"Power Factor" and devices
that claim to save energy by fixing it
Last
update: January 2010
NOTE:
After writing the article below, a reader wrote
in and claims to have measured savings with a
power factor device through the only test that
matters: clocking your electric meter. While I'm skeptical, given
the extreme reader interest in these devices, it's clear
that I need to test one myself to put the matter to rest once and for all. I won't have time
to do so until this fall
(2010) at the earliest, but when I do I'll report the results
here. In the meantime, below is my position on power factor devices, until I see good evidence to the contrary. And again, the only evidence that is acceptable is a before and after test, clocking the actual utility company electric meter each time.
Before I give the technical explanation about
these devices, let me give you the summary:
These devices won't save electricity in your
home. Don't waste your money on them. They do
correct your power factor, but utilities don't
charge home users for bad power factor. You
weren't paying a penalty before installing the
unit, so you won't see any savings after you put it
in.
Now, some commercial customers are
billed for bad power factor, if their power factor
is very bad. For those users it might
make sense to install PF-correction equipment. But
not home users.
Besides the fact that these things don't work
for home users, 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.
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. But since home
users aren't billed on power factor, there's no
savings to be had.
And even if the utility billed home users for
bad power factor, modern appliances already have
this kind of power-correction built-in. For
these appliances, there's nothing left to
"correct". Consumer
Reports says the average American home already
has a power factor of 90%, which would make the
maximum savings close to only 10% (if the utility
actually charged you for the power factor penalty,
which they don't).
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.
Another writes:
Our residential meters don't measure
reactive power. You can't save money
by plugging in a reactive power correction
device.
Consumer Reports also confirms
that residential users don't pay for bad
power factor.
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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. Period. (Yet clueless sales
reps and customers keep offering to send me their electric bills, as
though that wasn't completely useless.) 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.
Some of them have videos showing some kind
of meter connected that shows some kind of
reduction. This is also the wrong test,
because the question isn't whether the power
factor is corrected, it's whether there's a
reduction at your electric meter. Okay, so one of
these companies has a video showing it connected
to an electric meter -- sitting on a
table! Not an actual electric meter in use,
installed at the house. No one has ever
produced a video of an actual installed
residential electric meter showing a
decrease in usage with one of these devices
connected. Why
on earth not, when it's an easy test to do, and when it's the best
proof available? Probably because the devices don't work.
Here's another thing: 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 several thousand 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.
For nearly ten years I had an open offer for manufacturers to send me their device to test, but no one ever took me up on it.
As of January 2010 I'm retiring this offer because I won't be able to
test one until fall since I'm traveling, and at that point I'm just
going to buy my own to test it.
By the way, last summer I went to the
website of the most well-known power factor box maker, but I
couldn't find any guarantee mentioned anywhere
on the site. I called and they said they'd email
it to me, but what I got was some barely
literate rambling jargon that wouldn't pass as a
guarantee in any court on this planet. I wrote
back and asked if they'd agree to a simple
statement (something like they "guarantee that
the unit will reduce energy consumption as shown
at the residential electric meter"), but they
didn't write back. I called, we traded
voicemails, but then after my last message I
haven't heard from them.
My test of two different plug-in units shows
that they don't work
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.
(If you have a blog or website and would like
to test this unit yourself and report on it,
send your mailing your address to
and I'll mail it to you.
Please don't send any
other kind of email to that
address.)
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.
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