EV Solar Products
2655 N. Highway 89
Chino Valley, AZ 86323
ph:928-636-2201   fax: 928-636-2015
e-mail: info@evsolar.com


System Sizing Worksheet

The first step to sizing your solar electric system is to determine your average daily power consumption (expressed in watt hours per day). By using the following worksheet you can keep track of each appliance and light you use, and the amount of time you use it. Remember, be as accurate as possible, and consider ways you can conserve power. The number you arrive at will determine the size system you will need. If you have any difficulties with this worksheet, or want some design assistance, please send us your worksheet. We will contact you as soon as we recieve your worksheet and contact information.

1. Choose the appliances you use in the spaces provided. If you use one that is not listed, enter it in the spaces provided.

2. In the second column enter the watt usage of each appliance. Most appliances have a power tag on the back with this information, if there isn't one, use the estimates provided on our power usage chart. A useful formula for this step is: Amps x Volts = Watts.

3. In the third column write the number of hours per week that each appliance and light will be used. For lights, add up the number of hours each type of bulb is on. For example, if you have two 60W bulbs on 3 hours each day, write down 42 hours. Remember that some appliances are only used for a few minutes at a time, such as garage door openers or microwaves. Also, keep in mind that some appliances will be used more or less according to the season (ex: fans). Generally, we size a system according to winter usage, as during the summer months increased power usage is usually offset by an increase in the number of peak sunlight hours. This means you should only include either your heating source OR your cooling source in your calculation, as it is unusual to have both heating and cooling running at the same time.

4. Multiply the wattage of the appliance times the hour per week it is used. This gives you the total amount of power that particular appliance uses.
Daily Watt Hours Calculator

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1) Total Watt Hours / Week
2) Divide line 1 by 7 days. This is your average watt hours per day.
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Note: A standard energy efficient refrigerator will use between 1500 and 1700 watt hours per day. This comes out to between 10500 and 11900 watt hours per week. It is better to enter one of these numbers than to try to figure out how many hours a day your refrigerator is running.

Send Us Your Worksheet!
If you would like help designing your system, please print the form and mail or fax it to us.
As soon as we recieve your worksheet we will take a look at it and contact you.


How Much Will It Cost?
To get an idea of what your system will cost click on the watt hours/day range that is closest to your number. Remember, these are only suggested systems. We can custom design any size system. Please send us your completed worksheet if you would like us to help you design a system that fits your particular needs.

1000 watt hours/day
1001-1500 watt hours/day
1501-2000 watt hours/day
2001-2500 watt hours/day
2501-3000 watt hours/day
3001-3500 watt hours/day
3501-4000 watt hours/day
4501-5001 watt hours/day
5001-5500 watt hours/day
5501-6000 watt hours/day
6001-6500 watt hours/day
6501-7000 watt hours/day

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Updated April 22, 2008