Phantom Loads

Of all of the electrical items that you can have in your home among the most detrimental to the health of your energy system are Phantom Loads. I don't mean those awful leftover bowls of Halloween candy that haunt us this time of year. I mean those tiny gremlins with the glowing green eyes that peek out at us in the dark of night from every corner of our house.

We all have them (well, OK, I confess, I don't, but I had to learn to get rid of them) and we seldom notice them, but in a renewable energy home they can gobble up a considerable amount of the energy we have planned for other uses.

What are they? Digital clocks, answering machines, TV sets, VCRs, stereos and any device that gets its power through one of those little transformer "cubes" that plugs into the wall. They are called Phantom Loads because they sit there in our homes, out of sight and out of mind, and consume small amounts of electricity 24 hours a day, 365 days a year.

But if it's a small amount, you may wonder, why worry about it? Because those small amounts of power can add up and they all use power that must be created by an inverter.

This is a device that changes low voltage DC power into 120 volt AC power. A good inverter will run only when an electrical appliance needs power. When no power is needed the inverter should go into "sleep" mode, sending tiny amounts of power through the wires. It will do this until it senses a load and will then turn itself back on, and it does it in milliseconds.

The reason for this has to do with the way an inverter produces AC power. It takes a certain amount of energy to create AC power from DC power (the energy stored in your batteries). Most modern inverters will run at an efficiency of between 85% and 95%. This means that 85 - 95% of the DC power the inverter draws will get turned into AC power. The balance represents the energy used by the inverter.

The efficiency is poorest for very small AC loads. This means that for small energy consumers like clocks and answering machines the inverter uses quite a bit more power from the batteries than it needs to run the device. Also, the whole time the inverter is running it puts a load on the batteries and keeps them from charging to their fullest.

One way to overcome this is to have plenty of charge going to the batteries, either by having an excess of PV panels or an extra large wind generator. In a renewable energy system with a gas generator as backup this can mean having the generator run every other day.

The extra PV or wind generation capacity can be expensive and running a generator that often will mean increased maintenance and fuel costs. Oh yes, and one hard truth about generators, they always break down on a Saturday night in the middle of a blizzard. Better to design your system so the generator runs only once a week at most, or in emergencies.

A cheaper way to combat this problem is to eliminate Phantom Loads from your home. Instead of plug in clocks, buy wind up or battery powered ones. Unplug the answering machine when you are home or buy one that can be converted to run directly on DC power from the batteries. Or better yet, get voice messaging from the phone company (unfortunately, not available everywhere).

You may wonder why I mentioned TVs, VCRs, and stereos because you think you keep them turned off. However, even when "off" you can still see a small glowing light, a clock or other display on your electronic equipment. It takes power to run those displays and even though the device is "off" it still consumes power. Plus, any device that can be turned on by a remote control has to have a receiver in it that responds to the remote control. It takes power to run that receiver.

In fact, electronic devices like these can consume 5 to 8 watts each even when "off", and this can put a considerable drain on a renewable energy system. A home entertainment system's components can consume as much as 30 watts even when off. At 24 hours a day that translates into 720 watt hours (30 x 24) of energy used to do nothing. For a system where the charging source may produce 2500 watthours of power in a day, this amounts to a significant chunk of your available energy.

This doesn't mean you have to give up your home entertainment system. We have all the usual culprits in our home, a TV, VCR, stereo, satellite receiver, CD player and tape deck. But we have our system set up so we can switch off the power to the units when we are not using them.

This means that the inverter only has to run while we are watching or listening and can be idle the rest of the time, thus easing the load on the batteries. This may sound like a lot of trouble but we really don't think about it anymore. Our system is plugged into outlets that are controlled by a wall switch. When we want to watch TV we simply flip on the wall switch and then turn on the TV and when we our done we flip the wall switch off. You can also achieve this same effect with an outlet strip with a switch on it, available at any hardware store.

You may have other kinds of Phantom Loads in your house. As an exercise, put on your renewable energy hat and take a tour of your house. Notice how many "convenience" items you have that run all the time. The clock in your "gas" stove, the clock and timer in the electric coffee maker and remember, not all of them have lights to give them away.

It can be quite revealing to sit in your darkened house at night and realize how many of these green-eyed "phantoms" are staring back at you. It has also been a revelation for us how easy it was to get rid of them without giving up a single "convenience". A lot of advertising dollars have been spent to convince us that something isn't "convenient" unless it plugs into the wall. Yet, almost every electrical "convenience" has a non-electrical equivalent. Sometimes I think these "conveniences" benefit the utility company much more than they benefit us.

In the next article I will give a brief non-technical explanation of how electricity works in a renewable energy home. A slightly different way of looking at volts, amps, watts and watthours than you may have gotten in your high school science classes.

All Contents © 1997
Wagonmaker Press
Thomas W. Elliot


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