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Two Word case for staying on-grid w/solar..... Wind Power

Discussion in 'Energy, Environment, and Policy' started by nwdiver, Mar 2, 2015.

  1. nwdiver

    nwdiver Active Member

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    With all the talk about going 'off-grid' when batteries are cheap enough I think it's important to keep perspective of the advantages of the grid. Aside from the obvious facts that some people simply don't have enough room for a sufficient amount of solar, solar insolation change A LOT depending on weather and time of year, it's better to export excess than idle your panels when the batteries are full ect, ect....

    Wind is currently the cheapest renewable source we have on a per kWh basis. While I fully expect solar to eclipse wind (no pun intended) in the next ~5 years in terms of cost... it will likely ALWAYS be cheaper to generate energy with wind than to store solar. Wind and Solar are near perfect companions. Wind generates more power in the winter, solar more in the summer. Wind is most active in the early morning hours before the sun rises... when solar is generating nothing. The disadvantage of wind is that unlike solar it's not cost effective small scale. You need 1MW+ wind turbines and you generally can't install those in your backyard... fortunately for us, we have transmission lines.

    One of the core principles where I work is 'Elegant Efficiency'... basically getting the most bang for your buck. If there is demand for power... it's more efficient to export it so it can be used than store it in a battery. If there is a clean supply of energy it is better to use it than draw it from a battery. One day we will have to choose between curtailing our panels or storing their production in a battery... Until that day comes self-consumption and export are significantly more efficient. Solar during the day, wind at night... from the perspective of 'elegant efficiency' storage should be a last resort.
     
  2. JohnSnowNW

    JohnSnowNW Active Member

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    Aside from people who move up into the mountains...I wasn't aware that going "off-grid" meant detaching yourself from the grid. I took it to mean removing your reliance from the grid.

    I agree, it would make little sense to waste energy simply because you cannot use it.
     
  3. Robert.Boston

    Robert.Boston Model S VIN P01536

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    At the risk of putting words into @nwdiver's mouth, there are some who want to install large battery systems so that they can generate all, or nearly all, their own power. There are many motivations for such an installation. @nwdiver makes the case that, on pure economics, this approach isn't as cost-effective as buying wind power at night. Some storage might still be wise to flatten out your demand during the day, to avoid costly demand charges.

    Thinking about this from a system perspective, @nwdiver makes a compelling case. If you aggregate the output from diverse renewable energy sources, particularly those that have different generation profiles like wind and solar, what you are left with is a much smaller net demand compared to using one source alone. That net demand could be met with fossil power or storage. Taking this down to the level of the consumer, however, they only have one cost-effective renewable energy option: solar. Other options, such as wind, hydro, marine, geothermal and biomass, are only cost-effective at grid-scale. So in an optimum system, consumers will sell solar and buy wind/hydro/marine energy, and use local storage only around the edges.
     
  4. brianman

    brianman Burrito Founder

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    As John hints, perhaps we need some terminology refinement. I've heard people use "off-grid" in the way nwdiver hints, in the way John hints, and in other ways like the "no sign you were ever here" (think "the Net" movie).

    Some terminology to concern:
    - grid-dependent
    - grid-connected
    - grid-tied
    - grid-net-consumer
    - grid-net-producer
    - grid-only-during-dry-windless-eclipses
     
  5. strider

    strider Active Member

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    My struggle is that going off-grid (which has one and only one meaning - not having a connection to the grid, period) and having a stable full of EV's is almost an oxymoron. Solar generates power during the day when you're at work or otherwise driving your EV. Solar generates nothing at night when you need to be charging your EV. So if you have a couple (or more once the kids grow up) EVs you would need a MASSIVE battery pack to store up enough charge during the day to then dump into your cars at night. Maybe pumped hydro or something makes more sense if you have a hill you can use? Otherwise, unless you're retired or only drive at night I don't see how you go off-grid if you have EVs.
     
  6. brianman

    brianman Burrito Founder

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    Only charge at superchargers.

