Xantrex Technology 120 VAC/60 Battery Bank Sizing, Example, Page 102, 5,139, 15,417, 30,834

TECHNICAL INFORMATION

BATTERY BANK SIZING

EXAMPLE

Complete the steps that follow to calculate your inverter’s battery bank capacity. No two installations will require exactly the same battery bank capacity. The following example provides a guide for determining your needs. Read through the example and then complete the worksheet on the following page.

STEP 1-4:Determine your Average Daily Watt-Hours Needed.

AC APPLIANCE

Microwave

Lights (x4)

Hair Dryer

Television

Washer

Refrigerator*

Vacuum cleaner

STEP 1

APPLIANCE RUNNING

WATTS

600

40

750

100

375

480/3 = 160

1200

STEP 2

(X)HOURS USED EACH DAY

0.5

6

0.25

4

1

24

1

STEP 3

(X)DAYS USED EACH WEEK

7

7

3

7

2

7

1

STEP 4

(⎟ 7 = ) AVERAGE DAILY

WATT-HOURS NEEDED

300

240

81

400

107

3840

171

STEP 1: Determine what appliances the inverter will power and enter the Appliance Running Wattage of each appliance.

*- Refrigerators and icemakers typically only run about 1/3 of the time, therefore the running wattage is 1/3 of the total wattage of the appliance.

STEP 2: Determine the number of hours (or fractions of hours) you will use the appliance each day;

STEP 3: Multiply the number of days you will use the appliance during the week; this is your Weekly Watt Hours Needed;

STEP 4: Divide your Weekly Watt Hours Needed by 7 to obtain the Average Daily Watt Hours Needed;

STEP 5: Total Average Daily Watt Hours Needed to determine your Total Daily Watt Hours Needed.

Total Daily Watt Hours Needed

5,139

STEP 6: Multiply your Total Daily Watt Hours Needed (Step 5) by the number of anticipated days of autonomy (days between charging, usually 1 to 5) to determine your Autonomy Battery Size (example used 3 days).

STEP 7: Multiply your Autonomy Battery Size (Step 6) x 2 to allow for a 50% maximum battery discharge in normal operation and an additional 50% for emergency situations to obtain your Rough Battery Size in watt-hours.

Autonomy Battery Size

(Watt Hours)

15,417

Rough Battery Size (Watt Hours)

30,834

STEP 8: Multiply your Rough Battery Estimate x 1.2 to allow for an efficiency of 80%. This number is your Safe Battery Size in watt-hours.

STEP 9: Convert your Safe Battery Size to amp-hours. Divide Safe Battery Size by the DC system voltage (i.e., 12, 24 or 48 VDC; example used 24- volts). This number is your Safe Battery Size in amp-hours, which is the battery bank capacity needed before recharging.

Safe Battery Size (Watt Hours)

37,001

Safe Battery Size (Amp Hours)

1,542

Page

102

 2001 Xantrex Technology, Inc.	Telephone: 360/435-8826	SW Series Inverter/Charger
5916 - 195th Street N. E.	Fax: 360/435-2229	Part No. 2031-5
Arlington, WA 98223	www.traceengineering.com	Rev. C: February 2001