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Solar Roof

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Re: Solar Roof

#161

Post by ch4ch4 »

11thEarlOfMar wrote: post #138

In modeling whether this makes sense, I looked at my annual electricity bill, which comes in at about $1,800/year. That's not enough savings opportunity to justify a ~$70,000 roof+batteries. However, when I add 2 electric cars, the savings nearly triple [0]. Instead of buying gasoline, I'll be paying for electricity. At $5,400/year, spending $70,000 starts to make some sense. On the other hand, if I put up ugly panel…

In your calculation, $10/kWh is a bit high... the national average is $0.12/kWh

Re: Solar Roof

#162

Post by deegles »

11thEarlOfMar wrote: post #138

In modeling whether this makes sense, I looked at my annual electricity bill, which comes in at about $1,800/year. That's not enough savings opportunity to justify a ~$70,000 roof+batteries. However, when I add 2 electric cars, the savings nearly triple [0]. Instead of buying gasoline, I'll be paying for electricity. At $5,400/year, spending $70,000 starts to make some sense. On the other hand, if I put up ugly panel…

What's your goal though? If it's just to save money then it makes more sense to drive a beater gasoline car.

If the goal is to help the environment, it's probably still better to buy a beater gas car and buy carbon credits with the difference. Also there are tons of other things you can do like downsizing, eating less meat, biking to work, etc.

Re: Solar Roof

#164

Post by gnopgnip »

azeirah wrote: post #16
SirLJ wrote: post #8

Tesla acquired SolarCity in November in a deal worth $2.1 billion. At the event, Musk said Tesla's roof would price competitively with normal roofs and could even cost less. "It's looking quite promising that a solar roof will actually cost less than a normal roof before you even take the value of electricity into account," Musk said at the event. "So the basic proposition would be: Would you like a roof that looks b…

I'm 21, thus I have no idea what roofs normally cost. I assume they're very very heavily below ~80k? For a "regular" house, what would a roof cost? 4k? 10k? 500?

A 2000 sq ft tile roof would cost about $20k in a large city. The same roof with asphalt shingles would cost about $8000. The warranty difference from 10 to 30 years, the slope and shape of the roof, and local disposal and labor differences will all affect the price.

Re: Solar Roof

#165

Post by RodericDay »

deegles wrote: post #162
11thEarlOfMar wrote: post #138

In modeling whether this makes sense, I looked at my annual electricity bill, which comes in at about $1,800/year. That's not enough savings opportunity to justify a ~$70,000 roof+batteries. However, when I add 2 electric cars, the savings nearly triple [0]. Instead of buying gasoline, I'll be paying for electricity. At $5,400/year, spending $70,000 starts to make some sense. On the other hand, if I put up ugly panel…

What's your goal though? If it's just to save money then it makes more sense to drive a beater gasoline car. If the goal is to help the environment, it's probably still better to buy a beater gas car and buy carbon credits with the difference. Also there are tons of other things you can do like downsizing, eating less meat, biking to work, etc.

Tesla's entire offering is trickle-down environmentalism.

Re: Solar Roof

#166

Post by EdwardMSmith »

azeirah wrote: post #16
SirLJ wrote: post #8

Tesla acquired SolarCity in November in a deal worth $2.1 billion. At the event, Musk said Tesla's roof would price competitively with normal roofs and could even cost less. "It's looking quite promising that a solar roof will actually cost less than a normal roof before you even take the value of electricity into account," Musk said at the event. "So the basic proposition would be: Would you like a roof that looks b…

I'm 21, thus I have no idea what roofs normally cost. I assume they're very very heavily below ~80k? For a "regular" house, what would a roof cost? 4k? 10k? 500?

I can give a quote on the sort of roof materials this competes with.

I had to have the tile roof on my 1923 house replaced due to a massive hail storm (in roughly 2006). The house's footprint is about 1000 square feet, so not entirely sure of the actual roof area (probably about 1200 sq/ft), but the bill for removal of the old roof, some repairs to the sheathing, and replacement with new tiles was about $55,000 - materials (Ludowici tiles) and labor.

The solar roof quote for our roof from the Telsa website was about $48,000. So, in my case it would have been competitive.

My new tile roof has a 75 year warranty, btw.

