Wednesday, July 19, 2006

Going solar: electric load

The first step to going solar is figuring out what one's electric load is. A load in this sense is any item that draws power, from a telephone to a lamp to a circular saw to a computer monitor. A local company, ABS Alaskan, has a handy page with forms for determining how much power one uses. I can always look at my electric bill, too, but GVEA doesn't tell me anything other than the total usage. It doesn't let me calculate the electricity draw for all the powered appliances and tools and widgets that I have in my office, nor what my potential peak use could be.

Here's ABS's step-by-step how-to list:
1. List all your electrical appliances.
2. Determine the power draw for each item. This means wattage, and whether it runs on alternating or direct current. (Amperage and voltage can be used to figure the load, too, if wattage isn't listed.)
3. Estimate appliance usage time, in hours per day.
4. Look for extra efficiency, or where the load can be reduced.
5. Determine your AC power needs: find the AC appliance with the highest wattage, then figure out how many AC items will be plugged in at the same time and add that together. (This helps you determine the size inverter you will need.) Also check to see what the start-up power draw is on each AC appliance (some things, like refrigerators, draw way more on start up than they do once they've gotten going). This will help determine the power surge requirements for your electric load, and thus the size of your inverter.
Here's ABS's load calculation form.

3 comments:

John said...

I am so *for* solar, but the technology right now takes a bazillion years to pay for itself. Wood, though, is still cheap.

Deirdre Helfferich said...

Yeah, but wood doesn't do diddly for the electric bill.

Rob said...

Solar power needs to be integrated in any serious energy policy. Tough to do in an urban environment these days but necessity may inspire creativity. Thanks for the guide.