Author Topic: EEVblog #938 - Tesla Solar Roofs - Are They Viable?  (Read 37208 times)

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Online EEVblog

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EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« on: October 31, 2016, 02:29:55 am »
Solar Freakin' Roofs!
How viable is Tesla's Solar Roof concept?
What did Elon Musk not mention at the product launch?
How efficient are they?
Who much energy is required to manufacture them?
What about optimum angle to the sun?
https://www.tesla.com/solar
Energy required for existing roof construction: http://buildforliving.com.au/wp-content/uploads/2014/01/BR-Roof-Tiles-For-Living.pdf
International Energy Agency on Efficiency: http://www.iea.org/publications/freepublications/publication/tracking_emissions.pdf
US Government on PV Energy Payback: http://www.nrel.gov/docs/fy05osti/37322.pdf
List of solar single companies that have gone bust: https://www.greentechmedia.com/articles/read/A-Note-to-Elon-Musk-And-The-Brothers-Rive-on-The-Integrated-Solar-Roof
Dow Chemical Solar shingles goes out of business: https://www.greentechmedia.com/articles/read/dow-chemical-sheds-solar-shingle-business
Solar shingle efficiency: http://sunpowerbyinfinitysolar.com/solar-shingles-efficiency/
Sun position and angle/elevation calculator: http://www.sunearthtools.com/dp/tools/pos_sun.php

« Last Edit: October 31, 2016, 09:31:24 am by EEVblog »
 
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Offline boffin

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #1 on: October 31, 2016, 02:45:32 am »
Powerwall II ? Really?  Why wouldn't you just do it with existing technology (Lead-Acid & electronics) all of which is available off the shelf right now?  The advantages of Lithium batteries for cars make a lot less sense in houses, where the lower weight and size really don't make as much difference.

As for the roofs, if they can make non-solar version, that looks the same, but without the solar (for a lot less money) for the off-side of your house they might have something.
 

Offline riyadh144

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #2 on: October 31, 2016, 02:48:53 am »
We should wait for the datasheets, and prices to judge.
 

Offline optoisolated

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #3 on: October 31, 2016, 02:56:42 am »
Aesthetically very much up to Tesla's usual standards. Gorgeous! At the end of the day though, if the cost of production plus the efficiency of the panels means they are still significantly below standard modular panels, I don't see this being more than a fad. :horse:

The case for the Powerwall though; no-brainer if you can afford the initial outlay.
 

Online EEVblog

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #4 on: October 31, 2016, 03:10:55 am »
As for the roofs, if they can make non-solar version, that looks the same, but without the solar (for a lot less money) for the off-side of your house they might have something.

I mentioned this in the video.
 

Offline nuclearcat

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #5 on: October 31, 2016, 03:12:44 am »
Powerwall II ? Really?  Why wouldn't you just do it with existing technology (Lead-Acid & electronics) all of which is available off the shelf right now?  The advantages of Lithium batteries for cars make a lot less sense in houses, where the lower weight and size really don't make as much difference.

As for the roofs, if they can make non-solar version, that looks the same, but without the solar (for a lot less money) for the off-side of your house they might have something.
One of benefits of lithium is that it might charge much faster. It might be beneficial for winter, if you are getting just few hours of sun, because on topping stage lead-acid charging is really slow, and if you have only 4 hours of sun, it is basically not enough to refill your batteries to full. So you might keep cycling between let's say 40-70% depth of discharge, which is not good at all for batteries health.
Sure if i understand lead-acid charging process correct and my info might be outdated.
 

Offline boffin

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #6 on: October 31, 2016, 03:21:18 am »
As for the roofs, if they can make non-solar version, that looks the same, but without the solar (for a lot less money) for the off-side of your house they might have something.

I mentioned this in the video.

OK, I admit I hadn't got that far into the video when I wrote this. But you're definitely on point, might make sense for one part of your roof (half of mine for instance that faces SW), but not for other parts, and putting something to optimally use it makes sense.  I really don't understand why sunny climates don't have ordinances requiring solar panels on roofs, plenty of places in Aus or the SW United States are perfect for solar, yet I don't see that many panels when I visit the states.

One application I did see and thought "Wow, that makes sense" is a company called Rio Grande (interestingly owned by Berkshire Hathaway aka Warren Buffet), in New Mexico USA, who used solar panels as car port roofing, and power their warehouse from it.
https://www.riogrande.com/ad/responsibility

 
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Offline Someone

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #7 on: October 31, 2016, 03:26:38 am »
The orientation east/west away from ideal doesnt reduce the power generation as much as you might think.

