01
Formula
Kilowatts = daily kWh ÷ sun hours ÷ derate.
Panels = kilowatts × 1,000 ÷ panel watts, rounded up. Runtime hours = amp-hours × volts × usable fraction ÷ load watts. Nameplate watt-hours are amp-hours times volts before the usable fraction.
Apply for financingSolar calculator
Solar panel calculator for array size and battery runtime
This solar calculator divides daily kilowatt-hours by the peak sun hours and the derate you enter, then counts panels. The battery mode is a battery run time calculator from amp-hours, voltage, and load.
Size
Array size
7.50kW
Panels to order19
Panels before rounding18.75
Daily energy30.00 kWh
A planning sketch from the sun hours, derate, and loads you enter. It is not a site survey, a production guarantee, or a utility rate.
How it works
Array kilowatts equal daily energy divided by sun and derate.
Daily kilowatt-hours divided by peak sun hours gives the kilowatts you would need if every hour were perfect. Divide again by the derate, which starts at 0.8, to leave room for heat, dust, wiring, and inverter loss. That 0.8 is a planning input, not a site measurement. Panels equal array watts divided by the wattage printed on the panel, rounded up. Sun hours are yours to enter. This solar panel calculator does not know the roof. Battery runtime in hours is amp-hours times volts times the usable fraction, divided by the load in watts. That is the battery capacity calculator view of the same watt-hours.
02
Example
30 kWh a day, 5 sun hours, 0.8 derate, 400 watt panels.
The array is 7.50 kW. That is 18.75 panels before rounding, so order 19. On the battery tab, a 100 Ah 48 volt bank at a 0.9 usable fraction feeding 500 watts runs 8.64 hours. Change the sun hours to match the site. Five is only the filled-in example.
03
Tips
Do not treat the derate as a production promise.
Shade, tilt, and temperature are why the derate is editable. A solar battery calculator that ignores the usable fraction will overstate the night. The fraction starts at 0.9 so you can lower it for the chemistry you actually have.
04
Equipment
The array size is not an equipment approval.
Dengaro finances business equipment from $15,000 to $2 million. Use the button if the purchase is equipment in that range. The kilowatt result is not a utility offer and not a loan amount.
Important questions
Know what to expect.
What does the solar calculator need that a map would usually supply?+
Peak sun hours. Type them. The page does not look up a city, and it does not claim a production total for a roof it has not seen.
How does the battery run time calculator treat capacity?+
Amp-hours times volts is nameplate watt-hours. Multiply by the usable fraction, then divide by the load in watts to get hours. A solar battery calculator mode on this page is that same runtime. It does not model cloudy days or charge current.
Why are panels rounded up?+
You cannot buy a fraction of a panel. The line above the rounded count shows the exact quotient so you can see how close the next panel is.
Is 0.8 a required derate?+
No. It is a starting assumption so the example is reproducible. Replace it with the factor your design uses.
Financing built into the sale