What My Solor Roof Taught Me: Knowledge Really Does = Power
by Sarah S. Mosko, Ph.D.
I was pretty clueless when I recently installed photovoltaic (solar) panels on the roof of my house. All I knew was that all forms of energy consumption contribute to global warming (not just driving) and that I wanted to be part of the solution. I was nothing short of giddy when the “consumption wheel” on my electricity meter started turning backwards for the first time, veritable proof that I was generating more electricity than I was using. Energy was flowing from my rooftop right onto the grid.
Elation soon gave way to curiosity, however, just like after I had purchased a hybrid Prius and could not help but experiment with ways to maximize my gas mileage. My new passion centered on how to insure an energy surplus on my next electric bill. Switching out the incandescent light bulbs in my house for energy saving compact fluorescent ones was a no brainer. But I also had to get acquainted with my household appliances along a totally new dimension: I needed to know how much energy a given appliance consumes when in use so I could make more informed decisions when contemplating turning it on. Here is what I found out.
Most appliances carry a metal plate that lists the power requirement measured in watts or amps (watts = amps x volts). To figure out how much energy an appliance consumes, just multiply the power times the length of time it is in use. An easy example: one 100 watt light bulb turned on for 10 hours equals 1,000 watt hours (or 1 kilowatt hour, “kWh”). To grasp how much energy a kilowatt hour is, consider this: one gallon of gasoline is equivalent to 35 kWh of energy. One kilowatt hour would propel the average automobile about 0.6 miles at 20 mpg.
The power requirements of my household appliances are listed below, all in the same units (kilowatts, kW) and in increasing order to make comparisons easy. I chose kilowatts because electric companies charge by the kilowatt hour. A 100 watt incandescent light bulb is included to provide a reference point.
Digital clock 0.003 kW
DVD player 0.010 kW
Video cassette recorder 0.020 kW
Answering machine 0.048 kW
19″ Color TV 0.090 kW
100 W light bulb 0.10 kW
19″ Computer monitor 0.32 kW
Computer tower 0.69 kW
Gas clothes dryer 0.72 kW
Clothes washer 0.96 kW
Dishwasher 1.03 kW
Stream iron 1.20 kW
Refrigerator 1.39 kW
Microwave 1.52 kW
Gas house furnace 1.54 kW
Toaster oven 1.55 kW
Hair dryer 1.88 kW
Air conditioning system 4.56 kW
Electric convection oven 5.90 kW
I was more than dismayed to learn that my air conditioner consumed electricity at a rate more than 1,500 times my digital clock and made my electricity meter spin forward at alarming speed. Even my home heating system, which runs mostly on natural gas, ate up electricity 500 times faster than my clock. Your appliances’ power requirements will differ somewhat from mine, and keep in mind that appliances such as air conditioners that automatically turn on and off do use less energy periodically. But the point is that appliances vary greatly in their power usage, and if your goal is to contribute less to global warming you need to be in touch with your personal energy consumption.
I realize that many people may not be in a position today to install solar panels because the initial investment is still pretty high. For example, my out-of-pocket expense after rebates and tax breaks was about $15,000 for a 3 kW system that generates more electricity than my three-person, 3,300 sq. ft. household uses. However, the resale value of my home immediately jumped more than $20,000 and my monthly electricity bill is next to zero (I still have to pay Southern California Edison a monthly service fee that’s less than $2).
Yet, we all make the same decision to consume energy every time we turn on an appliance. Now that I know that heating my home eats up a full kilowatt hour of energy in just 40 minutes, putting on a sweatshirt and booties on a cool winter morning seems less like a hassle than it did before. Even living away from the coast in Orange County, I find that open windows comfortably stave off the summer heat and leave me smiling when my air-conditioned neighbors complain about their exorbitant electricity bills. What’s more, I have decided that my hair really does look OK sometimes if I forego the hair dryer and let it dry naturally.
Strangely enough perhaps, I am squandering less and conserving much more since I’m generating my own electricity. For me, the familiar adage “knowledge is power” has taken on a whole new meaning.