Battery Inverter Size Calculator

Inverter Size Formula:

\[ \text{Inverter Size (VA)} = \frac{\text{Battery Ah} \times \text{Voltage (V)}}{\text{Efficiency} \times \text{Load Factor}} \]

Battery Ah (amp-hours):

Voltage:

Efficiency:

(0-1)

Load Factor:

(0-1)

Inverter Size:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Inverter Size Calculation?

The inverter size calculation determines the appropriate capacity (in volt-amperes, VA) of an inverter needed to support a battery system based on the battery capacity, voltage, system efficiency, and expected load factor.

2. How Does the Calculator Work?

The calculator uses the inverter size formula:

\[ \text{Inverter Size (VA)} = \frac{\text{Battery Ah} \times \text{Voltage (V)}}{\text{Efficiency} \times \text{Load Factor}} \]

Where:

\( \text{Battery Ah} \) — Battery capacity in amp-hours
\( \text{Voltage} \) — System voltage in volts
\( \text{Efficiency} \) — Inverter efficiency (typically 0.8-0.95)
\( \text{Load Factor} \) — Expected average load (0-1)

Explanation: The equation accounts for battery capacity, system voltage, and derating factors for efficiency and typical load conditions.

3. Importance of Proper Inverter Sizing

Details: Correct inverter sizing ensures reliable power supply, prevents overloading, maximizes battery life, and improves system efficiency.

4. Using the Calculator

Tips: Enter battery capacity in Ah, system voltage in V, efficiency (typically 0.9), and load factor (typically 0.8). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical efficiency value for inverters?
A: Most modern inverters have efficiencies between 85-95% (0.85-0.95). High-quality pure sine wave inverters may reach 90-95%.

Q2: How do I determine the load factor?
A: Load factor is the ratio of average load to maximum load. For residential systems, 0.7-0.8 is common unless you know your specific usage pattern.

Q3: Should I add a safety margin to the calculated size?
A: Yes, it's recommended to add 20-25% to the calculated size to account for startup surges and future expansion.

Q4: Does this calculation consider surge capacity?
A: No, this calculates continuous power. Some appliances (like motors) require 3-7 times their rated power during startup.

Q5: How does battery type affect the calculation?
A: While the calculation is the same, different battery types (lead-acid, lithium) have different discharge characteristics that may affect actual performance.