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Powerwall 2 and Integrated Solar

powerwall.tesla.com

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Re: Powerwall 2 and Integrated Solar

#211

Post by sfblah »

gregn610 wrote: post #182

X-post from reddit as it might get an answer here... http://m.imgur.com/pgskG9q?r This LNG ship got me wondering about a battery equivalent, charged up in a desert solar farm and shipped to a major city. I get 16 Powerpacks per 40ft container 5100 containers per Panamax ship =81600 powerpacks per ship At 95kWh per pack = 7752MWh per ship ( based on powerpack v1) So is that like two Hinckley C nuclear reactors worth o…

Lithium Ion batteries lose charge over time, so during transport they would discharge.

Lithium Ion batteries can handle a relatively small number of recharge cycles (when compared with the number that a metal cylinder/sphere can handle when just filling it up with LNG)

Re: Powerwall 2 and Integrated Solar

#212

Post by vollmond »

Loic wrote: post #118

Quick question for the people living in the US (Target customers of the Powerwall). What is your yearly power usage? On the website[0] they put for sizing 10kWh/day/BR. Which means 14600kWh/year for a 4 bedroom house. Here in Germany, working from home with a 4BR+office house, we are using 2550kWh/year. So, I suppose the Tesla sizing is to support a "peak day" usage, but still, I am surprised by the calculations. Thi…

Just to add more anecdata:

* 150-year-old rowhome in central Pennsylvania, USA.

* 2 adults, 2 small children, dog/cat.

* Window unit air conditioners (2 running most of the time in summer, with a 3rd in the attic office running a lot less since I don't use it much). Hoping to install mini-split system eventually, but it's low priority

* Gas steam heat

* Gas stove/oven

* Gas water heater (I think)

* Electric baseboard heat in 2 rooms

* Electronics: tv/roku, modem/router, 2 laptops. 2 phones charged occasionally

* Lights are almost entirely CFL/LED.

My usage over the past year is just a hair under 14,000 kWh. Around 1500/mo when the A/C or baseboard heaters are on. Lowest months were April/May when both of those were off and I dipped down to 500 kWh.

If my math is right, most of the rest may be due to ceiling fans -- we have 5-6 that are left on pretty much year-round. Assuming they're each 75 watts, that's around 50 kWh/mo per fan. It never occurred to me to wonder how much power they might use.

So, if I leave A/C and baseboard heating off, and only run fans in currently-occupied rooms (bedrooms at night, living/dining/kitchen during the day), my usage would be about 4000 kWh/year.

How do you use so much less? Tiny efficient fridge? That's the only big item left in my house.

Re: Powerwall 2 and Integrated Solar

#214

Post by mmcconnell1618 »

usrusr wrote: post #178
Klez1993 wrote: post #166

Earlier quoted context omitted.

"They're also charged to full capacity or depleted to empty a lot of the time." Does it affect battery life if I keep my phone charged even if it's at 100% ? (My phone is charging during the night, so it will be at 100% for a long time and keep charging). If it reaches 0%, how does that impact battery life compared to reaching 20% and charging up ? I never looked up these things but it might influence how I charge al…

Modern batteries deteriorate from heat and from the time they spend at the extremes of their charge cycle. As a general rule of thumb, you would get the lowest amount of wear by keeping the battery as close to 50% as possible all the time, only charging higher than that right before use and just enough to make it comfortably to the next charging opportunity. One of the worst things to do to a battery (not as bad as a…

Sounds like an opportunity to have scheduled charging. I'd like to plug my phone in at night and have the phone keep itself at some minimum until an hour before my morning alarm. Then start charging so it reaches 100% just about the time I wake up and unplug. Maximizing battery life might conflict with phone manufacturer's goal of getting you to buy a new phone every few years.

Re: Powerwall 2 and Integrated Solar

#215

Post by sfblah »

samcheng wrote: post #103
Fej wrote: post #102

How long are the batteries going to last? With phones, we expect the battery to deteriorate after a couple of years. This is an investment. Will it need to be replaced in a few years' time?

Tesla automotive batteries have shown pretty strong resilience over the few years they have been running, even on cars that have been driven hard. Cars are at >90% capacity after 50,000 miles. It's not like the batteries need to be replaced frequently. http://i.imgur.com/nWM9ZrS.gif I wonder if these Powerwalls will have the same sophisticated battery thermal management system as the cars?

Houses and roofs last far, far longer than cars. 50k miles is 4 years for many drivers.

Re: Powerwall 2 and Integrated Solar

#216

Post by sfblah »

doikor wrote: post #125
Uptrenda wrote: post #119

You can buy 12v 250ah deep cycle AGM batteries from China for around $5 per battery -- lets assume another $15 for world-wide shipping. These kind of batteries would have around 3kwh of storage per battery but since you shouldn't discharge them to more than 50% lets also say that you need to double the number of batteries to achieve 14kwh of usable power for 28kwh of total capacity. At that capacity level, you would…

And once your self made cheap chinese battery pack ends up catching fire and taking your whole house with them you understand why you want to pay for some actual company to do this and have some quality control/insurance.

Yeah because Lithium Ion batteries never catch fire.

Re: Powerwall 2 and Integrated Solar

#217

Post by will_hughes »

andreyk wrote: post #116

His argument about the solar roof starts by equating the situation to how Tesla started out - electric cars were slow and ugly and needed to be sexy and cool to be attractive, and the same is true for solar. Except I highly doubt this is true here - do people really mind the look of typical roof-mount solar? My impression is that the upfront cost is just too high and cost recoup is just too slow. The argument for the…

> do people really mind the look of typical roof-mount solar

Depends on the people you're asking.

Some Home-Owners-Associations in the US forbid the installation of rooftop solar on visual grounds. Though some states have signed laws stopping HOAs from doing this.

Re: Powerwall 2 and Integrated Solar

#218

Post by onesun »

anexprogrammer wrote: post #65
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.

That's not really how it looks in the pictures on their site. It looks more like they are butted together with no overlap. Also, I'd think you'd want just as much overlap on the long side for weatherproofing. This does raise an interesting question; how are they weatherproofing this installation?

Re: Powerwall 2 and Integrated Solar

#219

Post by Keyframe »

j1vms wrote: post #165
jacquesm wrote: post #156

Earlier quoted context omitted.

The big difference is because of air conditioning and baseboard heating, two things that are relatively rare in Europe.

> The big difference is because of air conditioning and baseboard heating (...) Which makes you wonder why there is not as much high-profile attention on A/C (and to a lesser extent electrical heating) as being a problem worthy of rethinking by Silicon Valley (perhaps even ahead of solar, in North America).

It might be (it is) anecdotal, but as someone from Europe it struck me odd how much Americans love their A/C. Too much, in fact. Almost everywhere I went it was too cold. Somewhat like in SE Asia. That might be the answer to high energy use.

Re: Powerwall 2 and Integrated Solar

#220

Post by mrfusion »

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.

If you use a laptop a ups can power your router and modem for quite a long time.

Or you can buy a huge ups for a lot less than 3000 and power a desktop machine too.

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