1. What is a 400W Solar Panel?

A 400W solar panel is a photovoltaic module with a nominal power output of 400 watts under standard test conditions (STC). These panels are commonly used in residential and commercial solar installations.

2. How Does the Calculator Work?

The calculator uses the solar power formula:

Where:

• 400 — Nominal wattage of the solar panel (W)
• Sunlight Hours — Average peak sunlight hours per day
• Efficiency — System efficiency percentage (typically 70-85%)
• Number of Panels — Quantity of 400W panels in the system

Explanation: The calculation accounts for real-world conditions by applying the system efficiency factor to the panel's rated output.

3. Importance of Solar Panel Calculations

Details: Accurate solar production estimates are crucial for system sizing, energy planning, and return on investment calculations. They help determine how many panels are needed to meet energy requirements.

4. Using the Calculator

Tips: Enter average daily sunlight hours (typically 3-6 hours depending on location), system efficiency (default is 75%), and number of panels. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What affects solar panel output?
A: Output depends on sunlight intensity, panel orientation, temperature, shading, and system losses (wiring, inverters, etc.).

Q2: How many 400W panels do I need?
A: Divide your daily kWh needs by the daily output of one panel. For example, if you need 20 kWh/day and each panel produces 1.5 kWh/day, you'd need about 14 panels.

Q3: What's a good system efficiency percentage?
A: Most grid-tied systems operate at 75-85% efficiency. Off-grid systems might be lower due to battery losses.

Q4: Can I use this for other panel sizes?
A: This calculator is specifically for 400W panels. For other sizes, replace 400 with the panel's wattage in the formula.

Q5: What about seasonal variations?
A: For accurate annual estimates, calculate for different seasons and average the results, as sunlight hours vary throughout the year.