1. What is Solar Battery Capacity?

The solar battery capacity calculation determines the required battery bank size (in Amp-hours) to power your loads for a specified number of days, accounting for system efficiency and battery depth of discharge.

2. How Does the Calculator Work?

The calculator uses the solar battery capacity equation:

Where:

• \( Load_{Wh} \) — Daily energy consumption in Watt-hours
• \( Days \) — Desired days of autonomy (backup)
• \( Voltage \) — Battery bank nominal voltage
• \( DoD \) — Depth of discharge (fraction of battery capacity that can be used)
• \( Efficiency \) — System efficiency (inverter, wiring losses)

Explanation: The equation converts your daily energy needs to total storage required, then factors in battery characteristics and system losses.

3. Importance of Proper Sizing

Details: Correct battery sizing ensures reliable power availability while preventing over-sizing (costly) or under-sizing (reduced battery life).

4. Using the Calculator

Tips: Measure your daily consumption accurately. Typical DoD is 0.5-0.8 for lead-acid, 0.8-0.9 for lithium. System efficiency is typically 0.8-0.9.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical DoD value?
A: 0.5 for lead-acid (50% discharge), 0.8-0.9 for lithium batteries for optimal lifespan.

Q2: How do I find my daily load?
A: Sum the Watt-hours of all devices (Power in Watts × Hours used per day).

Q3: What voltage should I use?
A: Common system voltages are 12V, 24V, or 48V. Higher voltages reduce current and wiring costs.

Q4: Why include efficiency?
A: Real-world systems have losses (inverter ~90%, wiring ~5%). 85% is a good starting estimate.

Q5: How many days of autonomy?
A: 3-5 days is typical for off-grid. Grid-tied systems may use 1-2 days for backup.