1. What is the Battery Size Calculation?

The battery size calculation determines the required battery capacity (in amp-hours) 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:

• \( \text{Off Grid Wh} \) — 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 without power generation (like cloudy days for solar systems).

4. Using the Calculator

Tips: Enter your daily energy consumption in watt-hours, the number of days you want your system to run without charging, and your system voltage. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine my daily Wh usage?
A: Multiply the wattage of each appliance by hours used per day, then sum all appliances. Energy monitors can provide accurate measurements.

Q2: What's a typical days of autonomy value?
A: 3-5 days is common for solar systems, depending on location and weather patterns.

Q3: Should I add a safety margin?
A: Yes, it's recommended to add 20-30% to the calculated size to account for battery aging and unexpected usage.

Q4: Does this account for battery depth of discharge?
A: No, divide your result by your battery's recommended depth of discharge (e.g., 0.5 for 50% DoD) for actual required capacity.

Q5: What about inverter efficiency?
A: For AC systems, divide your Wh requirement by inverter efficiency (typically 0.9 for 90% efficient inverters) before calculation.