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Solar panels, a realistic solution to charging?

Discussion in 'North America' started by SCW-Greg, Jul 8, 2012.

  1. Lloyd

    Lloyd Active Member

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    I preveiously posted our PG&E rates, and we have Time of Use meters which changes the rates schedules by time and season. CA has mandated some of these buybacks of the solar power which has created higher rates , but also allowed those that install the solar/wind power to reap the benefits. I would be happy to provide you with any other documentation you need. I understand that CA is being looked at as a model for the rest of the country, especially TOU meters.
     
  2. doug

    doug Administrator / Head Moderator

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    Is that $0.48/kWh what you would pay for usage during the day if you didn't have solar?
     
  3. Lloyd

    Lloyd Active Member

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    That is a peak summer rate regardless of if you have solar or not. When the meter moves backwards during that rate time, that is the rate that you get for your solar production, and the rate that you pay if you use more than you produce.
     
  4. SCW-Greg

    SCW-Greg Active Member

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    So I have two bids back from Solar City and Mr. Sun Solar. If I want to be net neutral from my electricity usage, I need about 8.7 to 9kW system, and my roof would support that, and I have about as goods you can have South face exposure. No trees, mountain top, often above the fog, etc.

    However both bids (if I want to buy and own, not lease) came back at $40 and $42k, netting after rebates and incentives, down to $20 and $22k. This puts my payback period at around 17 years.

    I think I need three more bids.

    The other issue I have before I can move forward, is an aging shake roof. I probably have 3 to 4 years left on it. I'll need to replace the roof first.
     
  5. wycolo

    wycolo Active Member

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    Ok, so CA doesn't cut you down to 'avoided cost' rate like WY does. Getting only two to three cents per KWH that we in WY pump back into grid is NO incentive at all, but just being grid connected is a plus nonetheless due to the intrisic benefits of being connected. Also I suspect my power coop knows more about what is going on by use of their new remote-reading meters. Need to do more research since at this point I don't know squat about home solar systems, except having one here seems to be indicated for charging one or two BEVs. Maybe just an off-grid system without batts would be a simple solution.
    --


    “I’d put my money on the sun and solar energy. What a
    source of power! I hope we don’t have to wait until oil and
    coal run out before we tackle that.”
    —Thomas Edison
     
  6. sublimaze1

    sublimaze1 8Dec2012 / Leeroy Jenkins

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    California pays $.48 per kWh ???
     
  7. rcc

    rcc Model S 85KW, VIN #2236

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    San Jose, CA
    CA has two basic rate structures: Time of Use and Tiered. Tiered doesn't care about when you use power but cares how much. The more you use per month, the higher the rates.

    For PG&E (SF Bay Area primary provider), the current rates for standard Tiered Residential (E1) start at about 13 cents per kWh and go up from there. Once your usage hits 1.31x the "baseline" allotment, you're paying about 28 cents per kWh. That goes up to about 33 cents per kWh once you hit 2x the baseline allotment. PG&E adjusts the precise rates all the time. They've had 3 rate schedules for 2012 and the year's not over yet.

    Peak rates for Time-of-Use (E9A) are 30 cents per kWh during summer and 9 cents during winter. Rates drop to about 4 and 5 cents during off-peak for summer/winter.

    The upshot for the SF Bay Area is that you win if buy enough solar that PG&E is crediting you for power but you still owe PG&E some money. The win goes down if you don't buy enough solar or you buy so much so that PG&E pays you. Because when they pay you, they pay wholesale supplier rates, not retail rates and the wholesale rate isn't enough to cover the cost of generating that power from solar panels.

    Details follow:

    If you generate less power than you use, CA requires that you get credit for the generated power at retail rates. So if you're on a Time-of-Use plan and at 2 pm, power costs 30 cents per KWH, if your meter is running backwards at 2 pm, you get credited 30 cents per KWH that you generate. It's simpler if you're on the standard tiered residential plan: they just add up your usage, subtract out the power you generated and you pay standard rates for what's left over.

    In both cases, if you generate more power than you consumed over your one year true-up period, the power company (or at least PG&E) pays you wholesale rates, not retail rates for the surplus. I think that's currently about 4 cents per kWh.

    So if you want to maximize your ROI for this part of CA, you need to look at your current and projected usage patterns and then get the right amount of power and put yourself on the right rate structure. Time-of-use works really well for people who can avoid using lots of power during peak hours. They get more credit in the summer for their power produced and pay less for power consumed. If you've got kids so you're running the AC a lot during the hot months, staying with the standard rates may be a win.

