To get the spreadsheet, click on the orange
Button in the upper right of this page.
This sheet is intended to help you plan your system. Fill it out down to the last decimal place, look at the results..... and then make your best guess
Note: Be sure to look at the "Sample" tab in the workbook.
For things like refrigerators that turn on and off by themselves, it is handy to put a Kill-a-watt on it and measure the watt-hours consumed over a set period of time. From that it is possible to calculate the daily usage and the time on per day. Here is an example with random numbers:
Measured with Kill-a-watt
Watts used while on: 6W
Watt-hours over a 6 hour period: 18Whr
Calculated:
Average Watt-hours per hour = 18Whr/6hr = 3Whr/hr
Watt-hours per day = 3Whr/hr * 24 Hr/day = 72Whr/day
Time on per day = (72Whr/day)/6W = 12 hrs/day
Note: This resource is a duplicate of the resource of the same name in the 'Planning and Sizing Tools' resource Section. This resource is linked to the same download file.
This sheet is intended to help you plan your system. Fill it out down to the last decimal place, look at the results..... and then make your best guess
Note: Be sure to look at the "Sample" tab in the workbook.
- One of the best uses of the sheet is to help you identify where to reduce/conserve. (Energy not used is the cheapest)
- To get the best sizing, use measured values of wattage for the load calculations. If you use the values shown on the back of the device, it will almost always be higher than actual. The higher-than-actual number then gets fed into the system sizing and the difference can get amplified.
Note: @Brendan Wood posted a resource with 'typical' wattage/power usage for many different appliances. https://diysolarforum.com/resources/lcec-household-wattage-worksheet.57/
If you don't have any other numbers, you can use these to get a 1st approximation of your projected usage. - Figuring out hours of use to put in the spreadsheet:
For things like refrigerators that turn on and off by themselves, it is handy to put a Kill-a-watt on it and measure the watt-hours consumed over a set period of time. From that it is possible to calculate the daily usage and the time on per day. Here is an example with random numbers:
Measured with Kill-a-watt
Watts used while on: 6W
Watt-hours over a 6 hour period: 18Whr
Calculated:
Average Watt-hours per hour = 18Whr/6hr = 3Whr/hr
Watt-hours per day = 3Whr/hr * 24 Hr/day = 72Whr/day
Time on per day = (72Whr/day)/6W = 12 hrs/day
Note: This resource is a duplicate of the resource of the same name in the 'Planning and Sizing Tools' resource Section. This resource is linked to the same download file.
