Lifestyles &
Appliances
Solar Sizer

Lighting

Lighting Guide

Fluorescent lights are the most efficient, halogens use twice the energy for the same amount of light, and regular incandescent bulbs use four times more power than fluorescents. Artists prefer halogens for sharp color, workers prefer fluorescents for less shading. More important than using energy-efficient lighting is turning off lighting that isn't needed.

If your computer won't open the Flash version of the Solar Sizer, you'll have to do this the pen and paper way: for each table, pick the category that best describes your needs and write down the watt-hours. (If your computer will support Flash, click on the Solar Sizer tab above.)

Usage
Watt-hours
2 fluorescents on at a time (avg.)
240
4 fluorescents on at a time
480
6 fluorescents or halogens on at a time
1250
20 halogens or incandescents on at a time
6,000

 

 

 

 

 


Heating & Cooling

Solar Heating & Cooling Guide

Passive solar heating, with large insulated windows facing south, can pay for itself in months not years. Wood stoves and propane wall heaters are good for backup (they don't use electricity). Forced air and radiant floor systems (that aren't designed with electrical efficiency in mind) can consume much of your precious energy, when you need it the most: the dead of winter. We can assist with designing high efficiency radiant floor pumping systems that work on solar.

Air conditioning is NOT practical, except for super efficient evaporative cooling designs which only work well in areas with low humidity (below 40%). Fans are OK, as long as they're not left on continuously. Ceiling fans aren't recommended, simply because they are almost always left on continuously.

Usage
Watt-hours
Passive solar heated + woodstove
0
Simple radiant floor heat, one DC pump
250
Regular zoned floor heat, AC pumps
1250
Forced air blower system
6,000

 

Water Pumping

Water Pumping Tech Guide

Water pumping is your most important power use. Water system energy requirements can range from low to high. On the low end is a rain catchment cistern with a small DC pump. But if your well is deep (over 200 ft), if you are irrigating a garden, or if you have a large family that uses a lot of water for bathing, washing clothes, etc., you will use as lot of energy. The average American uses close to 100 gallons/day per person. Some solar enthusiasts use less than 5 gallons/day.

Usage
Watt-hours
DC pump from cistern
100
DC pump in well (under 200 ft deep)
500
AC deep well pump (to 400 ft) or garden irrigation
1000
Very deep well and/or irrigation system
5,000

 

Refrigeration

Refrigerator Tech Guide

Propane refrigerators don't use precious electricity, but do use fuel. There are both AC and DC electric friges. AC friges are less expensive, and Energy Star models can be very efficient.

Usage
Watt-hours
Propane Fridge
0
Small Sunfrost (DC), or modified Danby (AC)
500
Energy Star 18 cu ft Kenmore (AC)
1000
22 cu ft Fridge & Deep Freeze 10 cu ft. (AC)
3,000

 

Kitchen Appliances

Most kitchen appliances, like microwaves, blenders, and pop-up style toasters, work fine on solar power. Even though they can use a lot of power, they usually are only on for a few minutes each day so the total energy they consume is low (that is, unless you live on toast). Crock pots, toaster ovens, coffee makers with a warmer plate, etc. are not recommended because they may stay on for hours. Use a coffee maker with an insulated carafe, it only takes power for 5 minutes when it's making coffee, then it's off.

Usage
Watt-hours
Good-old hand operated (anything)
0
Microwave, coffee grinder, 2 slice toaster, blender, coffee maker (no warmer)
350
Above + dishwasher, garbage disposal
1250
Above + even more: coffee maker w/ warmer, bread maker, toaster oven
3,000

 

Household Appliances

As before, appliances that stay on for long periods of time (like an electric blanket) are much more of a problem than things that are on for short periods (a hair dryer). Some new appliances like washing machines have computer controls that are not always compatible with mod-sine inverter or generator power.

Usage
Watt-hours
Hand operated (anything)
0
Hair dryer, old washer 2 loads/week
600
Washing machine & gas dryer several loads/week
1250
Above + pool or hot tub, towel warmer, electric blanket, etc.
5,000



Electronics

Electronics on Solar Guide

Most stereos, computers, and TVs work well on solar power. Unfortunately most also have what is known as "Phantom Loads," that is, they consume power even when turned off. This is to power their remote controls or built in clocks, etc. The solution is to unplug these devices when not in use or plug them into a switchable power strip. These phantom loads, while very small (under 20 watts), keep the inverter on 24/7, and can take several solar panels worth of energy production. Portable devices like jamboxes and laptop computers usually use much less power (and space) than desktop models. For example: a desktop computer uses as much energy in one hour as a laptop uses in 5 hours or more.

Usage
Watt-hours
small CD player, radio
100
13" TV for couple of hrs, VCR, laptop computer
250
19" TV, satellite, desktop computer for couple of hrs/day
900
Big screen TV & desktop computer, both for several hrs/day
3,000


Power Tools

Most power tools work fine on solar power. If the inverter is large enough to initially start the motor, it should continue to work. Most tools are really on for just a few minutes at a time, so even though they take a lot of power, it doesn't add up to very much total energy. Air compressors can take a huge amount of electricity to start, so even though their total energy consumption may not be huge, you may need a large inverter to actually run one. Big tools require big inverters.

Usage
Watt-hours
Sander, drill, or jigsaw
240
Circular saw, hammer drill
480
Air compressor, table saw, cement mixer
1250
The above + arc welder, full time shop
12,000

 

The Bottom Line

Add up your watt-hour choices from each section to get your Total Watt-hours per day. This number may be as low as 1000 watt-hrs (1 kWh) or it may be as high as 20,000 watt-hrs (20 kWh).
If it is high you need to start changing your planned lifestyle, because that lifestyle could cost you a fortune.
Check out the Package systems
to get an idea what price range you fall in.

For a more accurate load analysis, print out our Solar Sizer Basic (PDF)

For the technically minded that are ready, you can download our Solar Sizer Excel Spreadsheet.