2.5 days is the example result. Read it using the units and relationship stated below.
Solar Battery Autonomy uses usable battery capacity (wh), daily energy use (wh).
Distinguishing electrical arithmetic from equipment selection
For solar battery autonomy, the relationship is Result = (([Usable battery capacity (Wh)]) ÷ ([Daily energy use (Wh)])). The amount depends on the supplied usable battery capacity (wh), daily energy use (wh), rather than a live market price or a value imported from another record. Power, energy, voltage and current describe different quantities. Watts represent a rate; watt-hours represent energy over time. Battery and inverter losses can reduce usable runtime even when the rated capacity is unchanged.
What the model includes
Result = (([Usable battery capacity (Wh)]) ÷ ([Daily energy use (Wh)])) Read unit labels before comparing results. Motor estimates depend on phase, efficiency and power factor; energy budgets depend on duration and duty cycle. Nameplate values and measured consumption may differ under real loads. Treat the output as the stated estimate. It does not select a code-compliant conductor, protective device or complete installation. Equipment specifications and applicable requirements remain part of the design decision.
Example with the supplied inputs
Usable battery capacity (Wh): 2000; Daily energy use (Wh): 800. Result: 2.5 days. The values are illustrative.
Compare one changed input
Usable battery capacity (Wh) changes from 2000 to 2200. The result becomes 2.75 days. All other inputs remain fixed.
Calculation rule
Result = (([Usable battery capacity (Wh)]) ÷ ([Daily energy use (Wh)]))
Inputs and output
| Input | Example value | Entry convention |
|---|---|---|
| Usable battery capacity (Wh) | 2000 | Measure usable battery capacity (wh) in the displayed unit. Convert the source measurement before entry if it uses another system; a changed label does not perform a unit conversion. |
| Daily energy use (Wh) | 800 | Measure daily energy use (wh) in the displayed unit. Convert the source measurement before entry if it uses another system; a changed label does not perform a unit conversion. |
Output: 2.5 days is the example result. Read it using the units and relationship stated below. Unit: days.
How to use the page
Collect the inputs
Gather Usable battery capacity (Wh), Daily energy use (Wh). Use one period and the units shown in the form.
Run the calculation
Enter the values and select the action. The calculation rule above explains how the inputs produce the result.
Compare a scenario
Change Usable battery capacity (Wh) on its own, keeping the other inputs fixed. Read both results before changing another assumption.
Worked example
With the example inputs listed above, the result is 2.5 days.
Change Usable battery capacity (Wh) from 2000 to 2200 while keeping every other value fixed. The result becomes 2.75 days. This comparison isolates that input; it does not forecast how other variables will respond.
Check the stated formula, units and limits before using the result in a decision.
Keep the displayed formula, input units and model scope with the result. Corrections or questions can be sent through the request section on this page.
Content updated: October 11, 2026