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Really dumb Q about solar

Discussion in 'Tesla Energy' started by Sir Guacamolaf, Sep 27, 2016.

  1. Sir Guacamolaf

    Sir Guacamolaf The good kind of fat

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    Okay - thinking about adding solar to my house.
    So please pardon my n00b questions.

    1. When solarcity etc. gives you a price quote - is that solar cells only, or solar + battery?
    2. Do you usually add battery? What percentage cost does that add, what kind of battery do you get?
    3. My electricity rate is $0.12/kwh - not bad huh? Would you say solar makes sense (financially).

    TIA!
     
  2. martinicus

    martinicus Member

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    1) Typically a grid tied system doesn't have a battery, and takes advantage of a net metering policy with your utility so that you get credit for every kWH you export to the grid. In this situation batteries don't make any economic sense, unless possibly you have a time of use rate plan with very expensive peak rates, and can shift load away from peak rates. BTW solar city purchase quotes are high as they are geared towards leasing. Get purchase quotes from local installers.
    2) Typically no, as explained above. Another scenerio where you could use batteries is for emergency backup power, however this would be more expensive than a generator. A powerwall setup with several batteries is not cheap.
    3) Impossible to say, dependens on your usage and state and federal incentives. Get some quotes and calculate the time it will take you to break even based on your annual electric spending.
     
  3. Sir Guacamolaf

    Sir Guacamolaf The good kind of fat

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    Awesome, thanks!
     
  4. ecarfan

    ecarfan Well-Known Member

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    Agreed.
    Yes, even one Powerwall is more costly than a small backup generator. However, a backup generator also needs periodic maintenance and you need to keep fuel on hand for it. In contrast, a Powerwall needs no maintenance and is always ready for use within seconds of a grid failure. Plus, it emits no pollution.

    If you make a decision on whether or not to use a battery like a Powerwall purely based on the economics of it, then the Powerwall may not appear to be an attractive option. I believe there are other factors to take into account. A Powerwall enhances a solar system by further reducing one's draw from the grid, thereby further reducing one's emissions.
     
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  5. Sir Guacamolaf

    Sir Guacamolaf The good kind of fat

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    Yeah, but no battery = solar is useful only for less than 1/2 a day, and it doesn't serve as a backup system.
    My peak vs non peak rates are almost identical.
    Net metering - my state's utility company doesn't pay anything if you pump power back into their system.
    I really want solar, but the numbers aren't really agreeing with me. :-(

    Lets hope that battery + solar roof thing Elon is about to talk about is really awesome and not super pricey.
     
  6. TheTalkingMule

    TheTalkingMule Active Member

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    It all depends on where you live and the net metering rules there. But no, SCTY doesn't install a battery by default......yet!
     
  7. nwdiver

    nwdiver Active Member

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    Who's your utility? If you have an old electromechanical meter you could always risk it and fly under the radar ;) I did that for a few years in Texas until they installed a Digital meter that got madd when power flowed backward. The old meters will spin backward...
     
  8. NOLA_Mike

    NOLA_Mike Active Member

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    More than madd - my last couple of digital meters (that weren't Net Meters) would display which direction power was flowing but would count kWh UP regardless of which direction they were flowing. IOW, I could send them 45 kWh during the day and they would charge me for 45 kWh. :(

    Mike
     
  9. Sir Guacamolaf

    Sir Guacamolaf The good kind of fat

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    I have digital meters that they read wirelessly over FM transmission (or something like that). Plus I don't wanna go to jail.
     
  10. idoco

    idoco Member

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    I have grid tied solar with a 40 kwH battery backup. We use standard deep cycle lead acid batteries for the backup. Much more cost effective than the Powerwall. Approximately 11 cents per watt/hour storage vs 50+ cents per watt/hour storage.

    Lithium is great for mobile applications or high density applications where weight is a big concern. But I think lead acid is better for home solar backup.

    One other thing many people don't mention or realize. With standard grid tied solar if the grid goes down the solar goes down to prevent back feeding. If you want to keep the solar on when the grid goes out you need a gen-trans switch capable of telling the solar inverters, "it's ok to stay on....we'll take care of the isolation". The charge inverter we use for the backup batteries does this. But I guess you could do it without backup.
     
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  11. bonaire

    bonaire Active Member

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    #11 bonaire, Sep 28, 2016
    Last edited: Sep 28, 2016
    .12/kWh is great. Any time of use plan available? If not, that is a good overall rate. Sounds like Ohio or WV where natural gas and coal plants kept the price down.

