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.)
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.
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.
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.
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.
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.
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.
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).
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.