1. What is Terminal Voltage?

Terminal voltage (V_t) is the actual voltage available at the output terminals of a solar panel when it's under load. It differs from the open-circuit voltage (V_oc) due to internal resistance and current flow.

2. How Does the Calculator Work?

The calculator uses the terminal voltage equation:

Where:

• \( V_t \) — Terminal voltage (V)
• \( V_{oc} \) — Open circuit voltage (V)
• \( I \) — Current (A)
• \( R_s \) — Series resistance (Ω)

Explanation: The equation accounts for voltage drop across the internal series resistance of the solar panel when current is flowing.

3. Importance of Terminal Voltage Calculation

Details: Accurate terminal voltage calculation is crucial for designing solar power systems, determining actual power output, and ensuring proper matching with battery banks or inverters.

4. Using the Calculator

Tips: Enter open circuit voltage in volts, current in amperes, and series resistance in ohms. All values must be non-negative.

5. Frequently Asked Questions (FAQ)

Q1: Why does terminal voltage decrease with increasing current?
A: As current increases, the voltage drop across the internal series resistance (I×R_s) increases, reducing the available terminal voltage.

Q2: What is a typical series resistance value for solar panels?
A: Series resistance values vary by panel type and quality, but typically range from 0.1 to 1.0 ohms for standard silicon solar panels.

Q3: How does temperature affect terminal voltage?
A: Higher temperatures generally decrease both open-circuit voltage and increase series resistance slightly, reducing terminal voltage.

Q4: Can terminal voltage be higher than open-circuit voltage?
A: No, terminal voltage is always less than or equal to open-circuit voltage due to the voltage drop across internal resistance.

Q5: How is this calculation useful for system design?
A: It helps determine the actual operating voltage of solar panels under load, which is essential for proper system sizing and component selection.