5,647.0588 Wh is the example result. Read it using the units and relationship stated below.
Critical Load Solar uses critical load (w), backup hours, system efficiency (%).
Distinguishing electrical arithmetic from equipment selection
For critical load solar, the relationship is Result = (([Critical load (W)] × [Backup hours]) ÷ ([System efficiency (%)] ÷ 100)). The amount depends on the supplied critical load (w), backup 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 = (([Critical load (W)] × [Backup hours]) ÷ ([System efficiency (%)] ÷ 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
Critical load (W): 800; Backup hours: 6; System efficiency (%): 85. Result: 5,647.0588 Wh. The values are illustrative.
Compare one changed input
Critical load (W) changes from 800 to 880. The result becomes 6,211.7647 Wh. All other inputs remain fixed.
Calculation rule
Result = (([Critical load (W)] × [Backup hours]) ÷ ([System efficiency (%)] ÷ 100))
Inputs and output
| Input | Example value | Entry convention |
|---|---|---|
| Critical load (W) | 800 | Use the source quantity represented by critical load (w). Keep the counted population fixed and avoid mixing a unit value with a period total. |
| Backup hours | 6 | Use the duration unit stated in backup hours. A time period is not interchangeable with a currency amount or a count of events. |
| System efficiency (%) | 85 | Enter system efficiency (%) 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: 5,647.0588 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 Critical load (W), Backup hours, System efficiency (%). 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 Critical 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 5,647.0588 Wh.
Change Critical load (W) from 800 to 880 while keeping every other value fixed. The result becomes 6,211.7647 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