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Efficiency - Built-in power losses

Discussion in 'Home Power and Microgeneration' started by James Baber, Sep 28, 2004.

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  1. James Baber

    James Baber Guest

    I see a lot of neat things here. I am a great fan of solar PV, and I have been
    successful in using it. Wind is good if location is appropriate. Small hydro
    can be good for some, and I would like to live where it was.

    What is common to everyone, 'efficiency'!

    By now we have all started using CFL (compact fluorescent lamps, you know those
    twisty things) lights. They use much less power (Watts) for the amount of light
    they produce, but even so they are very inefficient and waste 25-50% of the
    power they do use if they are measured for their powerfactor losses.

    Powerfactor losses account for 15% of all the energy paid for by the nations
    utilities customers on the average nationally. This can be proved by these
    utilities actually planning their capacity requirements on this figure. In fact
    if you are a major industrial or commercial user the utilities will charge you
    extra if you don't correct your own powerfactor. As far as the small consumer
    is concerned, the utilities have historically wanted you to buy more power, so
    they didn't tell you about these losses you do have to pay for.

    When I built my solar PV system, I went all through my home looking for things
    to do to reduce my needs and make the very expensive initial cost of the PV
    system as small as possible. This took about 1 year to complete and the I sized
    and designed my solar system. After I bought the hardware for the system, I was
    reading the inverter manuals.. (Really I do read instruction manuals as strange
    as that may be to some) .. and I tripped over the statement that the inverters
    had a powerfactor of 1.0

    I dug into my mental archives over powerfactor, since I knew I had NOT
    considered powerfactor in my planning. It had been in 1962 when I had last
    considered Powerfactor, but at that time I was designing power supplies for
    NCR's mainframe computers. As I recalled we were able save a significant
    savings in the AC power requirements for those mainframe computers by correcting
    the powerfactor losses from the power supply transformers with 60 cycle tuned
    capacitors.

    I proceeded with my solar PV, figuring the losses in my home were not
    significant, but I started looking for a powerfactor meter, and I eventually
    bought one that had a wattmeter and would record its readings for input into my
    computer. I didn't tell my wife how much, just that I was ($850.00).

    It is a neat tool, and like most techie types would, I started measuring things.
    The refrigerator, water heater, stove top, ovens, and finally the 240 input from
    the meter to the house.

    OUCH, the powerfactor was a miserable 0.81, with my PV solar turned off. It
    should ideally be 1.0 and this meant that in the year before I put in the PV I
    had wasted 4458 kWh of the 23,464 kWh I had paid $4,446.00 for in that prior
    year. This meant I had lost at least $844.00 to the bad powerfactor.

    The 4458 kWh used to offset the powerfactor loss would also work against
    whatever power I generated myself as well as any power I was planning to draw
    from the grid, so I decided to find some compensating capacitors to install to
    correct the bad powerfactor. It was not easy but I did, it cost $350.00, but it
    easily has paid for itself.

    The only problem with fixing this powerfactor loss, I had sized my PV system so
    that when my utility and I settle at the end of each year I had planed to pay
    about $400.00 on my bill (annually) to keep from giving them any credit. Last
    year that's about where we finished, but this year it looks like I'll have at
    least a $300.00 credit on my account that they just get to keep. Oh well I
    won't have to pay anything!

    --

    Jim Baber

    (see my 10kW grid tied solar system at "www.baber.org")

    1350 W Mesa Ave.
    Fresno CA, 93711
    (559) 435-9068
    (559) 905-2204 cell

    Email
     
  2. Jeff Wisnia

    Jeff Wisnia Guest

    <snipped>

    Why am I smelling the sweet aroma of spam here guys?

    Seems like Mr. Baber may be another sharp cookie trying to sell us Girl
    Scouts, only in this case it's power factor correction systems, as
    evidenced by the "Email an Order" button on his "KVAR page."

    I don't disagree with the potential money saving advantages of
    correcting the power factor of your home's electrical usage, but it
    would have been classier if Mr. Baber came right out and told us he had
    something to sell us.

