Part 1:
Watch the Video. https://www.youtube.com/watch?v=P2XSbDRi6wo
Part 2:
Work out your power needs:
Refer to your electric bill and determine your total power needs. The electric bill should include a Kwh/day or Kwh/month rating. If Kwh/month, convert to kwh/day by dividing by 30. Convert kwh/day amount to watt-hours/day. (You can use this calculator) (Links to an external site.)
Sizing Battery Bank
Load the website Off-grid solar power systems (Links to an external site.)
Scroll to the section in the Off-grid solar power system website titled “Designing/sizing an off-grid solar power system”
Click “step 2. Sizing a battery tank.” This will open a new window with a calculator.
We will use this calculator to generate Amp-hours needed for battery power under 9 different scenarios, listed in the tables below.
Days without Sun scenarios:
Sun #1
Sun #2
Sun #3
Insert Wh/day from part 1
Insert Wh/day from part 1
Insert Wh/day from part 1
Battery Bank Voltage: 12
Battery Bank Voltage: 12
Battery Bank Voltage: 12
Days without Sun: 2
Days without Sun: 3
Days without Sun: 5
Depth of Discharge: 50
Depth of Discharge: 50
Depth of Discharge: 50
Temperature Multiplier: 1.04
Temperature Multiplier: 1.04
Temperature Multiplier: 1.04
Amp-Hours????
Amp-Hours????
Amp-Hours????
Depth of Discharge scenarios (the amount of your battery’s capacity that you use at one time):
DoD #1
DoD #2
DoD #3
Insert Wh/day from part 1
Insert Wh/day from part 1
Insert Wh/day from part 1
Battery Bank Voltage: 12
Battery Bank Voltage: 12
Battery Bank Voltage: 12
Days without Sun: 3
Days without Sun: 3
Days without Sun: 3
Depth of Discharge:20
Depth of Discharge:45
Depth of Discharge:70
Temperature Multiplier:1.04
Temperature Multiplier:1.04
Temperature Multiplier:1.04
Amp-Hours????
Amp-Hours????
Amp-Hours????
Temperature multiplier scenarios:
Temp #1 (70deg F)
Temp #2 (50deg F)
Temp #3 (20deg F)
Insert Wh/day from part 1
Insert Wh/day from part 1
Insert Wh/day from part 1
Battery Bank Voltage: 12
Battery Bank Voltage: 12
Battery Bank Voltage: 12
Days without Sun: 3
Days without Sun: 3
Days without Sun: 3
Depth of Discharge: 50
Depth of Discharge: 50
Depth of Discharge: 50
Temperature Multiplier:1.00
Temperature Multiplier:1.19
Temperature Multiplier:1.59
Amp-Hours????
Amp-Hours????
Amp-Hours????
Part 3: Graphing
To understand what kind of battery power is needed to store energy to power your needs under all the above scenarios, we will use the above data to visualize the differences.
Amp-hours will be on the x-axis of your graph, and the variable you alter will be on the x-axis (days w/o sun, depth of discharge, temp). So, you will need to create 3 separate graphs or 1 graph with each variable clustered together on the x-axis. I would recommend a bar or a scatter plot.
how does the amount of energy stored in the battery, expressed in amp-hours, change depending on the # of days without sun? As the number of days without sun increases, does your battery needs change?
how does amp-hours change depending on the depth of discharge?
how does amp-hours change depending on temperature?
https://www.asknumbers.com/kwh-to-watts-hour.aspx
https://rimstar.org/renewnrg/off_grid_solar_power_systems.htm
