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Feeding solar power back into municipal grid: Issues andfinger-pointing

Discussion in 'Home Power and Microgeneration' started by Home Guy, Apr 4, 2011.

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  1. Home Guy

    Home Guy Guest

    We have a residential energy program here in Ontario (Canada) that I
    really don't agree with (called the Micro-Fit program) where the
    electricity from roof-mounted solar panels is purchased by the
    provincial power authority (OPA) at something like 80 cents per kw-hour
    (a crazy-high fee that will have to be subsidized by somebody - ie the
    general population, taxpayers, etc).

    I believe all the details for this can be found here:

    A neighbor of mine had a free evaluation done on his home to see how
    many panels situated on his roof would generate how much electricity.

    The problem he's facing is that two different levels of power
    distribution (the city-owned municipal owned and operated company, and
    the provincial or regional power supplier or distributor that either
    supplies the electricity to our city or owns the high and medium-voltage
    lines and sub-stations where the electricity is stepped down) are
    pointing the finger at each other by stating that there is a capacity
    problem caused by the other as the reason why his solar panel
    installation (which he hasn't yet contracted to be installed) can't be
    connected to the grid.

    It's my impression that any electricy that he'd be generating would
    essentially be 2-phase 208 volts (ie - identical to the service that
    enters our homes) and this electricity would simply be inserted or wired
    in parallel through a meter to his existing electrical service. I don't
    see how the capacity (or lack thereof) of the sub-station serving our
    corner of the city plays any role as to whether or not our local grid
    can accept and utilize the estimated 5 or 6 kw that his panels are
    likely to put out at maximum.

    This issue has recently come up as indicated by this:

    The OPA is proposing that all new microFIT applications submitted on or
    after December 8, 2010, would need an offer to connect from their local
    distribution company before the OPA issues a microFIT conditional offer
    of contract. The proposed rule change can be viewed here.

    According to this document:

    Page 18 shows the most likely connection scheme - which is to connect
    the Microfit PV project to the grid on the customer's side of his load
    meter (ie - "behind the meter" - the load meter that is).

    My basic thesis here is that I think any argument about the capacity of
    the "grid" (where-ever or what-ever the "grid" is) being at or near
    capacity and thus the application for eligibility to get the green light
    for approval is bogus. We are talking about installations that can't
    generate more than 10 kw - and more likely would only generate 5 or 6 kw
    on a mid-summer day, with the bulk of that energy being consumed by the
    home owner's own AC unit (I'm sure) with little or none to spare to be
    injected back into the neighborhood grid.

  2. vaughn

    vaughn Guest

    I would certainly be tempted by that deal. That's better than the long-term
    return of the stock market. There are, however, other factors. I would need to
    be convinced that the panels 1) would likely survive a hurricane and 2) their
    installation would not damage my roofing system.

  3. Keep an eye on your solar array my friend, those things like air
    conditioners around here are being stolen at an increasing rate.
    People install them at their remote cabins or camps only to return
    to a powerless abode. Thieves will steel them while a home owner
    is asleep at night!

  4. Home Guy

    Home Guy Guest

    Under the terms of the Ontario Microfit program, you (the home owner)
    with a (typical) 3kw to 6kw solar array, will be paid 80 cents /kwh for
    20 years. The going rate for buying electricity in this market at the
    residential level is (when you factor in all the various transmission
    and delivery costs) about 15 cents / kwh.

    You are paid 80 cents / kwh for *any* electricity leaving your array (a
    billing meter is installed right after your invertors). It doesn't
    matter if your own home (AC unit, etc) will suck 100% of that solar
    energy with none of it going back into the grid. In fact, it's probable
    that on that hot summer day that your home will still be pulling energy
    from the municipal grid - just not as much because of the contribution
    from your own panels.
    There has been some mention of a PF (power factor) issue when it comes
    to these panels.

    But still - you can't push more electricity onto a network than the load
    is asking for (given that your invertors are functioning correctly I
  5. Guest

    I believe that 10 kw is the maximum size for micro-fit pricing,
    in Ontario. per property.
    .. now available for roof-top only - formerly rural free standing
    tracking were elegible. ?
    Each individual property/service will have specific limitations -
    .. there's old crappy services out there ! fer shur.
    but - BIG but - I would demand hard facts from my distribution
    company - about any specific "grid" limits - that would be
    restrictive to a 10 kw solar ...
    Don't let them snow-job you - by saying they have to now plan for
    all your neighbours installing 10 kw solar ...
    My understanding is that these micro solar will be connected
    through their own meter ? so the property owner will not be able to
    affect the "sales" by adjusting his demand....
  6. Guest

    I guess , not.
  7. Tom P

    Tom P Guest

    Up front - you should in any case arrange for your building insurance to
    be extended to include cover for the panels. Why? Because if it does
    blow away in a gale or catch fire or whatever and they don't know about
    it, in the worst case the insurance could refuse to pay for the damage.
    The additional insurance for my roof panels costs here (Germany) €88
    per year. There are cheaper offers but I preferred to use the same
    company for all the building related insurance to avoid any finger
    pointing problems in the event of a claim.
    It is possible that the insurer might demand that the roof structure be
    checked by a surveyor before you start work. As far as any damage to the
    roof during installation, a reputable installation/roofing company
    should in any case have professional liability insurance.
  8. Tom P

    Tom P Guest

    The bark may be worse than the bite. The company who did my PV
    installation also did the entire beaurocratic paperchase for me. They
    sent me a whole pile of application forms to fill in, and I sent them
    all back with a limited power of attorney to let them get on with it.

