4 is the example result. Read it using the units and relationship stated below.
Solar Panel Number uses daily energy use (wh), panel wattage, peak sun hours.
Distinguishing electrical arithmetic from equipment selection
For solar panel number, the relationship is Result = round up((([Daily energy use (Wh)]) ÷ ([Panel wattage] × [Peak sun hours] × ([System efficiency (%)] ÷ 100)))). The amount depends on the supplied daily energy use (wh), panel wattage, 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 = round up((([Daily energy use (Wh)]) ÷ ([Panel wattage] × [Peak sun 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
Daily energy use (Wh): 5000; Panel wattage: 400; Peak sun hours: 5; System efficiency (%): 80. Result: 4. The values are illustrative.
Compare one changed input
Daily energy use (Wh) changes from 5000 to 5500. The result becomes 4. All other inputs remain fixed.
Calculation rule
Result = round up((([Daily energy use (Wh)]) ÷ ([Panel wattage] × [Peak sun hours] × ([System efficiency (%)] ÷ 100))))
Inputs and output
| Input | Example value | Entry convention |
|---|---|---|
| Daily energy use (Wh) | 5000 | 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. |
| Panel wattage | 400 | Use the source quantity represented by panel wattage. Keep the counted population fixed and avoid mixing a unit value with a period total. |
| Peak sun hours | 5 | Use the duration unit stated in peak sun hours. A time period is not interchangeable with a currency amount or a count of events. |
| System efficiency (%) | 80 | 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: 4 is the example result. Read it using the units and relationship stated below. Use the formula to distinguish a cash amount, count, percentage or ratio.
How to use the page
Collect the inputs
Gather Daily energy use (Wh), Panel wattage, Peak sun hours. 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 Daily energy use (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 4.
Change Daily energy use (Wh) from 5000 to 5500 while keeping every other value fixed. The result becomes 4. 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