Inverter Sizing Calculator
Size your solar inverter based on panel array wattage and continuous load
How to Use This Calculator
- Enter your total solar panel array wattage in watts (e.g., 12 × 500W panels = 6000W).
- Enter the maximum continuous AC load you expect to run at once.
- Set the DC-to-AC ratio — 1.2 is typical (inverter rated ~83% of array wattage) to balance clipping and efficiency.
- Choose a motor surge allowance if you run inductive loads (AC, pumps, compressors).
- Read the recommended inverter continuous rating, surge capacity, and suggested battery voltage.
Inverter Sizing Formula
Max AC Output = Panel Array Wattage ÷ DC-to-AC Ratio
Recommended Continuous Rating = Max(AC Output, Continuous Load) × 1.25 safety
Required Surge = Recommended Rating × Surge Allowance
| Panel Array | DC/AC 1.2 Inverter | Suggested Battery V | Typical Inverter Type |
|---|---|---|---|
| 3,000 W | 2.5 kW | 48V | String / Hybrid |
| 6,000 W | 5.0 kW | 48V | Hybrid |
| 10,000 W | 8.3 kW | 48V | Hybrid / String |
| 15,000 W | 12.5 kW | 48V (parallel) | 3-phase / Split |
Solar Inverters
Frequently Asked Questions
What is the DC-to-AC ratio?
It's the ratio of panel wattage to inverter rating. A 1.2 ratio means a 6,000W array on a 5,000W inverter. This slightly overpanels the inverter for better low-light output with minor midday clipping.
Do I need a bigger inverter for motor loads?
Yes. Motors like well pumps and AC compressors can draw 2–3× their running watts for a few seconds. Choose an inverter whose surge rating exceeds this, or oversize the continuous rating.
Hybrid vs. off-grid vs. string inverter?
String inverters are grid-tie only. Hybrid inverters handle grid-tie and battery charging. Off-grid inverters run standalone battery systems with no grid reference.