    Power factor correction using capacitors has been around in industrial
    applications for as long as I can remember. This is the first time I've
    seen any advertisement for a home unit. Why is that? And, does a unit at
    that price level have the ability to adjust itself automatically so that
    it doesn't overcompensate when the AC and other motor loads are off and
    the remaining loads are already at or near unity power factor?

    I'd be interested in learning what his entire PV system cost, for all
    the equipment and a fair price for having it installed by contractors.
    It would be fun to calculate the payback time for that sort of
    installation, including factoring in the time value of money and
    maintenance.

    I didn't see any mention of energy storage as part of the PV system, so
    I presume that it will only make ac power when the sun shines. It does
    make sense to me that PV should be quite helpful for reducing the peak
    loads caused by AC systems which obviously work harder during the day
    than they do at night.

    Is it presently cheaper for power companies to generate electricity with
    PV systems? I don't know the answer, but I'd like to learn.

    Just my .02,

    Jeff

    --
    My name is Jeff Wisnia and I approved this message....

    (W1BSV + Brass Rat '57 EE)

    "As long as there are final exams, there will be prayer in public
    schools"
     
  3. Old Fangled

    Old Fangled Guest

    They aren't new -- even Consumer Reports looked at one. They don't save
    you any money at all, since the power meter at your house measures true RMS
    power and is unaffected by your power factor. It's only when you are a
    large industrial consumer do you get a meter that measures power factor as
    well as true power.
     
  4. If power companies bill us for kilowatt hrs, power factor is not an issue.
    If they say they are charging us kilowatt hrs, and actually charge us for
    kilovolt-amp hrs, that is NOT the amount of energy we are using and would
    be deceptive.

    Volt-amps may be the same as watts for DC current. But for AC current,
    volts and amps may be out of phase, so the actual power (watts) would
    usually be less than volt-amps. So power factor (watts/volt-amps) should
    not matter, except for sizing wire and circuit breakers for the amps.
    I use a "Kill A Watt" meter which was a fraction of that, but is limited
    to not much over 15 amps.
    What kind of plants are you growing with those fluorescent lamps and how
    much income do they bring in? Your theoretical loss is more than my
    annual electric bill (including heated waterbed and several PCs running
    24/7). For example my bill for period ending 8/20 was 440 kWh $46.10.
     
  5. Don Kelly

    Don Kelly Guest

    -----------
    This is nonsense.

    The watthour meter measures the "real" power that you used , not the
    apparent power.
    You got 23,464KWh which you paid for.

    The utility supplied 28968 kVAh. (23464/0.81- assuming 0.81 is an average
    figure))but you weren't charged for this- just for the real power. In your
    case correcting the power factor would NOT improve your bill but would mean
    that the utility would have a bit lower loss. You bought power factor
    correction equipment which will provide a small benefit to the utility
    (upstream of the correction equipment) and none to you except some possible
    voltage improvement at heavy load times. Note that at light load times, the
    capacitors will drive the power factor leading and, with regard to losses,
    0.8pf lead is no better than 0.8 lag.

    Note that, while you measured 0.81 pf, that measurement is good only for the
    instant that you took the measurement- your load varies through the day and
    so does your power factor-it could be better or worse than 0.81 at other
    times so an assumption of 0.81 pf may be quite wrong. .

    It is true, however, that the rate you are charged will include some effect
    of losses as part of the cost of delivering energy just as it includes the
    cost of equipment, salaries, profit, etc.

    For industrial loads there is metering in addition to kWh metering. This
    added metering is generally demand metering which will reflect both power
    factor and variable loading. In that case, as with your 1962 experience,
    there is a benefit to power factor correction but the breakeven point is at
    less than unity powerfactor (where incremental cost of improvement and
    incremental savings, over lifetime of use, are the same.).
    -------
    You may have wasted the money- unless you are being charged for demand as
    well as energy
    --------
    The gain you have made is not from your pf correction but from your pv
    system. Have you checked watts and pf at various times of day?
    .. --
    Don Kelly

    remove the urine to answer
     
  6. James Baber

    James Baber Guest

    Jim replies to Jeff:
    I have not sold ANY KVAR units, I have referred 1 party to my vendor. I have
    thought about selling them, but have not inventoried any. At this point I still
    am evaluating them as a major part of my entire program, but, they do appear
    effective at this point.