Through the seasons a flat panel (extreme vertical alignment) is not as bad as you make out.

You could tile your wall in Melbourne Australia with a fully vertical alignment and get 60% of the optimal 30 something degree alignment, a flat install is over 80% of the annualised generation compared to the ideal fixed orientation.

So,
assuming you aren't shaded
Less than ideal insulation angles would lose less than 50% overall, which will still payoff in many installations. The loss of generation factor from misalignment needs annualised numbers to back it up, not just single examples at one time of the year/day. Shadowing will be the killer not alignments and you can put cheaper but matching tiles on the sides facing away from the sun.
 

Offline nuclearcat

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #8 on: October 31, 2016, 03:43:34 am »
Few questions of such roof might be interesting:
1)Electrical hazard safety. While they claim their tiles are really strong, they don't go pieces, but they might still break. Adding that it is mentioned this shingles mostly are connected in series, if it will have similar micrometeorite impact as Dave has, it is possible that this shingle will be open circuit, and this part of roof, especially if it is wet will be under high voltage. And if such thing wont be noticed, stepping on such wet roof might be quite dangerous. Also, seeing how connector is done, and how many of them will be on roof, there is some risk of bad insulation/bad connection, which leads to same issue, especially it might happen after few years of operation, and due design it is really hard to check that connections. I am not talking that stepping on such shingles may cause disconnection and open circuit as well.
As i read before, firefighters might not use some part of their strategy during extinguishing fire, because solar installations might be serious risk factor for them. With solar shingles it might get much worse.
2)Solar cell efficiency drops when they heated, while regular solar panels design help them to cool down by free cooling, regular shingles according statistics can get up to 70C, and on this temperature efficiency drops quite significantly (30-40%? not able to get precise numbers).
 
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Offline GeekGirl

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #9 on: October 31, 2016, 04:15:29 am »
Hi all,

My $0.02 (Inc GST) ;)

 #1 People are saying no to whole roof as it will have a very low efficiency as an entire system. BUT I think we are looking at the problem the wrong way, these solar roof times are designed for when you build a new house / modify a house etc ie when you do the roof from scratch. So why not say we want 100% coverage. We want a good efficiency, So we will design the new roof to accommodate this ie like the old warehouse roofs where  they were a saw tooth pattern. Then we can have BANKS of panels all pointing at the optimum angle at the best orientation we can achieve (the roof would still need to be square to the building or the builder would go nuts trying to construct it ;).

 #2 I think that it would be cheaper and easier to install if the "Tile" was a bigger size, as this would lessen the amounts of interconnects. If you use the idea above then you do not need to cut "tiles" as you can start from the centre of each row and have an overhang each side to take up the remaining width of the "tile"

 #3 As nuclearcat has mentioned interconnection is a major problem if the tiles are connected in a vertical column with the pins you can see at the top of the tile in the video, As the roof expands and contracts if will twist which will make connections go open circuit (even if they have a spring that is 100% of the thickness of the tile). This is not so much of a problem in the US and Europe where they tend to put sheets of plywood down before the tiles but here in Au where we have battens straight on the roofing timbers the roofs do move. They will also (as pointed out by nuclearcat) move and go open circuit as weight changes on the roof ie a human walking on the roof. This will lead to arcing (as this is DC after all) which over time will damage the contact..... Suddenly your roof is on fire. Also how are these tiles going to stand up to other trades opening up the roof ? (eg plumbers, electricians, security techs .....) Generally they just work out where they want to go in or above a cavity and kick a few tiles up ? What ever the interconnect system it needs to be able to withstand the abuse a roof gets !

 #4 I know fire fighters do not like anything that is live while they are trying to put out a fire. If they can safely reach the fusebox (at least around here) they will throw all the breakers and pull the supply authority fuses that way they know the only thing live is the overhead / undergound cable to the house and then to the fusebox. There have been designs I have seen for roof top solar isolators that are remote controlled and fail safe (if the house looses incoming power the inverter shouts down and the device opens the solar DC bus in both legs up on the roof before any cables go into the roof cavity)

Regards,

Kat. :)

" I am an Engineer, Not an English teacher, God Damn it" Moi 1999

Regards,
Kat. :)
" I am an Engineer, Not an English teacher, God Damn it" Moi 1999
 

Offline station240

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #10 on: October 31, 2016, 04:26:05 am »
My understanding is Tesla/Solar City's solar roof is designed to solved a particular problem with US houses.
That is where the home owner wants solar, but needs a new roof to mount it on.