    If you really "want" solar, pay for it. Economically, doesn't always make sense, but you have the 30% Federal ITC for it. That saves you 30% of the overall system cost. EVen a 8-module Solar PV grid-tied system "gets you solar" and you're up and running. I have in-laws who have a very expensive 8-module system which would cost today under $4,000. They paid $16,000 back in 2010. Not good. Today, you can find and install your own system yourself with companies like WholesaleSolar.com

    Also, a lot of individuals have chatted about Solar on www.solarpaneltalk.com. Whenever setting up for something new, get 3 different quotes from professionals but if you want to do it yourself, make sure you have all your ducks lined up. County permits, information from your local fire department to determine if you need to do anything special for fire safety, follow all NEC rules, etc. Going it alone works - but only if you are skilled or have local contractors who are also skilled.

    I live in a state with .15/kWh, no TOU rates. I have solar and it's at least a 10-year ROI. Also, be aware that in many cases, inverters need to be replaced in the out years, sometimes in years 12-15 or soon after. They should last longer but you never know.

    You should look into SolarEdge inverters as they seem to allow for power from the PV array even if the grid is down. But you need to wire-up "critical circuits" using a 2nd breaker panel.

    Lots to think about - but most people don't "go solar" to save money, really. Other reasons apply. Wiring up a house for backup battery, solar PV and all that and to have enough battery capacity for a long grid outage is getting cheaper - but it "ain't cheap" even with lower priced PowerWalls. This stuff sounds cheap on the brochure, but there's always the fine print. Get a quote from a couple companies - chatting online isn't going to offer you all the details you need to make a fully qualified decision.
     
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  12. Sir Guacamolaf

    Sir Guacamolaf The good kind of fat

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    I don't know. Chatting online here has taught me a lot I didn't already know :). Thanks for your inputs though. My dream was to not have a generator but instead have solar. I might still do it, if nothing just enough to charge the car.
     
  13. TheTalkingMule

    TheTalkingMule Active Member

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    You can always install the solar with an eye toward battery backup in the future. Depending on your location you should be able to get prices around $2.75-$3.15/W installed for decent hardware. Research the net metering rules in your state and I think you'll find you'll save money instantly if you're currently paying $.12/W.

    2 years down the line Elon will sell you a cool battery backup that can power you for a day if the grid goes down.
     
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  14. nwdiver

    nwdiver Active Member

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    Not really something they'd send you to jail over....

    There's always the option of an smaller off-grid system. You don't need to displace everything.
     
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  15. ecarfan

    ecarfan Well-Known Member

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    The SolarEdge 7600 inverter that is compatible with the Powerwall will do what you describe: automatically switch over when the grid goes down so that you will continue to get power to your home from either your PV panels or the Powerwall. That is the way my new solar system with Powerwall works. And I know it works because I have tested it.
     
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  16. vinnie97

    vinnie97 Member

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    Drat, that makes my 2013 Enphase microinverters look fantastically archaic. I also like the design idea that moves as much of the electronics away from the heat of the sun as possible (SolarEdge single inverter). Sure, if that failed, you would lose the entire system but access to and replacement of said inverter should be a relative breeze.
     
  17. miimura

    miimura Active Member

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    If I could buy as much electricity as I wanted at $0.12/kWh, I would not have solar. Normal PG&E residential rates are tiered and start at $0.18/kWh. Every kWh over about 600kWh/month is $0.40/kWh. That is quite some incentive to go solar.
     
  18. ecarfan

    ecarfan Well-Known Member

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    If humanity maintains the mindset that burning fossil fuels is okay as long as it's cheaper than sustainable energy, we are dooming ourselves to a future where the earth is far warmer than it is today.

    I recognize that many people cannot afford to move to sustainable energy right now. That is obvious. But those who can afford it should lead the way, and with increasing implementation the costs will drop, more people will be able to afford it, which will cause costs to drop further, and a self-reinforcing cycle will result in the gradual elimination of fossil fuel consumption with all the resulting benefits that will bring. It is the same way that Elon is driving the adoption of EVs: first the very expensive limited production car (Roadster) for the few who can afford it, then the lower priced higher volume production car (Model S), then the even lower priced mass production car (Model 3) that many middle class buyers can afford, etc. If no one bought the Roadster, Tesla would have failed. If some had bought the Roadster and then very few people bought the Model S, Tesla would have failed. But the Model S sold in far greater numbers than Tesla expected, and that gave Tesla the ability to tool up to launch the Model 3, and Model 3 reservations far exceeded Teslas projections which has put Tesla on a likely trajectory to be a long term success. (Note: I am not an original Roadster owner and could never have afforded to buy one, but I was just barely able to buy a Model S almost 4 years ago, so I did)

    I don't know your personal financial situation. I am only making the point that we need to try to move beyond the viewpoint that "I can afford solar now but I'm not going to do it because my fossil fuel electricity is cheaper". Those who can afford to do should do it even if the payback may be over a decade because their currrent electrical rates are very low.

    Take the long view.
     
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