Engineering Math P2 Reference 3 min read Reviewed June 4, 2026 Keyur Rakholiya Keyur Rakholiya

Inverter Loading Ratio

Inverter Loading Ratio (ILR) is the ratio of DC array capacity to inverter AC capacity. Equivalent to DC/AC ratio.

Definition

Inverter Loading Ratio (ILR) is the ratio of installed DC array capacity (kW_DC) to inverter AC capacity (kW_AC). Equivalent term to AC/DC Ratio or DC:AC ratio. Typical 1.10–1.40 depending on site and inverter.

Key Takeaways

  • ILR = kW_DC / kW_AC.
  • Synonymous with AC/DC ratio.
  • Typical 1.10–1.40 depending on site.
  • See AC/DC Ratio for full design treatment.

Frequently Asked Questions

2 commonly searched questions about Inverter Loading Ratio.

What is ILR?
Inverter Loading Ratio = kW_DC / kW_AC. Same as DC:AC ratio. Typical 1.10–1.40.
Why is ILR > 1?
Modules rarely produce STC nameplate in real conditions. Oversizing DC captures more morning/evening energy at minimal midday clipping cost.

Need engineering-backed solar designs?

Heaven Designs delivers PE-stamped solar design packages, structural calculations, electrical engineering, and utility-compliant permit plans.