1. What is the Solar Battery Size Calculation?

The Solar Battery Size calculation determines the required battery capacity (in amp-hours) for a solar power system based on your daily energy consumption, desired days of autonomy, and system voltage.

2. How Does the Calculator Work?

The calculator uses the following equation:

Where:

• UK Daily Wh — Your daily energy consumption in watt-hours
• Autonomy — Number of days you want the battery to last without solar input
• V — System voltage (typically 12V, 24V, or 48V for solar systems)

Explanation: The equation converts your daily energy needs into battery capacity by accounting for your desired backup duration and system voltage.

3. Importance of Proper Battery Sizing

Details: Correct battery sizing ensures your solar system can meet your energy needs during periods of low sunlight while avoiding unnecessary costs from oversizing.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: How do I determine my daily Wh usage?
A: Check your electricity bills or use an energy monitor to measure your daily consumption. UK households average about 8-10kWh per day.

Q2: What's a typical autonomy period?
A: For UK conditions, 2-3 days autonomy is common to account for cloudy periods, but this depends on your needs and budget.

Q3: What system voltage should I use?
A: Small systems use 12V, medium systems 24V, and larger systems 48V. Higher voltages reduce current and allow thinner cables.

Q4: 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 efficiency losses.

Q5: Does this account for battery depth of discharge?
A: No, for lead-acid batteries you should divide the result by 0.5 (for 50% DoD). Lithium batteries can typically use 80-100% of their capacity.