Solar Inverter Size Calculator
Estimate a preliminary solar inverter AC rating from array power, target DC-to-AC ratio, continuous load, surge load and growth allowance.
Default project preview
9.17 kW AC
Array-driven AC rating
8.33 kW
Load-driven AC rating
7 kW
Estimated surge capability
13.75 kW
Nominal efficient AC output
8.8 kW
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Solar array DC rating
Enter this project assumption in kW DC. The current imperial default is 10 kW DC.
Target DC-to-AC ratio
Enter this project assumption in a unitless value. The current imperial default is 1.2.
Maximum continuous load
Enter this project assumption in kW. The current imperial default is 7 kW. Minimum: 0.
Peak surge load
Enter this project assumption in kW. The current imperial default is 11 kW. Minimum: 0.
Future growth allowance
Enter this project assumption in %. The current imperial default is 10 %. Minimum: 0. Maximum: 50.
Inverter surge multiplier
Enter this project assumption in × continuous rating. The current imperial default is 1.5 × continuous rating.
Expected inverter efficiency
Enter this project assumption in %. The current imperial default is 96 %. Minimum: 1. Maximum: 100.
Budget price per kW AC
Enter this project assumption in a unitless value. The current imperial default is 280. Minimum: 0.
How to read the outputs
Array-driven AC rating
target ratio 1.2. Default preview: 8.33 kW.
Load-driven AC rating
entered continuous load. Default preview: 7 kW.
Estimated surge capability
1.5× multiplier. Default preview: 13.75 kW.
Nominal efficient AC output
96% efficiency. Default preview: 8.8 kW.
Array power above AC rating
potential clipping headroom. Default preview: 0.83 kW.
Planning budget
entered cost per kW AC. Default preview: $2,566.67.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Array-driven rating = DC array power ÷ target DC/AC ratio. The calculator compares that value with continuous load, adds growth allowance and checks the entered surge multiplier.
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Solar Inverter Size Calculator questions
Why can the inverter be smaller than the solar array?+
Solar arrays rarely operate at nameplate power continuously, so many systems use a DC array rating larger than the inverter AC rating.
Is surge power the same as continuous power?+
No. Motors and pumps may need brief starting power above their running load, and inverter surge duration varies by model.
Does this select string voltage or battery voltage?+
No. Voltage compatibility and string design require equipment-specific electrical calculations.