1,411.7647 Wh is the example result. Read it using the units and relationship stated below.
Power Station Battery Size uses average load (w), runtime target (hours), reserve (%).
Distinguishing electrical arithmetic from equipment selection
For power station battery size, the relationship is Result = [Average load (W)] × [Runtime target (hours)] ÷ (maximum(.01, 1 − [Reserve (%)] ÷ 100)). The amount depends on the supplied average load (w), runtime target (hours), 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 = [Average load (W)] × [Runtime target (hours)] ÷ (maximum(.01, 1 − [Reserve (%)] ÷ 100)) 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
Average load (W): 150; Runtime target (hours): 8; Reserve (%): 15. Result: 1,411.7647 Wh. The values are illustrative.
Compare one changed input
Average load (W) changes from 150 to 165. The result becomes 1,552.9412 Wh. All other inputs remain fixed.
Calculation rule
Result = [Average load (W)] × [Runtime target (hours)] ÷ (maximum(.01, 1 − [Reserve (%)] ÷ 100))
Inputs and output
| Input | Example value | Entry convention |
|---|---|---|
| Average load (W) | 150 | Use the source quantity represented by average load (w). Keep the counted population fixed and avoid mixing a unit value with a period total. |
| Runtime target (hours) | 8 | Use the duration unit stated in runtime target (hours). A time period is not interchangeable with a currency amount or a count of events. |
| Reserve (%) | 15 | Enter reserve (%) on the percentage scale used in the formula (20 means 20%, not 0.20). Keep its base and reporting period consistent with the other inputs. |
Output: 1,411.7647 Wh is the example result. Read it using the units and relationship stated below. Unit: Wh.
How to use the page
Collect the inputs
Gather Average load (W), Runtime target (hours), Reserve (%). 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 Average load (W) 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 1,411.7647 Wh.
Change Average load (W) from 150 to 165 while keeping every other value fixed. The result becomes 1,552.9412 Wh. 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