Solar Inverter Sizing Calculator
Size a solar inverter using the DC-to-AC ratio and check for clipping.
Please note: Estimates for planning only. Actual solar output depends on your latitude, roof orientation, shading, weather and equipment. Get a site-specific assessment and quotes before committing.
What the Solar Inverter Sizing Calculator does
Solar arrays are deliberately larger than their inverters. Panels only reach nameplate output in perfect conditions, so a DC/AC ratio of 1.1 to 1.3 lets a cheaper inverter run near full load for more hours, losing only a little to clipping on the brightest days.
Formula
DC/AC ratio = Array kW (DC) ÷ Inverter kW (AC)Inverter size = Array kW ÷ Target ratioRealistic peak = Array kW × Peak output shareClipping = max(0, Realistic peak − Inverter kW)
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Array size (DC) | kW | Yes | Accepts more than 0. |
| Calculate | one of 2 options | Yes | — |
| Target DC/AC ratio | number | In some modes | 1.1–1.3 is typical. Accepts 0.5 or more, up to 2. Shown Calculate is Inverter size from a target ratio. |
| Inverter size (AC) | kW | In some modes | Accepts more than 0. Shown Calculate is Ratio from a chosen inverter. |
| Peak sun hours per day | one of 7 options | Yes | Average daily equivalent hours of full-strength sunlight for your location. |
| System losses | % | Yes | Inverter, wiring, soiling, heat and mismatch losses combined. 20% is typical. |
| Peak array output | % | Yes | Real peak as a share of nameplate — heat and angle mean panels rarely hit 100%. |
How to use it
- Choose Calculate and Peak sun hours per day.
- Enter Array size (DC), System losses and Peak array output.
- Fill in the remaining inputs the form shows for your choice.
- Select Calculate.
Worked example
An 8 kW DC array with a 1.25 target ratio and a realistic peak of 85% of nameplate.
- Array
- 8 kW
- Ratio
- 1.25
- Peak share
- 85
Inverter 6.4 kW AC. Realistic peak 6.8 kW, so 0.4 kW of clipping — about 5.9% at peak only.
Frequently asked questions
Is clipping bad?
Not usually. It only bites for a few hours on the brightest days and typically costs 1–3% of annual output, which is far cheaper than buying a larger inverter.
What DC/AC ratio should I use?
1.1 to 1.3 for most installations. Go higher in cloudier climates where the array rarely approaches nameplate, lower where clear bright conditions are the norm.