1. What is Battery Size Calculation?

The battery size calculation determines the required capacity (in ampere-hours) of a battery bank needed to power your solar system for a specified number of days without sunlight (autonomy days), considering your daily energy consumption and battery specifications.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• Solar System Load — Total wattage of your solar-powered devices
• Daily Use — Hours per day the system will be used
• Autonomy Days — Days of backup power needed
• Battery Voltage — Voltage of your battery bank (typically 12V, 24V, or 48V)
• Depth of Discharge — Percentage of battery capacity that can be safely used (typically 0.5 for lead-acid)

3. Importance of Proper Battery Sizing

Details: Correct battery sizing ensures your solar system can meet power demands during periods of low sunlight while maximizing battery life by not over-discharging.

4. Using the Calculator

Tips:

• For accurate results, sum the wattage of all devices that will run simultaneously
• Consider seasonal variations when choosing autonomy days
• Typical depth of discharge: 50% for lead-acid, 80% for lithium-ion batteries
• Round up to the nearest standard battery size

5. Frequently Asked Questions (FAQ)

Q1: What's a typical autonomy period?
A: 2-5 days is common, depending on location and reliability needs. More for areas with frequent cloudy days.

Q2: How does battery type affect the calculation?
A: Lithium batteries allow deeper discharge (higher DoD) and have longer cycle life than lead-acid.

Q3: Should I add a safety margin?
A: Yes, add 10-20% to account for battery aging and unexpected loads.

Q4: How does temperature affect battery capacity?
A: Cold temperatures reduce capacity - you may need to increase size by 20-30% in cold climates.

Q5: Can I mix different battery sizes?
A: Not recommended as it can lead to uneven charging and reduced battery life.