Load Sizing Worksheet
List all of the electrical appliances that would be powered by your PV system. Separate DC and AC devices and enter them in the appropriate table. Record the operating wattage of each item. Most appliances have a label on the back that lists the wattage. Local appliance dealers and the product manufacturers are other sources of this information. Specify the number of hours per week each item will be used. Use the form below to determine the total watt-hours per week each appliances will require.
Watts = Volts X Amps Amps = Watts divided by Volts
Description of AC Appliance
Determine your AC loads
Watts
X
X
X
X
X
X
X
X
=
=
=
=
=
=
=
=
Hrs/Week
Watt/Hrs/week
Watt Hrs week Total
Total the numbers in the last column. This is your AC power requirement.
Multiply the total by 1.2 to compensate for system losses during battery charge/discharge cycle.
Description of DC Appliance
Watts
X
X
X
X
X
X
X
X
=
=
=
=
=
=
=
=
Hrs/Week
Watt/Hrs/week
Watt Hrs week Total
Total the numbers in the last column. This is your DC power requirement.
Multiply the total by 1.2 to compensate for system losses during battery charge/discharge cycle.
Determine your DC loads
Calculate your average amp-hours per day requirement
1. Add DC loads (DC WH/WK) and AC loads (AC WH/WK) together.
2. Enter the voltage of your battery bank (usually 12 or 24 volts).
3. Divide line 1 by line 2. This is your amp-hour requirement per week.
- Divide line 3 by 7 days. This is your average amp-hour requirement per day that will be used
to size your battery bank and your solar panel array.
Total
Volts
Amp/Hrs/week
Amp/Hrs/Day
