Powerwall 2 and Integrated Solar • Hacker News Board

Re: Powerwall 2 and Integrated Solar

#61

Post by JBReefer » Sat, Oct 29, 2016, 3:30 AM UTC

andrewtbham wrote: post #13

the cool thing is that they look good... they look like a normal roof at the angle you would see from the street in front of the house, but from above... from the angle of the sun they are transparent and you can see the solar cells. I know some rich people that want solar but their neighborhood associations won't allow it, but I don't think they would not have an objection to these roofs. they look really nice.... I…

This product strategy certainly seems easy to copy, I agree. That's good for humanity and bad for Elon financially (I think that's the point for him, I don't think he cares about money outside of more commas).

Re: Powerwall 2 and Integrated Solar

#62

Post by TheSpiceIsLife » Sat, Oct 29, 2016, 3:30 AM UTC

onesun wrote: post #56

Any idea why the solar cells aren't packed more densely? It looks like there's a lot of wasted space on due to a square cell centered on a rectangular tile.

From when I was reading more about solar cells I recall there being something about the distance from the conductor (the two stripes visible equidistant from the midline of the cell) being a problem especially with monocrystalline cells, which these appear to be. I think this was more a problem for cells that had the conductor fixed to the back of the cell.

Google image search for monocrystalline solar cell and you'll see they are all square. I had a brief go at searching for anything to back up my claim but lost interest.

I might simply be that the silicon ingot they are cut from is cast round, see this[1] picture and it's less wasteful to cut a square with chamfered corners than to cut a rectangle, which would necessitate an ingot with an elliptical cross section, which would probably be harder to cast due to uneven cooling, maybe.

1. http://www.tindosolar.com.au/learn-more/poly-vs-mono-crystal...

Re: Powerwall 2 and Integrated Solar

#63

Post by taysix » Sat, Oct 29, 2016, 3:31 AM UTC

mrfusion wrote: post #47

ChuckMcM wrote: post #40

Earlier quoted context omitted.

That was my question as well, this from the Techcrunch article: "The current versions of the tiles actually have a two percent loss on efficiency, so 98 percent of what you’d normally get from a traditional solar panel, according to Elon Musk. But the company is working with 3M on improved coatings that have the potential to possibly go above normal efficiency, since it could trap the light within, leading to it boun…

Normal shingles have a lot of overlap right. Wouldn't most of that moat be the overlap?

You're right. In the second tile he shows it look like 60-70% is just the moat.

Re: Powerwall 2 and Integrated Solar

#64

Post by gregpilling » Sat, Oct 29, 2016, 3:31 AM UTC

toomuchtodo wrote: post #21

option wrote: post #18

Earlier quoted context omitted.

In CA, it is illegal for HOA to block solar installations

Also in Florida, surprisingly.

And Arizona.

Re: Powerwall 2 and Integrated Solar

#65

Post by anexprogrammer » Sat, Oct 29, 2016, 3:32 AM UTC

onesun wrote: post #56

Any idea why the solar cells aren't packed more densely? It looks like there's a lot of wasted space on due to a square cell centered on a rectangular tile.

A little over 50% of a roof tile is covered by other tiles to provide the weatherproofing. The square solar part covers nearly all the exposed area.

Re: Powerwall 2 and Integrated Solar

#66

Post by JoeAltmaier » Sat, Oct 29, 2016, 3:32 AM UTC

TheSpiceIsLife wrote: post #58

intrasight wrote: post #49

For $3000 this would be easy to justify just to keep my computer and network operating. I work at home and our power goes out too frequently. Is usually just for 10-20 seconds and my UPS takes care of that. But sometimes it is out for several hours - I'll say several times per year. If I can't work, I can't bill.

Where are you seeing $3000? When I set it to 1 Powerwall it tells me: One 14 kWh Powerwall battery $5,500 Installation and supporting hardware starts at $1,000 Total estimate $6,500 Requires $500 deposit for each Powerwall

Hm for that price I can install a natural-gas generator. Have power for days if necessary, full power on all circuits.

Re: Powerwall 2 and Integrated Solar

#67

Post by kbaker » Sat, Oct 29, 2016, 3:33 AM UTC

dghughes wrote: post #52

As much as I like the idea after reading about the Note 7 and then a battery fire at DARPA I'm not fond of a giant battery lithium-ion battery in my house.

Lithium-Ion technology is pretty well-understood at this point.

Just remember that there are 10s or 100s of Billions of Li-Ion batteries around the world, and having a single one fail catastrophically is still enough to make headlines...

Re: Powerwall 2 and Integrated Solar

#68

Post by AndrewKemendo » Sat, Oct 29, 2016, 3:38 AM UTC

I signed up for the original powerwall and as it turns out it's not Tesla - it's solarcity (I get it, they are the same now). Oh and by the way you have to have the solarcity solar panels installed and running for the powerwall to be installed, which has a cost of it's own.

My guess is that this isn't any different given this text:

Powerwall 2 is a battery for homes and small businesses that stores the sun’s energy and delivers clean, reliable electricity when the sun isn’t shining.

Re: Powerwall 2 and Integrated Solar

#69

Post by JoeAltmaier » Sat, Oct 29, 2016, 3:38 AM UTC

toomuchtodo wrote: post #60

foobarqux wrote: post #45

I thought Straubel said that the Powerwall was meant not for offpeak storage but for emergency backup.

That Powerwall was of a different chemistry, and has been discontinued. EDIT: This is a baller feature: "Always Connected: Monitor your solar energy use in real-time and receive alerts when Powerwall is preparing for cloudy or severe weather. " They're performing weather forecasting, and then ensuring the Powerwall has charged up for a possible outage event. Brilliant.

I cannot imagine what preparation they could be making. Surely the default process is to charge the powerwall at all times if feasible. What extra operation could it do in the event of a bad weather forecast? Other than tell you about it.

Re: Powerwall 2 and Integrated Solar

#70

Post by TheSpiceIsLife » Sat, Oct 29, 2016, 3:42 AM UTC

JoeAltmaier wrote: post #66

TheSpiceIsLife wrote: post #58

Earlier quoted context omitted.

Where are you seeing $3000? When I set it to 1 Powerwall it tells me: One 14 kWh Powerwall battery $5,500 Installation and supporting hardware starts at $1,000 Total estimate $6,500 Requires $500 deposit for each Powerwall

Hm for that price I can install a natural-gas generator. Have power for days if necessary, full power on all circuits.

Which still ties you to the 'grid' insofar as you need the natgas supply chain, even if you have a huge reservoir you'll eventually run out. Having said that, batteries and solar panels don't have an unlimited life span either.

I'm looking at buying a petrol powered generator for reasons other than home power generation, but it will be reassuring to know we have backup power at home, but I don't think I'm allowed to store any more than 25L in one container on my suburban property. I guess that would be 25L plus each of our two cars with full tanks.

It would be fairly trivial to convert a petrol powered generator to run on propane from the barbecue gas cylinder, I've had experience installing gas kits on carburettor engines in cars.