    /duck
     
  7. nwdiver

    nwdiver Active Member

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    Couldn't have said it better myself :wink:

    More to the point... if the objective is to displace fossil fuels then using the grid MORE can actually serve that purpose better than using it LESS. If you export; ~95% of that energy will displace other forms of generation. Storing it then using that storage later instead of drawing power off the grid is only ~70-90% efficient. Self-consumption, shifting your demand to when you would be exporting is the most ideal but you can only use so much power at a time. There's a 'sweet spot' between grid independence and grid use. Currently, for ~99% of DG owners it's irrelevant. That number will obviously shift as more and more solar exports seek consumption.

    My greatest concern for the future of the grid is that more utilities will adopt a punitive pricing structure intended to discourage PV rather than encourage PV owners to find that 'sweet spot'. It's not exactly in the financial interest of utilities to decrease dependence on fossil fuels. Without the production credits it would be economically beneficial for me to go off-grid... just not socially beneficial; I produce ~50% more energy than I consume, energy that is simply lost if I go off-grid and electricity will come from natural gas instead of my roof if I'm not exporting. :crying:

    I could still charge my EV off-grid... I would just need to manage how fast and when I charged more carefully.
     
  8. roblab

    roblab Active Member

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    Hmmmm. I don't think it's all that hard. You need a few batteries, a few dozen solar panels, a small stable (one Tesla). Can be done. I could do it.

    Most people don't need to completely fill the battery every day. I drive a few hundred miles a week, so my charge requirements might be 100 miles per day (I'm retired). Let's say that's a half pack, maybe 40 kWh. I have eight sealed AGM Maintenance Free batteries that can deliver 100 amp hours each at 12 volts for 20 hours. That's 1.2 kW per hour each, times eight is 10 kWh every hour. I never thought my batteries were "massive", but that's personal view point. That's eight feet by two feet floor area (on concrete patio) by a foot and a half above. They are in a closet, and there is storage above them. Doesn't sound massive.

    OK, Sounds to me like I am storing enough. Do I make enough? I have panels that put out about 11 kW. If they can do that for four hours, I can top up my batteries. Since there are many days I generate more than 4 hours, I have a grid connection so I can sell to the power company. Oh, yeah, that's not fair. Not "off grid". I do live on a hill, but pumped hydro is not as efficient as batteries, and more expenses. But why waste my power? Why not sell it?

    I am fortunate that I can sell power to the grid and buy it back at night. Where we live, there is not reliable wind, not usually windy at all. You probably have more wind. Wind doesn't work well for me, so I use more battery storage. I 'spect I could get even more batteries and do this easier. Might be cheaper than buying a wind generator, tower, more wiring, etc.

    But why would you go off grid at all, unless you have to? It can be done off grid, though. Massive batteries. Large solar array. I figure it would have paid for itself in about 8 years if I would stop buying upgrades!

    I want to see Tesla's storage system.
     
  9. nwdiver

    nwdiver Active Member

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    I wasn't referring to small scale residential wind so much as the large commercial farms. Wind turbines <10kW are ~3-4x the cost of solar PV even in areas with good wind resources. The large turbines >1MW can usually produce power for <$0.05/kWh.

    It just needs to be windy.... somewhere.... HVDC can send power ~1200 miles with >90% efficiency.
     
  10. strider

    strider Active Member

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    Well, my question was in relation to the discussions in this thread where power companies/regulators are discussing ways to dramatically increase the cost of installing grid-tied solar (wasn't there an article/thread about Oklahoma applying extra "grid charges" to residential solar users? So I was thinking along the lines of what I would take to go off-grid and avoid those extra charges.

    Thanks for the info on your system. I just had this crazy thought of needing two $40k Tesla packs sitting at my house.
     
  11. neroden

    neroden Happy Model S Owner

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    Oh, the grid is great, *if* the grid owner is being reasonable.

    I think one of the major motivations for going off the grid is badly-behaved utility companies, quite bluntly. Most people do not want to be dependent on an unpredictable organization with a bad attitude, and many are willing to pay extra to avoid such a dependence.

    A utility company which welcomes renewable energy and provides good two-way grid service -- moving electricity from the sunny side of the state to the cloudy side, and from the windy side to the still side -- will be popular and people will pay something for it. But if they show a bad attitude, or the grid power goes out all the time due to lack of proper maintenance, people will start trying to cut their connection, even if it isn't strictly profitable on a short-term financial basis.