    Note, I didn't have an order form, or any specific way to order on my own site,
    just an invitation to email me for more information. Again I just referred the
    1 person I have corresponded with to my vendor, and do not know if that person
    has bought a unit.
    I don't understand why nobody has promoted any other similar product, except
    that capacitors of a size suitable for a whole house's loads are large and of a
    size that they require separate housing from the normal power distribution box.
    This box should be at least a NEMA 4 box and needs to be weatherproof.

    Also the installation of any electrical equipment attached directly to the power
    service should be installed by a licensed electrician, and it was my experience
    that it was difficult to find one willing to mess with a 30 minute job that was
    unfamiliar to them. The one that I did use for my own KVAR unit, was willing
    because I had him also installing time clocks on 2 electric (220V) water
    heaters. He was also new in the area, and was trying to build his business.

    Another point, the whole concept of powerfactor is so unfamiliar to 95% of the
    populace that anyone promoting the idea of correcting it, must be trying to con
    them, when obviously their power is OK now.

    This large part of the population doesn't understand the difference between AC
    and DC load reactance's (resistance's), and frankly they don't care and they
    don't want to know as long as the lights come on when they flip the switch.
    I have calculated it (payback) at about 5.5 years considering my loan costs and
    my total costs and the actual performance of the first 15 months of operation. I
    would be willing to go into in detail, but I've done that several times, all non
    design work has been done by my contractors as I am severely limited by my
    emphysema.
    The major points:
    COSTS
    (1,100) carpentry work (False wall, inverter cabinetry, minor roof mod.)
    ($81,000) primary PV system (panels, inverters, & installation cost.
    ($650) cost KVAR unit & 2 water heater timers incl'd.
    ($277) cost of converting to Time Of Use metering on grid for the meter.
    ($300) cost of new 1st Mortgage refinance that raised mortg. bal by 40,000
    Payment went up by $84.00, but will be paid off 3 years earlier.
    No change to tax assessment allowed under California Law.
    OFFSET INCOME or INTEREST
    $39,980 Rebate from the California rebate @ $4.00 per their wattage calcs.
    $6,300 One time 15% (net$) State income tax credit on our 2004 income tax.
    $4,000 Estimated annual utility savings (1st 6 without KVAR or TOU)
    1st 12 months actual = $450.30 the prior 12 months = $4,446.00
    next 3 months actual = (165.67) from the utility's statement HOT!
    $3,800 estimated savings in Federal & State income taxes (larger interest
    deductions because of new loan having larger early ded'n than orig.)
    I don't personally "store" any power. I am on Net grid metering, so any power I
    do not immediately use is exported directly to the grid, and I do draw power
    back at night and whenever I need more power from the grid. So in effect I do
    use the grid like a battery, but it only costs me a $1.37/mo. service charge,
    unless I use more than I produce. (MUCH cheaper than batteries) Under this net
    grid plan I will lose any outstanding $ credit (earned at the sam kWh rate as I
    would have to pay) I might have at the annual settlement.
    Interestingly enough I am making an average 28.94 kW out of the average 49.68 kW
    that I generate daily during the noon to 6 PM peak usage hours. So this really
    helps my utility.
    --

    Jim Baber

    (see my 10kW grid tied solar system at "www.baber.org")

    1350 W Mesa Ave.
    Fresno CA, 93711
    (559) 435-9068
    (559) 905-2204 cell

    Email
     
  7. Jeff Wisnia

    Jeff Wisnia Guest

    I may have come on a bit too strong James, but when I saw you'd cross
    posted to a lot of other newsgroups and then noted that you hadn't
    posted to this group before (at least in the last month) I "smelled SPAM".

    And you do/did have an "Email an Order" button on your "KVAR page", but
    I didn't bother to click on it.

