Solar Power Converter

Solar panel energy output depends on panel wattage and sunlight hours.

Formula:

• Daily kWh = Panel Watts x Sun Hours x Efficiency / 1000
• Monthly kWh = Daily kWh x 30
• Yearly kWh = Daily kWh x 365

Typical efficiency factor: 0.75-0.85 (accounts for inverter losses, temperature, dirt, etc.)

Average peak sun hours by region:

• Arizona/Nevada: 6-7 hours
• California/Texas: 5-6 hours
• Midwest US: 4-5 hours
• Northeast US: 3.5-4.5 hours
• Northern Europe: 2.5-4 hours
• Australia: 4.5-6.5 hours

Common panel sizes:

• Residential panel: 300-400 watts
• Typical system (20 panels): 6-8 kW

Example:

• 400W panel x 5 sun hours x 0.80 efficiency = 1.6 kWh/day
• 20 panels = 8 kW system = 32 kWh/day = 960 kWh/month

The single most important idea here is the difference between power and energy, the thing people mix up constantly. Watts measure power, the rate of generation at an instant; watt-hours measure energy, the total produced over time. A panel’s wattage is its peak output under ideal lab sunlight, not what it makes across a real day.

Actual output is always lower, because the sun isn’t at full strength for more than a few hours. That’s why solar production is figured from “peak sun hours,” which compresses a day’s changing sunlight into an equivalent number of full-strength hours. A 400 W panel in a region with 4 peak sun hours makes roughly 1.6 kWh a day, not 9.6. When sizing a system, work backward from your daily energy use in kWh, then divide by your local sun hours to find the panel wattage you actually need, leaving a margin for wiring and inverter losses.