Sizing Solar Power Systems (Simple Spreadsheet)

JamesDowJamesDow Member Posts: 556

For my own amusement, I put together a simple spreadsheet which can calculate estimated battery, solar panel and solar controller needs based off of usage load in watts.
This is a very simple approach to calculating needs.
The spreadsheet is just a rough starting point to view potential solar power requirements. The file also includes a tab/sheet of instructions. (Below is a screenshot of the excel file)
The file is an example of why my solar system (100Ah lithium battery and 100-watt solar suitcase) can't keep up over time (5 plus days) running my refrigerator (47-watts) and other draws such as Fan-Tastic Vent fan (26-watts) during extended time boondock camping. (I really need more solar panels for a 100Ah battery)
Note: If powering 120-volt items such as air conditioning or microwave, one may also need to factor in the power consumption of an inverter and potentially the [email protected] converter.
I am not an expert, the spreadsheet may contain typing, formula or logic errors.
» Please let me know if you find any.
I have included two spreadsheets. One for estimating solar power system needs and the other is a listing of measured power draws of my [email protected]
   Comments Welcome  



Excel Files:
Size Lithium Solar Power System
Trailer Power Usage Log



  • JamesDowJamesDow Member Posts: 556
    edited January 10

    I may want to add some solar panels in parallel to my setup. While a number of calculators are available online, I decided to update my spreadsheet so I could play around with a number of factors.
    This is a simple basic Excel spreadsheet (Easy to use)
    This new update allows one to calculate the power output of adding additional panels in parallel or serial to a setup.
    I currently have two different solar panels with an additional one on the way.
    The spreadsheet allows for efficiency factors for my panels and allows a quick assessment of how things change adding a new panel and/or what happens if just one panel gets shaded, etc.
    » You will need to download the attached Excel spreadsheet to use.
    While cells are protected, the spreadsheet is not password protected.
    A tab with complete instructions is included. (Start reading those first)
    »» Comments are always appreciated. Thanks!

  • ssimonsonssimonson Member Posts: 17

    Thank you for putting in the work and sharing!

  • evpeelingevpeeling Member Posts: 65

    I think we may be kindred spirits. I get way too much enjoyment from making various calculators, complex spreadsheets, and models in excel. Thank you for making this and sharing your work. It's awesome!

    2020 Tag BD 5W, 2018 RAV4 Adventure, PA

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