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Battery Capacity Formula:
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Battery capacity is a measure of the charge stored by the battery, typically measured in ampere-hours (Ah). It determines how much energy a battery can store and deliver to your solar power system.
The calculator uses the battery capacity formula:
Where:
Explanation: The formula converts your system's energy requirement from kWh to watt-hours (by multiplying by 1000), then divides by the battery voltage to get the capacity in ampere-hours.
Details: Proper battery sizing is crucial for solar systems to ensure you have enough stored energy to meet your needs during periods without sunlight. Undersized batteries may not provide enough power, while oversized batteries increase costs unnecessarily.
Tips: Enter your total system energy requirement in kWh and your battery bank voltage in volts. Both values must be positive numbers. The calculator will determine the required battery capacity in ampere-hours (Ah).
Q1: What's the difference between Ah and kWh?
A: Ampere-hours (Ah) measure charge capacity, while kilowatt-hours (kWh) measure energy. To convert between them, you need to know the voltage (kWh = Ah × V / 1000).
Q2: How do I determine my system energy needs?
A: Calculate the total wattage of all devices multiplied by hours of use per day, then divide by 1000 to get kWh.
Q3: What voltage should I use for my battery bank?
A: Common voltages are 12V, 24V, or 48V. Higher voltages are more efficient for larger systems.
Q4: Should I account for battery depth of discharge?
A: Yes, most batteries shouldn't be discharged completely. Multiply your calculated capacity by 1.2-1.5 for lead-acid or 1.1-1.2 for lithium to account for this.
Q5: How does temperature affect battery capacity?
A: Cold temperatures reduce battery capacity. In cold climates, you may need to increase capacity by 20-30%.