    All that said, a lot of folks have responded to this thread to state
    that "whole house" power factor correction will have no direct effect on
    the typical homeowner's power cost, because the usual residential meters
    measure RMS power, which do not measure or record anything concerning
    the power factor of the load they are metering.

    You may well have a more sophisticated metering setup from PG&E, where
    your two homes' overall power factor may in fact directly affect your
    bill. That wouldn't suprise me given that you have a system where you
    can in effect "run the meter backwards" when you are putting power back
    on the grid from your PV system.

    If you know, or can find out from PG&E whether your metering takes power
    factor into effect I'd like to learn.

    Thanks for all the other info.

    Cheers,

    Jeff


    --
    My name is Jeff Wisnia and I approved this message....

    (W1BSV + Brass Rat '57 EE)

    "As long as there are final exams, there will be prayer in public
    schools"
     
  8. Don Kelly

    Don Kelly Guest

     
  9. Don Kelly

    Don Kelly Guest

    The key question is "are you being billed for kWh only or do you have a
    billing which takes into account power factor or, more likely , eak demand.
    The latter is used for industrial/ commercial loads but, generally domestic
    loads simply have kWh metering- in that case pf correction gains nothing
    dollarwise- that is the reason you haven't seen it promoted.

    By the way, I am very familiar (actually I would hazard a guess that I am
    more familiar than you are with it ) with the concept of power factor and
    its correction- that's why I am questioning the basis of your economic
    analysis.
     
  10. Ted Wood

    Ted Wood Guest

    I just got my electricity bill and the meter reading shows that we used
    684kWh for the month of August. There is a "Total Loss Factor" of 1.0422
    that is applied to the 684kWh giving an "adjusted" usage of 712.86kWh.

    What is my actual usage? Is the "Total Loss Factor" the same thing as
    powerfactor?

    Ted Wood
     
  11. Ted Wood wrote:
    ....
    Your actual usage is what appears on your meter, 684kWh.

    "Total Loss Factor" is not the same thing as power factor.

    "Total Loss Factor" is an estimate of the amount of power that is lost
    through the transmission lines before it gets to your house. They figure
    this by adding up all the power they purchased (or otherwise obtained)
    from power generators and subtracting all the power they actually
    delivered to customers. They then divide this out to figure out what
    percent of energy (on average) was lost in delivery and apply that to
    your bill.

    Previously, this was simply part of the price of the power you purchase.
    This way they have "passed the cost" on to you through a line item and
    thereby increased the rate you pay without actually having to go through
    the rate increase. Expect to see a lot more of this nonsense in the
    future because it's a way to sidestep regulation.

    Anthony
     
  12. Why is there anything to evaluate and what appears to be effective? I
    have been in the electric utility business for 40 years. Power factor
    correction has no value in residential applications since the customer
    is only billed for real energy consumption. With the companies that I
    worked for, there was a reactive penalty only when the commercial or
    industrial user exceeded a threshold. With one supplier, there was no
    penalty but we had the option of either jaw boning the user or
    disconnecting him.




    Regards,

    John Phillips
     
  13. James Baber

    James Baber Guest

    Jim replies to John:

    John, I am still "evaluating this" because I have had a lot of conflicting
    information. I do show an improvement in my system when I have the correction
    capacitors in the circuit. However, this may be because I am producing so much
    of the total power I am using myself in the solar PV arrays I have installed now.

    I have been told that since My bad powerfactor was measured without the PV, the
    correction is applied to the direct benefit of my own PV production, thereby
    making it more productive. This improvement actually does end up as a very
    significant gain in the power I export to the grid, which means I have more
    credit available in my net account. This power appears as an improvement over
    all and is even further impacted by the fact that I am on a Time Of Use rate
    structure. This "gain is exaggerated since it occurs at the time of peak
    inductive loading (air conditioning).
    --

    Jim Baber

    (see my 10kW grid tied solar system at "www.baber.org")

    1350 W Mesa Ave.
    Fresno CA, 93711
    (559) 435-9068
    (559) 905-2204 cell

    Email
     
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