Re: Solar Roof

#167

Post by stcredzero »

vkou wrote: post #115
ctdonath wrote: post #42

People keep overlooking the objective value of not relying on "grid" power sources. Power goes off, your system keeps going. Gasoline supply stops (I've seen that a few times), you can just power your car at home. Your system fails, grid is likely still up to cover. Supply-and-demand takes a sharp turn when supply is actually limited and can/does run out . At that point, having pre-paid for your own uninterrupted off…

If your city's electricity and gasoline supplies have stopped for any appreciable length of time, you will have far more serious problems then 'I've only got 120 miles of gas in my tank.'

If your city's electricity and gasoline supplies have stopped for any appreciable length of time,

I've been in exactly this situation after Hurricane Ike. I was driving a 1995 Mercedes E300 diesel on biodiesel. Since there was only 1 place to buy biodiesel, I had developed a habit of filling my tank, plus 2 5 gallon diesel fuel cans, so I had a stockpile.

you will have far more serious problems then 'I've only got 120 miles of gas in my tank.'

When the city is in a state like this, the filling stations are closed. Yes, it was very nice to know I had a "stockpile" of ~400 miles of driving range! Those "more serious problems" mean that those miles in your tank are extra valuable!

Re: Solar Roof

#168

Post by fpgaminer »

mavhc wrote: post #65
fpgaminer wrote: post #35

I'm so absolutely excited for solar power. Tesla's Solar Roof, their PowerWall batteries, electric cars. It's all just painting such a bright future. Certainly Tesla has no monopoly on it, but they've made it sexy and are pushing the bleeding edge forward. Props to them. We recently signed a contract to do an installation on our house (with a local contractor, not SolarCity). It can't happen soon enough! We'll have e…

Going off grid means you need a lot more batteries, which need materials and energy to make. Switching from gas to electricity for heating is a bad idea if there's still coal power stations in use, if you're not selling your excess power to the grid, they're going to turn on that coal power plant again. Sharing power is a much better idea than trying to store it in batteries, unless those batteries are in a car

> Switching from gas to electricity for heating is a bad idea if there's still coal power stations in use

You misunderstand. Our solar installation will be expanded to cover the appliances. We'll be 100% off-grid.

> Going off grid means you need a lot more batteries

We only need 3 PowerWalls to cover all our needs (~1 for our needs now, 3 for when we have electric appliances and a car). That's not "a lot more".

> Sharing power is a much better idea than trying to store it in batteries, unless those batteries are in a car

Huh? Why would sharing power be a better idea? Solar panels generate the majority of their power in ~4 hour window. Energy storage is _mandatory_.

Re: Solar Roof

#169

Post by ghaff »

rhino369 wrote: post #94
ctdonath wrote: post #42

People keep overlooking the objective value of not relying on "grid" power sources. Power goes off, your system keeps going. Gasoline supply stops (I've seen that a few times), you can just power your car at home. Your system fails, grid is likely still up to cover. Supply-and-demand takes a sharp turn when supply is actually limited and can/does run out . At that point, having pre-paid for your own uninterrupted off…

I think people overvalue the value of being off the grid. The average person isn't doing anything that critical at home, so they can just deal with it. Diesel generators work for people with critical use cases. Katrina is the only time in my lifetime where a major city / region was without power and without gas deliveries for a long time.

Where I live (Northeast), pretty much the only time where an extended power outage is a serious problem is in the winter. And that's because of losing heat. A Powerwall-like "UPS" that could handle some critical systems (basically my furnace) automatically is interesting. But any solar panels are likely to be under snow and ice.

Pretty much the only thing that's really a problem for me in a power outage is losing heat because the furnace loses power and therefore potentially having pipes freeze.

Re: Solar Roof

#170

Post by sbov »

vkou wrote: post #142
bluehawk wrote: post #130

Earlier quoted context omitted.

Since we are discussing Tesla solar roofs, they suggest your installation comes with a PowerWall, thereby storing power during the day to use at night. I personally don't think we are there yet, but I think the goal is that you don't need the entire national power grid just for night electricity, just a big battery.

Batteries + roof PV, is far more expensive on a per-watt basis, then a power grid + utility-scale generation. "Just buy a $15,000 PowerWall, which you will need to replace every 10 years" is, compared to grid electricity, incredibly wasteful. There's a reason why customers and users overwhelmingly prefer centralization, even if its harmful for them in the long-term. It's cheaper, and people would prefer it to be some…

Have you done the math? If net metering didn't exist, my back-of-the-envelope calculations say it would probably break even in California. With net metering, sure, it's pointless.
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