    We're talking about issues of trust here; I've discussed this in many places.
     
  12. wycolo

    wycolo Active Member

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    Plan here is to build largish off-grid solar out in the field, large enough to charge one Tesla at a time until the sun goes down. Minimal sized battery bank, just enough to stabilize the system and not to time-shift kwhs. Thus car charging will *never* draw the battery bank below nominal voltage.

    Come evening looking at SOC in the Tesla, one can see if that might be enough for the next day's mileage needs. If not you can drive up to the house and plug it in (to the grid). Average driving is one 200+ mile trip per week, a few short trips and of course maintaining the SOC.

    If solar production > EV needs, one could then steal some energy for electric H2O heater and/or 1kw refrigerator using manual [either/or] switches connecting these appliances. The rest of the house could also be manually switched over to solar (or genset) during power outages, a rarity nowadays. But these 'inter'connections are not basic to the plan, just future opportunistic sideshows.

    The off-grid solar plant will attempt to satisfy the major electricity appliances, thus the monthly bill kept reasonable. There is currently nothing to motivate the rate payer beyond that.
    --
     
  13. 3mp_kwh

    3mp_kwh Member

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    Not addressing the "on-grid" incentive grid-based wind production might harmonize with, I'd circle back to the "off-grid" case with the understanding of how surprisingly fast utilities may be changing their pricing models.

    Whether OK, or the Salt River Project proposal (AZ) I commented on, not only are fixed "solar" fees being assessed as part of base rates, they are also drilling out the value of net-metering. In the case of SRP, or conceivably OK or any other place with good sun and cheap land, low commercial solar prices are becoming a weapon against on-grid residential solar customers. In 24 months, you might lose the $.12/kwh price you're getting, and see half that instead. Why not, as they argue, since utilities can now buy wholesale solar for about $.06/kwh.

    Conventional utilities have good reason to, and indeed seem to be, banking on the idea batteries and "cord cutting" won't succeed. It's a gamble, but also don't mistake how some utility commissions, as environmentally pre-disposed as they may be, do not want to see their ecosystem of tiered rates, measurable renewable progress, or simply their budget, shrink.

    Where I am, peaks of ~20GW load don't arrive until about 7PM. Wind/sun solutions don't balance as well with that demand.
     
  14. nwdiver

    nwdiver Active Member

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    I'm not suggesting that wind will eliminate the need for storage but it will reduce the need; Also... wind and solar rarely peak at the same time.

    California ISO
     
  15. SolarRyan

    SolarRyan New Member

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    This!
     
  16. AB4EJ

    AB4EJ Member

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  17. omgwtfbyobbq

    omgwtfbyobbq Member

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    Pumped hydro requires a lot of water and/or height. IIRC, for every kWh of storage one swimming pool's worth of water pumped up 30 feet is required.
     
  18. nwdiver

    nwdiver Active Member

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  19. TheTalkingMule

    TheTalkingMule Active Member

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    There's no such thing as a reasonable utility when it comes to distributed renewables, nor should there be. Distributed solar represents an existential threat to anything even remotely resembling the existing utility structure. All you have to do is look to Germany for your indication of what our future looks like. Tons of wind and solar have driven down the wholesale cost/price of electricity to nothing, yet the retail grid prices move even higher because profit margins must be maintained and every ounce of solar is three ounces of lost profit for the utilities.

    I would say it makes sense to remain connected to the grid, but not actively on the grid in the short term. Sure there may be a reasonable grid owner down the line with whom you'd like to do business, but until that day comes I don't see an economic or ethical reason to bypass the solar/battery/off-gird model if it's cheapest. Don't cut down your local telephone poles, but certainly don't be afraid to cut the cord at your driveway.
     
  20. omgwtfbyobbq

    omgwtfbyobbq Member

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    I can see that. Locally transmission rates are much more than generation, which may indicate an opportunity for battery storage, assuming those numbers haven't been fudged. The viability of the grid really depends on how much energy you need to store and how much that costs compared how much the utility charges for transmission.
     

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