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Solar Power Battery Calculator

Battery Size Formula:

\[ \text{Battery Size (Ah)} = \frac{\text{Load (Wh)} \times \text{Days (days)}}{\text{DOD} \times \text{Voltage (V)}} \]

Wh
days
(0-1)
V

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1. What is a Solar Power Battery Calculator?

Definition: This calculator determines the required battery bank size for solar power systems based on your energy needs and system parameters.

Purpose: It helps solar installers and DIY enthusiasts properly size battery banks for off-grid or backup power systems.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \text{Battery Size (Ah)} = \frac{\text{Load (Wh)} \times \text{Days of Autonomy}}{\text{DOD} \times \text{System Voltage}} \]

Where:

Explanation: The formula calculates how much battery capacity you need to power your loads for the specified days while respecting the battery's recommended discharge depth.

3. Importance of Proper Battery Sizing

Details: Correct battery sizing ensures reliable power availability, prolongs battery life by preventing excessive discharge, and helps optimize system costs.

4. Using the Calculator

Tips: Enter your daily energy consumption in Wh, desired days of autonomy (typically 1-3), depth of discharge (0.5 for lead-acid, 0.8 for lithium), and system voltage. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical DOD value?
A: For lead-acid batteries use 0.5 (50% discharge), for lithium batteries use 0.8 (80% discharge).

Q2: How do I find my daily load in Wh?
A: Multiply appliance wattage by hours used per day, then sum all appliances.

Q3: What's a good days of autonomy value?
A: 1-3 days is typical. More days provide more backup but increase cost.

Q4: Should I round up the battery size?
A: Yes, always round up to the nearest standard battery size available.

Q5: Does this include efficiency losses?
A: No, consider multiplying the result by 1.1-1.2 to account for system inefficiencies.

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