional idea that deserves references.

Read away: https://en.wikipedia.org/wiki/Global_warming#Observed_and_ex...

I don't see anything in there related to the extinction of humans. That's what the OP was concerned about.

Re: Solar Roof

#410

Post by pedrocr »

MagnumOpus wrote: post #402
pedrocr wrote: post #44

Earlier quoted context omitted.

>If I put that same $40,000 in an index fund that got the stock market's historical 7% average, and waited 30 years, I'd have $308,000. Are you doing the math all in present dollars? Because the return is 7% after inflation but >10% before. So you'd have >500.000 in 2047 dollars. In this case it's important to do that adjustment because you're doing an investment upfront for payoffs over 30 years so the value of mone…

If you expect either 7% real returns or 10% nominal returns from the stock markets over the next few decades, you're gonna have a bad time - mostly because real interest rates in the 21st century are much lower than in the second half of the 20th. Current expert thinking is that there is a 4% equity risk premium over cash interest rates. Current cash rates are 1% nominal or -1% real. If you are an optimist like the F…

I wasn't making a prediction on future returns just commenting on the historical returns used. For this case 5-7% should be more than enough as a comparison to the Tesla investment anyway. I'm curious about those risk premium estimates though. Any pointers or sources on where to read more about them?
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