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The Energy Efficient Holiday Light Spectacular: Power
As it turns out, the display came nowhere near that upper ceiling on the amount of power
that it could consume. And all the lights are plugged in through a single electrical outlet.
Thanks to LED technology, the lighting for this display uses far less power than even a very modest Christmas display.
Computer control reduces the power even further because the entire display isn't all lit at the same time. Finally,
the micro-power FM transmitter reduced the need to large outdoor speakers, because people can hear high
quality music in their own car.
The very same components that help reduce the energy requirements of the display (LEDs, computer control, FM transmitter) also serve a dual purpose in making the display snazzier. The LEDs give intense colored lighting (like very rich blues). The computer control makes for eye catching performances. And the FM transmitter makes for high quality music reproduction from the warmth of the inside of a vehicle.
So how much power does it all use? But because the lights are always changing, you can't just take a measurement at one
point in time to find out how much power the display is using. You have to average it over a period of time.
Here are the most meaningful measurements for the display:
Standby - 6 watts (0.05 amps) with the microcontrollers active but all lights off
The Dell PC inside the house that drives the display also uses a relatively significant amount of power. It is currently estimated to take 100 watts (~1 amp) of power.
The entire system uses 4.61KWH of electricity per day. The electric company currently charges $0.08 per kilowatt hour. So that is $0.3688 per day. Over a month, the electricity would add up
to $11.04 in extra costs.
In an average December, my home uses about 2000Kwh of electricity. Adding the extra 138 kilowatts (4.61kwh * 30 days) for the display will end up increasing my household power consumption by 7%.
I learned an important energy saving tip from my Kill-A-Watt: a refrigerator will consume less electricity, and will work better, when you clean the dust from its coils on a regular basis.
In this case, instead of spending 100 watts or more on speakers, we're consuming almost no power by transmitting an FM
signal. But that isn't the whole story. While we're not consuming any power on our end, we've just shifted the burden to someone else.
A car's radio is powered by an alternator, which is tied to the engine of a vehicle. And the engine of a vehicle is powered by gasoline. By saving ourselves electricity, aren't we just making others burn fuel? They could have gotten out of their car, or rolled down the window to listen to the music.
Yes and no. And like every energy choice, there is ample room for spin. Technically, it is true that these people are
paying (in gasoline) to listen to the radio. But at the same time, they're receiving an additional benefit that wasn't
there before. They are inside, and warm, rather than being outside and listening to the music in the cold.
So, yes, they're paying for their music in gasoline. But at the same time, they're getting better quality music, and
they're staying warm. Both of which makes for a better presentation. Although, arguably, it isn't as energy efficient as making people get out of their cars and listen to some outdoor speakers. But it does make the viewer more comfortable, and
makes the music easier to listen to.
The initial investment in equipment costs a
great deal of money. Many times, the money that you would have used to buy a larger power generating system is
better spent in reducing the power that you are currently consuming. It is cheaper to buy energy efficient
appliances that require less energy than it is to buy a larger power generation system to handle an inefficient
appliance.
So for the display, the first thing to do would be to save 95 watts of power by replacing
the Dell PC with the recently released MP3 Show Director (a stand-alone board that controls
all the lights and the music, in place of a general purpose PC). That would reduce the total
power requirements of the display from 300 watts down to 205 watts of power. (Cost: $250.)
A power solution that is two thirds as big (and potentially less expensive) could then be
used to run the display. (Savings: thousands of dollars.)
Next would be do purchase some sort of alternative power system. A backup generator that ties into the natural gas line?
It would get you off the grid, but it wouldn't make environmental or economic sense here, since the area's power plant
is already natural gas powered. Might be nice for when a tree limb snaps and takes a power line out, though.
Wind turbine powered? Aside from being an eyesore, and causing potential zoning or covenance issues, these tend to make enough noise that they aren't at all suited for a small city lot. This could work well in a large country lot that has a fair amount of wind.
Solar panels on the roof that charge batteries during the day? A small system would work in this part of the
country just fine. The panels would charge the batteries during the day, and the lights pull power from the batteries
at night.
Doing some research, I found a number of kits that would likely do the trick. Prices ranged from $3,000 to $6,000 for a suitably sized stand-alone system that did not tie into the power
grid. This 376 watt cabin kit generates more power in the winter
(at the local equivalent of 4.2 full sun hours available in winter) than a 175 watt light display will consume in 9 hours. Its batteries have enough capacity to run the display for up
to two cloudy days without any sunlight. It costs $3,500, plus tax, shipping, and installation.
That's quite a lot of money to be spending to say that you've got a solar powered Christmas light display that is off the grid. In fact, it just doesn't really make much sense in order to save $11 in electricity over Christmas, and up to $132 over the course of a year.
If you want your next Christmas to be green on energy, focus on reducing your power consumption. Buying LED lights is a
great way to do just that. If you want to save even more electricity with a computer controlled Christmas, a dedicated Show Director card is
the next logical step. Remember the energy saving bonus of going to a computer controlled display: it uses less power than a regular display, because rarely will all of the lights will be on at the same time.
An energy saving holiday display doesn't have to look cheap!
Then again, you might have another reason for going off the grid. A cabin in the middle of nowhere? A float in a parade?
A boat in a harbor? A nativity scene along the side of the road? Then some of these solutions can actually make a great
deal of sense, if you've got the money to spend on it.
If you are producing your own power, you need to make sure you have a high quality inverter (the device that converts battery voltage to wall outlet voltage) or generator that produces a pure sine wave at 60hz. Typically you won't find a high quality inverter at local retail outlets. If the inverter doesn't a produce a good clean wave (a "modified sine wave" is still quite crude), you will still be able to turn your lights off and on with a computer, but the TRIAC may not be able to fade or dim them correctly.
True sine wave inverters cost more than regular power inverters, and typically are never sold at major retail outlets.
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