1. What is the Battery Capacity Equation?

The battery capacity equation calculates the required battery bank size (in amp-hours) for a solar power system based on your daily energy needs, desired days of autonomy, battery voltage, and acceptable depth of discharge.

2. How Does the Calculator Work?

The calculator uses the battery capacity equation:

Where:

• Panel Daily Output — Total energy your solar panels generate per day (in watt-hours)
• Autonomy Days — Number of days the system should run without sun
• Battery Voltage — Voltage of your battery bank (typically 12V, 24V, or 48V)
• Depth of Discharge — Percentage of battery capacity you can safely use (typically 0.5 for lead-acid, 0.8 for lithium)

Explanation: The equation determines how much battery storage you need to meet your energy requirements during periods without solar charging.

3. Importance of Battery Sizing

Details: Proper battery sizing ensures your solar system can meet your power needs during cloudy days or at night, while avoiding over-sizing which increases cost.

4. Using the Calculator

Tips: Enter your daily energy production from solar panels, how many days of backup you want, your battery bank voltage, and the maximum safe depth of discharge for your battery type.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical depth of discharge?
A: 50% for lead-acid batteries, 80% for lithium-ion batteries to maximize battery life.

Q2: How many autonomy days should I plan for?
A: Typically 2-5 days depending on your location's weather patterns and reliability needs.

Q3: What if my system uses different battery voltages?
A: The calculator works for any voltage (12V, 24V, 48V etc.) - just enter your system's voltage.

Q4: Should I add a safety margin?
A: Yes, consider adding 20-25% to the calculated capacity to account for inefficiencies and aging.

Q5: How does temperature affect battery capacity?
A: Cold temperatures reduce battery capacity - you may need to increase capacity by 10-20% in cold climates.