Solar Electricity
Solar Inverter Size Calculator
Use Solar Inverter Size when suggested inverter rating is the quantity you need. Enter array DC rating and DC-to-AC ratio, then compare the answer with the equipment or operating limits that apply to your case.
Inputs for this calculation
Do not mix values recorded under different conditions.
Compare two operating cases
Change Array DC rating from 7.2 kW to 8.64 kW without altering the remaining fields. The calculated value shifts from 6.00 kW to 7.20 kW.
Do not average the two cases if either could define an operating limit.
Formula used on this page
The arithmetic is based on inverter kW = array kW ÷ DC:AC ratio. The entered quantities are Array DC rating and DC-to-AC ratio.
Using the loaded examples gives 6.00 kW. Your saved case should identify where each entry came from.
Calculate suggested inverter rating from array DC rating and DC-to-AC ratio. For required array size, use Off-Grid Solar Array Calculator.
Input notes
Base energy estimates on the limiting season rather than an annual average alone. Nameplate and meter values are not interchangeable unless they describe the same condition.
Values used below a division bar must stay positive. Convert units once, retain the original reading, and verify the converted magnitude. The next worksheet may be Autotransformer Rating Calculator if autotransformer winding rating is needed.
- Array DC rating
- Default example: 7.2 kW. Enter array DC rating in kW.
- DC-to-AC ratio
- Default example: 1.2. Enter DC-to-AC ratio.
How to use the result
Interpret Suggested inverter rating on the same basis used for the source values. Compare it with cold-voltage, hot-voltage, current, energy-yield, and controller limits.
Label alternate cases rather than overwriting the baseline. For the companion total modules calculation, open Solar Array Configuration Calculator.
Using the answer downstream
Record array DC rating and DC-to-AC ratio with suggested inverter rating. Include the operating state and data source.
Pass suggested inverter rating with all available digits during downstream arithmetic. Round at the final reporting step.
Assumptions and limitations
Clipping and local interconnection limits need separate review.
Depending on the application, account for temperature effects, shading patterns, wiring loss, and equipment availability. Do not hide omitted behavior inside an unexplained correction factor.
Use site-specific irradiance, temperature, shading, and equipment data. When that related quantity matters, continue with Solar Charge Controller Calculator.
Questions from practical use
Why is zero rejected for one of the fields?
A zero denominator is undefined, so the affected field has a positive minimum.
Should I use measured or nameplate values?
Measured and rated values can represent different states. Base energy estimates on the limiting season rather than an annual average alone.
Where is this suggested inverter rating estimate simplified?
Clipping and local interconnection limits need separate review. Also consider temperature effects, shading patterns, wiring loss, and equipment availability.
What explains a gap between calculated and observed suggested inverter rating?
First confirm that the measurements match the equation. Then review temperature effects, shading patterns, wiring loss, and equipment availability.