A 100 kWp rooftop array with a target DC:AC ratio of 1.25. Why a 75 kW inverter is typical and a 60 kW inverter would clip heavily.
| PV array | 100 kWp DC at STC |
| Target DC:AC ratio | 1.25 |
| Candidates | 75 kW and 60 kW AC inverters |
A PV array rarely delivers its STC rating because of temperature, soiling, irradiance below 1000 W/m² and DC losses. A moderate DC:AC ratio keeps the inverter near full output for more hours, accepting a little clipping around midday. The acceptable ratio depends on climate and should be confirmed with an energy-yield simulation.
| Check | Requirement | Actual | Status |
|---|---|---|---|
| 75 kW inverter | ILR within 1.15–1.35 | 1.33 | ✓ PASS |
| 60 kW inverter | ILR within 1.15–1.35 | 1.67 | ✗ FAIL |
Key insight: The DC:AC ratio is an economic choice, not a safety limit. Electrically, the inverter's DC input voltage and current limits must still be checked separately.
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Open Inverter Sizing — Solar, Off-Grid & ILR calculator →Hot sites lose more array output to temperature, so ratios at the upper end of the range are common, but yield simulation should confirm the clipping loss.
No. The inverter limits its own output. The risk is lost energy, plus the need to stay within the inverter's maximum DC input current and voltage.