About 18 months ago I warned about power factor correction devices that are being heavily marketed in Southwest Florida. These “energy saving devices” do nothing to reduce your electricity bill, which is exactly what they are advertised to do.
Despite the well known fact that this technology has no place in household energy savings, the myth persists. I recently received an advertisement in the mail from a licensed electrical contractor pitching these things. Just yesterday I received an email from a manufacturer pitching an energy saver to our company. What was alarming is that it didn’t come from China, from where most of the others are coming these days – it’s being manufactured right here in Okeechobee, FL!
Energy Saving Devices Debunked
This KVAR “Energy Saving Device” spotted on eBay will do nothing to save your electricity in your home.
These products are marketed under slick names like Super Saver 2000, and Electric Buster 1200 (names changed to keep my lawyer happy). Manufacturers mass produce these things and allow small companies to private label them, giving rise to all kinds of corny names.
The pitch is usually that for a few hundred bucks, installed, these devices will drop your electric utility bill because you have a bunch of motors in your house (pool, air conditioning, refrigerator, etc) and motors are “reactive” loads that waste power. On it’s face, that is essentially a true statement. The important thing they leave out is that you are not billed for that wasted power. This also known as “apparent power” as opposed to “true power” for which you are billed. The utility company just delivers the apparent power required to make up for the inefficiency of these motors.
It’s hard to believe, but that’s a fact. You don’t have to pay for this idiosyncratic inefficiency in your home. You are sent power in kilowatts, which are billed in kilowatt-hours (kWh). Go ahead and check your utility bill. The utility company has to produce what called volt-amps, known as kVA to deliver power to you. The relationship between kW and kVa is the power factor that these devices are said to correct.
The Math
Let’s do a simple example. Let’s say you have a pool pump that draws 1 kilowatts and it has a power factor of 0.9. The utility needs to produce and deliver 1.0kW / 0.9 = 1,111 kVa. The device manufacturers would like you to believe that you have to pay for 1,111 watts of power. That is not the case – you are billed only for the true power consumed – 1,000W or 1kW. The difference is the utility company’s problem.
Now on the utility side of the meter, power factor correction could be beneficial to the power company. Again, this is not your problem, and you are not billed for the power factor loss.
Incidentally, these devices are sometimes called KVAR devices, describing reactive (the R in KVAR) electric loads in your home with motors.
If you want to read the long and boring technical answer, we have it. This National Institute of Standards and Technology study debunks power factor correction in homes. It concludes that, “…the homeowner’s electric bill will not decrease because, as noted above, the cost is determined in part by the product of current, voltage, and power factor. That is, as the current from the power line is reduced by the introduction of capacitance, the power factor is increased and the product, I x V x PF, remains essentially the same.” (emphasis added)
How KVAR Devices Work
Power factor correction is done by adding capacitors to a circuit. These capacitors store energy like batteries in a way. They shift the demand for electricity a fraction of a second to correct for the power factor deficiency. As a result, the power factor increases.
This is a very simplistic explanation, so before all you engineers jump all over me in the comments below, let me say that this is geared toward the everyday consumer.
In a residential setting, a kVAR device will actually cost your money, not save you money. This is because the capacitors are not 100% efficient. You will lose some of the electricity you pay for as heat generated by the device. Sure, the device will correct power factor perhaps, but that won’t save you any money!
Business Case for Power Factor Correction
This commercial power factor correction equipment from Rapid Power Management does save energy in the right industrial setting.
Now some businesses do benefit from power factor correction because they are billed for poor power factor if it exists. This is normally in a manufacturing or industrial setting where large three phase motors are present. The little residential KVAR devices will do nothing to correct this. You need big capacitors and more sophisticated gear to measure and correct commercial power factor issues.
Commercial power factor correction is best left to qualified commercial electrical contractors in coordination with the utility company.
The Environmental Argument
In theory, a residential KVAR device saves energy at the utility level. That would result in less fuel being used to produce energy. Therefore, the utility company should have a lower carbon footprint. However, the energy savings would be so minute that the cost would not outweigh the benefit.
Any benefits gained from use of a KVAR device also need to be weighed against the carbon footprint of manufacturing the device itself. In the end, there is no environmental benefit that’s worth pursuing by installing these devices.
Should I Buy an Energy Saving Device
Absolutely not. Run the other way. Anyone who tries to sell you one of these devices is a charlatan selling snake oil.
If you think a little box installed by your circuit breaker panel is going to save you 10%, 20%, or more on your electric bill, that should strike you as too good to be true. If it worked, everyone would do it, right? Surely it would be a standard feature on every home built.
Don’t get sucked in by a slick salesman or glossy advertisement.
You will waste your money on the device and installation, and waste more money on the extra electricity consumed. DO NOT purchase a KVAR or energy saving device for your home.