Off-grid solar and battery sizing calculator: the Loads and System Design sheets, with daily energy and required PV array size
  • Off-grid solar and battery sizing calculator: the Loads and System Design sheets, with daily energy and required PV array size
  • Daily load table listing appliances with watts, hours per day, start surge multiplier and energy per day
  • PV array and string check section with module Voc, Vmp and temperature coefficients checked against controller limits
  • Battery bank, charge controller and inverter sizing section with depth of discharge, units in series and parallel, and surge check
  • Cost and payback sheet with local prices per component and a 25-year cumulative cash chart
  • What you get: one Excel file with Start Here, Loads, System Design, Cost & Payback and Lists sheets

Off-Grid Solar + Battery Sizing Calculator

Sizing an off-grid or hybrid solar system starts with one number: how much energy you use each day. This workbook starts there. List up to 40 AC or DC appliances and it adds up daily energy, peak load and motor start surge. From peak sun hours and your losses it sizes the PV array, then checks modules per string against your charge controller or hybrid inverter: cold-weather Voc, hot and cold Vmp inside the MPPT window, and current per tracker. It works out a LiFePO4 or lead-acid battery bank from days of autonomy and depth of discharge, suggests the next standard controller and inverter with a surge check, and adds a 25-year cost and payback view in any currency. Every check line turns green or red and says why. It is a monthly-average energy balance, so check the result against local rules and equipment datasheets.

$5.69 on Etsy

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Scripts recalculated this file in Excel for Mac 16.114.3 and LibreOffice. Excel for Windows, older Excel versions and Google Sheets have not been tried.

Instant download from Etsy · nothing shipped

What's included

  • Off-Grid-Solar-Battery-Sizing-Calculator.xlsx: one Excel file
  • Off-Grid-Solar-Battery-Sizing-Calculator-Example-Printout.pdf: a printable PDF of the example
  • Sheets: Start Here, Loads, System Design, Cost & Payback, Lists (standard sizes you can edit)
  • Worked example: an off-grid cabin on a 48 V LiFePO4 bank
What you get: one Excel file with Start Here, Loads, System Design, Cost & Payback and Lists sheets

How it works

  1. Daily load table listing appliances with watts, hours per day, start surge multiplier and energy per day
    List your daily loads The Loads sheet: enter quantity, watts and hours for each appliance, mark loads that run at the same time and give motors a start surge multiplier.
  2. PV array and string check section with module Voc, Vmp and temperature coefficients checked against controller limits
    Size the PV array and check the string The System Design sheet sizes the array from the energy the PV must deliver, then checks module Voc, Vmp and current against your controller or inverter limits.
  3. Battery bank, charge controller and inverter sizing section with depth of discharge, units in series and parallel, and surge check
    Size the battery, controller and inverter Depth of discharge and autonomy give the battery units in series and parallel; peak load and motor start set the controller and inverter size.
  4. Cost and payback sheet with local prices per component and a 25-year cumulative cash chart
    See cost and simple payback Enter local prices in any currency to get capital cost by component and an undiscounted 25-year cash view against the grid or generator energy it replaces.

Compatibility and file formats

Scripts recalculated this file in Excel for Mac 16.114.3 and LibreOffice. Excel for Windows, older Excel versions and Google Sheets have not been tried.

Instant download from Etsy · nothing shipped.

Video

Questions

Where do I get peak sun hours?

Free tools such as PVGIS (EU JRC) or NASA POWER. Use the worst month for an off-grid system.

Grid-tied systems?

It is built for off-grid and hybrid (battery) systems. For grid-tied without batteries, the PV and string parts still apply.

Lead-acid?

Yes. Set depth of discharge (e.g. 0.5) and round-trip efficiency (e.g. 0.85).

Estimation aid. Check against your local code and equipment datasheets.

Related

Also included in this bundle:

Guide: How to size an off-grid solar system: panels, battery and inverter