Inverter Sizing Calculator Formula
Understand the math behind the inverter sizing calculator. Each variable explained with a worked example.
Formulas Used
Recommended Inverter Size
inverter_size_w = total_panel_watts / dc_ac_ratioInverter Size (kW)
inverter_size_kw = total_panel_watts / dc_ac_ratio / 1000DC Oversize Headroom
clipping_headroom = (dc_ac_ratio - 1) * 100Variables
| Variable | Description | Default |
|---|---|---|
total_panel_watts | Total Panel Wattage (DC)(W) | 8000 |
dc_ac_ratio | DC-to-AC Ratio | 1.2 |
How It Works
Solar Inverter Sizing
The inverter converts DC power from solar panels to AC power for home or grid use. It is typically sized smaller than the total panel capacity.
Formula
Inverter Size (W) = Total Panel Wattage / DC-to-AC Ratio
A DC-to-AC ratio of 1.1-1.3 is standard. This means the inverter is smaller than the panel array. This is efficient because panels rarely produce their full rated power simultaneously. A ratio of 1.2 means 20% overbuilding on the DC side, which captures more energy during low-light hours with minimal clipping losses at peak.
Worked Example
An 8 kW (8,000 W) panel array with a 1.2 DC-to-AC ratio.
- 01Inverter size = 8,000 / 1.2 = 6,667 W
- 02That is a 6.67 kW inverter
- 03DC oversize headroom = (1.2 - 1) x 100 = 20%
Ready to run the numbers?
Open Inverter Sizing Calculator