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"Power Factor" and devices
that claim to save energy by fixing it
Before I give the technical explanation, let
me give you the summary: These devices won't
save electricity in your home. Don't waste your
money on them.
Besides the fact that they don't work,
there's something else about them that rubs me the
wrong way: Many people are just looking for a
quick fix, some device they can just buy and plug
in so they don't actually have to make any effort
to conserve energy. Please, let's move beyond that.
Saving electricity really isn't that hard, and the
amount of energy a household could save by not
being wasteful is tons more than could be saved by
one of these little plug-in devices, if they worked
(which they don't). So let's stop pinning our hopes
on tech scams and instead simply use less
electricity.
 Okay,
so let's talk about "power factor". I'll use
BC
Hydro's explanation of this concept:
Power factor is a
measure of how effectively your equipment
converts electric current from [the utility
company] to useful power output, such as
heat, light or mechanical motion. Low power
factor costs you money.
There are two kinds of
power:
- Usable power called
kilowatts (kW)
- Reactive power
called kilovar (kVar)
The ratio of your
usable power consumption to your reactive power
consumption determines your power factor. Some
electrical equipment, such as motors and
transformers, require both types of power. Power
factor gets smaller as reactive power increases
in comparison to usable power.
There are a number of devices which increase
the power factor or recycle the reactive power to
try to save energy. What's more, this is
supposed to make your equipment run cooler and last
longer. The devices either plug into an empty
electrical outlet, or you have an electrician
install it at the service panel.
Here's why I don't think this saves any
appreciable amount of electricity:
A utility
company employee writes:
I work for a utility in Ontario
and we have tested these devices in our
shop, and these devices are a scam for
residential billed customers. They
do correct the power factor but since
residential customers are only billed
on kw.h they do nothing to reduce a
customer bill. That is loads use watts,
and residential customers are billed on
watts, so it doesn't matter what the PF
is. Our tests not only proved this but
that these devices actually use a small
amount energy, which ironically drives
the customer bill up.
PF only
comes into play with larger commercial
customers who are billed
on Peak Demand. The theory is that
customers use Watts and the utiltiy
supplies VA, so for the same load
(watts), the lower the PF the more the
utility must supply in VA. To combat
this the utility bills is the higher of
Watts or 90%*VA, thus the customer is
charged more for a low (bad) PF, thus
they can reduce their demand charge by
raising (or fixing) their PF. PF is
lowered by inductive loads, thus adding
capacitance raises it. These little
expensive devices are just
capacitors.
I read the white papers on these
devices, and they did not report
anything that was untrue, but the
advertising is very misleading.
Some of the technical people at our
work were fooled, until it was
explained and our results revealed.
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Only for motors and transformers. The
reduction isn't for every device in your home,
only things with motors, transformers, and
fluorescents which need reactive power.- Modern appliances have power-correction
built in. Ancient appliances were wasteful,
but modern appliances (like fridges) already
have this same kind of power-correction
technology built-in. For those devices, there
are no more savings to be had.
- People from two different utility
companies wrote in to tell me that these devices
don't work for home users. The person from
Ameren in Illinois says, "Our residential meters
don't measure reactive power. You can't
save money by plugging in a reactive power
correction device." And Greg from Canada writes,
"I work for a utility in Ontario and we have
tested these devices in our shop, and these
devices are a scam for residential billed
customers. They do correct the power factor but
since residential customers are only billed on
kw.h they do nothing to reduce a customer bill."
See his more complete comments at right.
- I've never measured any savings when
testing an actual unit. No manufacturer has
ever sent me a unit to test (could it be they
know the product would fail?), and the ones I
purchased myself or which were sent to me by
readers failed to save any energy.
Now, commercial users with lots of
machinery have a greater potential for savings,
but it depends on how much machinery they run and
how much reactive power it needs. The only way to
find that out is to get a demo from a vendor
showing you before & after figures for energy
consumption.
The proof of the pudding is in the eating
The websites for products like these
extol supposed testimonials from residential
customers, who are simply looking at their bill
month over month. Frankly, that's a
ridiculous way to evaluate whether the product
works or not. Energy use from month to month can
vary for all kinds of reasons.
The only meaningful way to
test one of these products is to clock the
electric meter before and after the product is
installed, with the same exact devices running
in the house. That's the only kind of
test I will perform, and that's the only kind of
demonstration I'll accept.
