1. What is the Battery Size Calculation?

The battery size calculation determines the required capacity (in ampere-hours) of a battery bank needed to power an off-grid system for a specified number of days, based on your daily energy consumption and system voltage.

2. How Does the Calculator Work?

The calculator uses the following equation:

Where:

• \( \text{Off Grid Wh} \) — Your daily energy consumption in watt-hours
• \( \text{Days} \) — Number of days of autonomy needed
• \( \text{V} \) — System voltage (typically 12V, 24V, or 48V)

Explanation: The equation converts your total energy requirement (Wh) into battery capacity (Ah) by accounting for your system voltage.

3. Importance of Battery Sizing

Details: Proper battery sizing is crucial for off-grid systems to ensure you have enough stored energy to meet your needs during periods of low solar production.

4. Using the Calculator

Tips: Enter your daily energy consumption in watt-hours, number of days of autonomy needed, and your system voltage. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine my daily Wh consumption?
A: Add up the wattage of all devices multiplied by their daily usage hours, or use an energy monitor to measure actual consumption.

Q2: What's a typical number of days of autonomy?
A: 3-5 days is common, depending on your location's weather patterns and how critical your power needs are.

Q3: Should I account for battery depth of discharge?
A: Yes, this calculation gives raw Ah. Divide by your battery's recommended depth of discharge (e.g., 0.5 for 50% DoD) for actual battery size.

Q4: What system voltage should I use?
A: Small systems often use 12V, medium systems 24V, and larger systems 48V. Match your inverter's input voltage.

Q5: Does this account for inefficiencies?
A: No, you should multiply the result by about 1.2 to account for typical system losses.