User Manual

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3.3 Power and Energy Requirements
Energy (Wh) is calculated by multiplying the amount of power (W) used for a given amount of time
(hours). This applies to both charging and discharging the battery.
Example:
A typical coffee pot draws 1000 W of power when in use. If the pot is on for 30 min (0.5 hours) the
amount of energy used would equal 500 Wh:
Coffee Pot Power (W) × Time in use (hours) = Total Energy (Wh)
1000 W × 0.5 hours = 500 Wh
Table 2. Power requirements for common appliances
Appliance Watts Appliance Watts
Fluorescent lamp 10 Blender 400
Computer 200-300 Toaster 1000
Microwave (full size) 1500 Washer/Dryer 375-1000
Stereo 50 3/8” Drill 500
Hair Dryer or Iron 1000 Vacuum Cleaner 1200
Refrigerator (3 cu ft) 180 Refrigerator (12 cu ft) 480
Coffee Maker 1000 Ceiling fan 50
3.4 Calculating Battery Bank Size
Table 3. Example worksheet for calculating daily energy requirements
Load Watts Hours Per Day Days Per Week Weekly Watt Hours
10 15W lights 150 6 7 6300
Coffee maker 1200 0.75 7 6300
Laptop 50 5 7 1750
Total Weekly Watt-hours of AC load 14350 Wh
Divided by Days per Week ÷ 7
Average total watt-hours per day 2050 Wh
Table 4. Example calculations for required battery bank size
Average total watt-hours per day 2,050
Account for inverter efciency (90%) 2,050 x 1.11 2,276
Account for battery efciency (95%) 2,276 x 1.05 2,389
Account for battery DOD target (80%) 2,389 x 1.25 2,986
Total adjusted Wh required 2,986
Multiplied by days of autonomy
2,986 x 5 14,930
Total installed energy required 14,930 Wh
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