Power factor box manufacturers are always
trying to impress me with alleged testimonials
from their supposed customers. But in fact
nothing could impress me less. Those customers
almost certainly didn't do the proper kind of
test, and I have no way of verifying their
honesty anyway. In short, if I don't see it
myself firsthand, I'm not buying it.
If these devices really worked, then
companies would be falling all over themselves
to get me to test them or to demo them for me so
they could get the free advertising from me.
I get thousands of visitors to this site every
day, why wouldn't they want that? The fact that
I don't hear from them in and of itself is
telling.
It's not because they don't know about
this site. It's the #1 site on the net for
saving electricity, has been mentioned in
Newsweek, and frankly, if you're in the
electricity-saving business, you know about it.
Also, when a manufacturer writes to me to gush
about how much energy their product saves, I
say, Fine, send me one to test. And then I never
hear from them again. I was going to link to the
last manufacturer that happened with but I just
tried to check their site and it crashed both my
browsers.
So, all you companies with power-factor
devices, I'll be happy to accept a device to
test, or to have you demonstrate it to me in
Austin, Texas. My address is: Michael
Bluejay, P.O. Box 8600, Austin, Texas
78713-8600, or you can email
me.
Readers, I will not go out and buy any of
these products to test them because it's silly
to test dozens and dozens of products which I
have no faith will work properly anyway.
Besides, if they really worked, I expect the
manufacturers would be eager to have me test
them.
One reader bought a unit and sent it to me
to test, and I'm happy to do that, but realize
that you can perform the same test
yourself:
- Turn on everything in your home.
- Go outside and clock your electric meter.
(See how fast it spins.)
- Plug in or install the power factor
device.
- Clock your electric meter again.
Make sure that nothing changes before and
after you install the device. That is, make sure
the fridge doesn't kick in or cut off between
meter readings. Was there a difference in how
fast your electric meter spins? How much? If it
spins 10% slower with the device installed then
congratulations, you're saving 10%. But if
there's no difference then you
save...nothing.
Anway, Gen Russell of Australia sent me an
"A2
Intelligent Every Saver".
Supposedly you just plug it in and save "up to
35%". So I turned on every light (fluorescents),
the window AC units, the microwave oven, and
cranked up the refrigerator. I went outside and
clocked the electric meter to see how fast it
was spinning. Then I went inside, plugged the A2
device into the wall, and went back outside to
clock the meter again. No change. Let me repeat
that: No change. Meaning I showed
zero savings with this device plugged
in.
The instructions for the device didn't say
whether it had to be on the same circuit as the
appliances, implying that any circuit was fine,
but just in case, I plugged it into several
different circuits. No difference, no
savings.
Some years ago I bought a similar device
from Home Depot called "EnergySmart
PowerPlanner", which claimed to save up to 23%
on my refrigerator's use, but which in my tests
failed to save any energy at all. Later
the
CPSC issued a recall on many of these models
for safety issues. Eventually the company went
out of business.
 When
I heard about this device I repeatedly wrote to
them asking for a unit to test, but I never
heard back from them. Maybe they knew it didn't
really work. So I finally just went out and
bought one but couldn't measure any savings even
when testing it on an ancient Whirlpool
refrigerator. The device should have worked well
since older fridges are much less efficient than
newer ones. After 100 hours each with and
without, the fridge actually used 9.6%
more electricity when the device was
installed. Looking at just how many watts the
fridge is pulling when the compressor is
running, the device dropped the load from 195
watts to 189 -- about a 3% reduction. Apparently
the compressor had to run longer, which is why I
used more electricity overall. Even if the
compressor doesn't run longer, a 3% savings on a
modern fridge would be about 15 kWh a year -- or
$1.50. The device itself cost $30. EnergySmart
listed the results of "studies" on their website
which purportedly proved their product works,
but they provided nearly no data on the studies
themselves (such as the age of the refrigerator
that was used), much less a the full text of the
study or even a link to the study's authors..
Chuck
Wright tested the PowerPlanner and also
failed to realize any meaningful savings. Like
most magic "plug-it-in-and-save" devices, this
product seems like more hype than benefit.
Devices that claim to save energy by
reducing
surges also don't save squat. In
short,
I know of NO
device that will save household energy overall
simply by plugging it in or installing it at the
panel.
I'm certainly willing to revise my opinion if I
can measure savings in a hands-on test, but until
then, my position is that if you want to save
energy, you do it the obvious way: use
less.
Last update: September
2008
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