    If you guess wrong and you don't buy enough solar, you'll be paying for power at peak rates or at 3x baseline prices depending on your plan. If you guess wrong and buy too much solar, PG&E will pay you money but almost certainly less money per kWh than it cost to put the panels in. Even with the best SolarCity plan, the cost of solar power is 9.9 cents per kWh for me. So if I buy too much solar, I lose 5 cents per kWh for every kWh that PG&E pays me.
     
  8. Lloyd

    Lloyd Active Member

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    #48 Lloyd, Oct 29, 2012
    Last edited: Oct 29, 2012
    File0467.jpg


    California credits you the same rate that you pay retail. If you have excess left at the end of your true up period, they pay you at .04 cents per KWh.
     
  9. Tesla 940

    Tesla 940 Member

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    You can do the roof THEN install the solar - but...

    When I had my solar installed 9+ years ago I had the same situation with the roof. I coordinated the roof with the solar. The roofer removed the old roof, prepped for the new roof, then the solar company installed the supports for the panels with the flashings, then the roofing finished, then the solar company did the final installation. It went really smooth with less than a 1 week delay.

    My 3Kwh system with TOU has resulted in only 2 years in which I owed money - both less than $20. We don't us the AC much and the Roadster is only driven 5k a year.
     
  10. mulder1231

    mulder1231 Active Member

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    #50 mulder1231, Oct 29, 2012
    Last edited: Oct 29, 2012
    Actually, I'm in the third tier just after one week of usage, so in my case I already benefit from the TOU plan, even before getting my Model S! TOU is a nobrainer for me.

    I wanted to go solar but there is this building code issue I'm dealing with in San Mateo county that dictates 3' clearance at the roof ridge and from the roof overhang. This only allows me to install a single row of panels (I can fit max 6 panels but need 12 for a 3kWh system to cover all of my driving).

    They say it's a safety issue. Firemen have to be able to walk on the roof in case of fire. (Stupid rule, they have the entire other side of the roof to walk on :mad:)
     
  11. swaltner

    swaltner Member

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    Odd, since http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=WY01R says Wyoming has Net Metering. This says it applies to electric coops and has Net Excess Generation "Credited to customer's next bill at retail rate; excess reconciled annually at seasonal avoided-cost rate". To me, that looks like you get full retail credit for your energy production. The avoided cost comes into play probably once a year where you might get cash back.

    In Kansas, I don't get any cash back, but I do get full retail credit for what I generate and dump onto the grid, which can carry over from month to month until the end of the year. I activated a 5 kW system on July 31. Since then, it's generated just over 2,000 kWh of electricity. Of that, over 1,100 kWh was excess and dumped onto the grid. Over the same several months, I later pulled about 800 kWh back off the grid. The PV system is large enough that my meter runs backwards during the day, anytime that the air conditioner is not running. I'll build up excess credit, which will expire at the end of the year, and then start building up a credit for the cooling season next summer. I'll probably pay for some electricity towards the end of the summer, but it should make me close to zero net electricity usage.

    One could possibly come up with a system that worked off-grid, but when you have the grid available, just connect the PV system to it.
     
  12. Rifleman

    Rifleman Now owns 2 Model S's!!!

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    I am a fireman, so I can shed some light on this. One of the best things that we can do on a structure fire is vertical ventilation. For this to be me most effective, we must be able to cut a hole in the roof directly above the fire. Doing this will allow the heat and smoke to escape through the room without being pushed into the rest of the house. This limits the spread of the fire, but most importantly, greatly improves smoke and heat conditions inside the house, allowing for the search team to locate victims quickly, and also giving anyone trapped inside the house a much greater chance of surviving. If we only have access to 50% of the roof, there is a 50% chance that we would not be able to cut the hole directly above the fire, rendering vertical ventilation non-effective. Hope this clear this up. Just about every rule in the fire code is written in blood, we really do not make things up just because it sounds like a good idea, but because someone got killed, and a change to the code was made to prevent it from happening again.
     
  13. dflye

    dflye S Sig Perf 414, VIN 814

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    So the 3' border may work somewhat, but seems that the code would better serve the described firefighting technique if it instead limited the square footage of each group of PV panels and required an aisle between groups of PV panels. That would provide better access to the various rooms under a larger roof that a simple border wouldn't.

    Now I got all worried and started looking at the photos I took of the PV array that was just put on our roof last week to determine if the layout "buried" any rooms... and then remembered we have a cavernous one-room attic that it is over! :biggrin:
     

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