It's no accident the four roof tile types are those most difficult to mount normal solar panels to:
a) Ashfelt sheeting roof mounted over plywood.... yeah lol
b) Slate roof
c) Tuscan tile roof
d) Modern flat tile roof (actually not that difficult)

I'm just not seeing this product selling well outside the US. Does Solar City even have a presence in Australia ?
 

Online blueskull

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #11 on: October 31, 2016, 04:38:50 am »
Error: CO2 level not found ;D.
 

Online blueskull

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #12 on: October 31, 2016, 04:50:39 am »
I have a stupid question, how much electricity can that thing generate? How much generated energy is used for HVAC?
In northern China we have a system using solar energy to heat water to replace water heater, or even water radiator heating system for an entire house. That's a LOT of free energy just from 200 years old technology -- just an array of concentric vacuum quartz tube painted in black, with the interior holding water to be heated up.
A $200 solar water heater occupying 1 square meter can produce enough hot water for shower and dish washing for a typical Chinese household and consumes no electricity at all. That would be half electricity consumed in the winter.

So, why Americans do not invent a solar AC system, then when combined with solar heater, the entire system takes care of all HVAC demands while only consuming a little electricity for fans. That would be very efficient and does not need energy storage since the room itself stores thermal energy with no additional cost.
 

Offline ziggyfish

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #13 on: October 31, 2016, 04:50:53 am »
When will the Left realise that there is no such thing as a one size fits all solution.

Solar sounds great in theory, but in practice, it simply won't work on a large scale. This and Solar Freaking Roadways is the perfect example of this.

Even those who say their state or country 100% relies on renewable energy are often using non-renewable energy to supplement it.

Take South Australia. A fair bit of its energy comes from Victoria (it's the reason why South Australia had a statewide power outage this year), and soon to be NSW. However, the government argues that the state runs on 100% renewable energy.

This same thing can be said for Germany and many other countries that claim to be 100%.

-----

We simply don't have the technology to make solar or wind a sustainable, efficient and scalable energy source.


 

Offline boffin

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #14 on: October 31, 2016, 04:59:39 am »


So, why Americans do not invent a solar AC system, then when combined with solar heater, the entire system takes care of all HVAC demands while only consuming a little electricity for fans. That would be very efficient and does not need energy storage since the room itself stores thermal energy with no additional cost.

It's a good question, my parents had solar hot water on their house 25 years ago, and it's not like we have the most ideal weather for solar here in Canada.  It was just a pre-heat tank for water going into the hot-water tank.
 

Offline radar_macgyver

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #15 on: October 31, 2016, 05:15:01 am »
In northern China we have a system using solar energy to heat water to replace water heater, or even water radiator heating system for an entire house. That's a LOT of free energy just from 200 years old technology -- just an array of concentric vacuum quartz tube painted in black, with the interior holding water to be heated up.

That's a thermosyphon system, which works well as long as the outdoor air temperature doesn't fall below freezing (tubes would burst otherwise). In freezing climates, one can use a dual-loop system that circulates water+antifreeze into a collector, and runs this through a heat exchanger to heat up water. Lots of info here: http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm
 

Online blueskull

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #16 on: October 31, 2016, 05:28:01 am »
That's a thermosyphon system, which works well as long as the outdoor air temperature doesn't fall below freezing (tubes would burst otherwise). In freezing climates, one can use a dual-loop system that circulates water+antifreeze into a collector, and runs this through a heat exchanger to heat up water. Lots of info here: http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm

I was referring to an ICS system, not thermal siphon system.
 

Offline ziggyfish

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #17 on: October 31, 2016, 05:31:53 am »
When will the Left realise that there is no such thing as a one size fits all solution.

Solar sounds great in theory, but in practice, it simply won't work on a large scale. This and Solar Freaking Roadways is the perfect example of this.

Even those who say their state or country 100% relies on renewable energy are often using non-renewable energy to supplement it.

Take South Australia. A fair bit of its energy comes from Victoria (it's the reason why South Australia had a statewide power outage this year), and soon to be NSW. However, the government argues that the state runs on 100% renewable energy.

