Efficiency - Built-in power losses

[James Baber]

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!

[m Ransley]

America does not use CFL s A bill was dismissed making CFLs the light of choise by BUSH and his NON ENERGY policy... CFLs are great as are V6 motors and 90 + efficient heating systems...

SO WHY ARE THEY NOT LAW????????????????? BIG BUSH BUSINESS

[Jeff Wisnia]

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

[Old Fangled]

Jeff Wisnia wrote in news:tLidnU2ADudcbcTcRVn- [e-mail]:

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.

[David Efflandt]

On Tue, 28 Sep 2004 18:48:17 GMT, James Baber wrote: (parts snipped)

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.

[Jeff Wisnia]

Thanks, I wasn't aware that residential power meters were true RMS meters. I cynically assumed that the greedy utility companies would have done it the other way around.

So I now see why adding a single power factor correction device just after the meter would benefit only the utility company by reducing the current flowing in their wires and its attendant energy losses, and in the aggregate decreasing the maximum current the utility company has to be able to supply.

You could obtain miniscule savings by adding power factor correction capacitors right at the major power hungry inductive devices in a house, like an air conditioning compressor motor. That would slightly reduce the average current in the conductors leading from the meter to those devices, it would thus correspondingly reduce the power dissipated in heating those conductors.

Anytime you turn electricity into heat in your house you're paying the utility company for it, and paying them doubly if your air conditioning system has to move that heat outside.

But, using those power factor correction capacitors at the inductive devices would be "a long run for a short slide", wouldn't it?

Jeff

[Don Kelly]

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 [e-mail] remove the urine to answer

[nicksanspam]

More like "another 30 percentedly" :-)

Nick

[Jeff Wisnia]

Not if your AC system is as old as mine...

Jeff

[James Baber]

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.

Jeff Wisnia wrote:

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.

[Jeff Wisnia]

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

[Don Kelly]

---------- Agreed -note that it is "average" power (per cycle) , not "rms" power. About the only place where rms power is legitimately used is in sizing of motors for varying loads. just a nit pick. What is below makes sense.

[Don Kelly]

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.