    I can understand that the grid operators need to know how many PV
    installations there are and how they are all connected.
  9. Home Guy

    Home Guy Guest

    Correct. Anything over 10 kw falls into a different program - called
    "Fit". But given the geographic area of Ontario (mostly above 42
    degrees latitude) you'd need a pretty big house with no tree shading to
    generate anything close to 10 kw.
    The microfit program really only started in late 2009. Up until some
    point in 2010, you got 80 cents / kwh regardless if it was roof-top or
    ground mounted (basically the early program documentation wasn't clear
    enough or didn't differentiate between the two styles). It was only by
    mid 2010 that they announced a different price rate for ground mounted
    panels - I think it's 60-odd cents. Anyone that already had
    ground-mounted was grandfathered in at the roof-top rate (80 cents).
    It's a scam, really. The local and regional electricity providers (we
    generally call the electricity service the "hydro" service, because
    historically Ontario's electricity was first generated by hydro-electric
    facilities in Niagara falls) does not really want to see these solar
    panels on residential rooftops - I suppose they don't need the hassle of
    new sources for problems with the grid, power-factor issues,
    competition, etc.

    When you get denied to connect your panels to the grid, it's not really
    based on the wiring between your house and your distribution transformer
    (nobody comes out to look at that). The denial is based on the capacity
    or condition of the regional substation serving your corner of the city
    - something for which I can't really imagine how it's involved in the
    transmission of the energy your panels are going to put into the grid.

    The fact is that unless you turn off your AC unit on the sunniest /
    hottest days of the summer, the energy your panels are putting out will
    be 100% consumed by your own home's load, with none of it going out to
    the grid. But you'll still get paid 80 cents / kwh because the payment
    meter is placed right after the invertor output before it goes anywhere
    You're sort of correct.

    Yes, the panels have their own meter. But nothing the owner can do with
    his home's load will affect billing or revenue from the panels - because
    he's paid for any and all kw being generated by the panels - even if
    none of those kw are technically leaving his own home.
  10. Guest

    As long as the government can rob peter to pay you.
  11. Winston

    Winston Guest

    harry wrote:
    Why does this remind me of the famous Whimpy quote:
    "I'll gladly pay you Tuesday for a hamburger today" ?

    "From Popeye cartoons. Line often uttered by Popeye's portly friend
    Wimpy. Of course, "Tuesday" would never come, and so Wimpy
    constantly secured himself a free lunch. Thus the line is used to
    jokingly indicate that one would like to "borrow" something without
    any real intention of ever paying you back."

  12. daestrom

    daestrom Guest

    One issue that utilities worry about is the available fault current.
    The breaker main in a typical home might be able to safely interrupt as
    much as 10 kA. The current of a dead short in your home is a function
    of the sources feeding it. If the total is less than 10 kA, the breaker
    opens and everyone's safe. If the sources could feed more than 10 kA,
    the breaker may fuse/melt and the fault will continue to draw current
    and your house burns down.

    So when adding new sub-station equipment and generating units, they have
    to calculate the available fault currents and make sure it's still under
    the breaker/protection equipment capabilities.

    All that being said, I can't honestly think a small grid-tie PV
    installation would make enough of a difference to be a problem. Worst
    case is your neighbor has a fault and the combined current from the
    utility and your PV setup exceeds his breaker's interrupting capacity.

    But a good EE could sharpen his pencil once and do the calcs and
    probably find there is a wide margin between what the pole transformer
    can supply to a fault and what your PV system would supply. They're
    probably just to worried about their liability to bother.

    P.S. Maybe if every household in a whole development had such a
    microFIT installation? I'd have to see the numbers though to believe it.
  13. daestrom

    daestrom Guest

    As I said in another post, one concern is how much fault current can be
    drawn from the system. If there is a largish substation and several PV
    generators on it, then the total current feeding into a fault *could* be

    If that fault happens to be in someone's home and it exceeds the
    *interrupting* capacity of their main breaker, the breaker may not be
    able to isolate the fault and their house burns down.

    It would seem to me that it would take a large number of PV
    installations to really raise the possible fault current very much
    though. Maybe they just don't want to pay an engineer to figure it out.

    P.S. Note that the available fault current has nothing to do with the
    circuit breaker's trip setting and only loosely related to the
    individual inverter output capability.
  14. Guest

    There is still a peter being robbed at the government's insistence, dope.
  15. Vaughn

    Vaughn Guest

    Well, we've degenerated to name-calling. I don't expect we'll see much more
    useful discussion from this thread.

  16. Guest

    I can't help it if you don't like facts. harry *is* a dope.
  17. m II

    m II Guest

    Please be informed that the Josepi clown has been forging my username
    for a few weeks now. His provider is doing nothing to stop the forgeries.

    Check the headers when in doubt. It's times like these I wonder about
    the maturity levels of some, no doubt very ill, people.

  18. m II

    m II Guest

    Please be informed that the Josepi clown has been forging my username
    for a few weeks now. His provider is doing nothing to stop the forgeries.

    Check the headers when in doubt. It's times like these I wonder about
    the maturity levels of some, no doubt very ill, people.

  19. daestrom

    daestrom Guest

    Got some numbers/calculations to support that? Is that including the
    next door neighbors with their PV installation?

  20. Han

    Han Guest

    I have no idea how it works exactly, but here in North Jersey PSE&G has
    been putting up solar panels on their (I think) utility poles. Each one
    is maximum 200 Watts at 110V, feeding directly into the grid the poles
    carry. This is a link + picture in another town not too far away (1 line):
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