This same thing can be said for Germany and many other countries that claim to be 100%.

-----

We simply don't have the technology to make solar or wind a sustainable, efficient and scalable energy source.
This South Australia Gov. website claims more modest renewable energy supply levels. http://www.renewablessa.sa.gov.au/
Just where does Germany claim 100% renewable? What other countries do likewise?  Germany as far as I am aware also uses coal power so it must be difficult to claim 100% renewable.
What does "We simply don't have the technology to make solar or wind a sustainable, efficient and scalable energy source." actually mean? Are you claiming it is impossible to develop the renewable technology? Or that wind/solar cannot provide energy on a windless night? Or something else? Is it even necessary for wind/solar to provide baseload power?

What I am saying is that we don't have the advances in technology to make solar sustainable. Whether we will be able is yet to be known.

Anyway hers the German reference.
http://reneweconomy.com.au/germany-nearly-reached-100-percent-renewable-power-on-sunday-32091/
 

Offline nuclearcat

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #18 on: October 31, 2016, 05:36:18 am »
Electrical supply has multiple challenges.
1)Most of renewable energy are not stable in term of electricity generation. Exception - hydropower, it is plainly perfect. Solar has issues at cloudy weather, winter, night. Wind - depends.
(Battery storage of energy economics/longevity/environmental impact are terrible, molten salt for solar/hydro storage is much more promising)
2)Some supplies has drawbacks, for example some nuclear power cannot change output enough fast for fluctuating power consumption during the day. (not load following) Some are load following, but cannot compensate enough fast events such as "TV pickup".
This means you need some very quick "maneuvering" capacity, and if you don't have hydropower, this means thermal plants (gas/coal), just to supply enough energy to provide sufficient power.
It is serious problem, and very interesting indeed, i suggest read about TV pickup in wikipedia.
Supplying energy from other areas has it's costs as well, because of transmission efficiency, line cost, fault tolerance questions and etc.
So i believe it will be bad choice for current moment to be 100% renewable in countries who doesn't have enough hydropower, without having alternative ways to store energy. So only they can brag, when they have enough output at day from solar, that "waw, at current minute we are 100% renewable", but at evening, while demand much higher and there is no solar, they are burning coal like hell.
I believe proper smart grid will help a lot optimizing consumption at low supply periods.
 

Offline mikeselectricstuff

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #19 on: October 31, 2016, 05:37:45 am »
Video is showing as private
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
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Offline jonovid

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #20 on: October 31, 2016, 05:47:46 am »
Quote
Just where does Germany claim 100% renewable? What other countries do likewise?  Germany as far as I am aware also uses coal power so it must be difficult to claim 100% renewable.
  :-DD like diesel vehicle emission claims. its all relative. even al gore has his own central air conditioning , but tells others not to have them.   http://oilprice.com/Energy/Energy-General/Al-Gores-Hipocrisy-The-Climate-Crusader-Profits-from-Fossil-Fuels.html

the video is gonski :-//
Quote
Solar Freakin' Roofs!
How viable is Tesla's Solar Roof concept?
What did Elon Musk not mention at the product launch?
How efficient are they?
Who much energy is required to manufacture them?
no one asks about fuel consumption if you own a Rolls Royce. its just about the most expensive things money can buy.  8)
however I find no fault in the idea  even with no change in the weather whatsoever, whether you have this or not IMO . viability rests in the sales of the product. 
EV Rolls   http://www.caradvice.com.au/42211/rolls-royce-phantom-ev-in-the-pipeline/
« Last Edit: October 31, 2016, 11:17:44 am by jonovid »
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Online blueskull

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #21 on: October 31, 2016, 05:48:06 am »
Video is showing as private

Tesla's lawyers must be working hard and quick.
« Last Edit: October 31, 2016, 06:02:07 am by blueskull »
 

Offline nuclearcat

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #22 on: October 31, 2016, 05:50:02 am »
I dont want start conspiracy theories, but always they come up in mind.
But let's hope they called Dave and offered him completely free installation for test, including Tesla car, in exchange for detailed review :)
 
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Offline jonovid

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #23 on: October 31, 2016, 05:57:18 am »
new video
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Offline mikeselectricstuff

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Re: EEVblog #938 - Tesla Solar Roofs - Are They Viable?
« Reply #24 on: October 31, 2016, 05:57:34 am »
It's back - maybe just a YT glitch
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