Solar Panel Energy Calculator
The Solar Panel Energy Calculator estimates photovoltaic system output based on panel wattage, count, peak sun hours, tilt angle, latitude, and system efficiency. It provides daily/monthly/annual kWh production with a 12-month solar profile chart, optimal tilt angle calculation, capacity factor, and CO₂ savings — interactive features an AI chatbot cannot replicate. Free, no signup.
Presets
Results
System Capacity
8.00
kWp
Daily Energy
31.98
kWh/day
Monthly Energy
972.6
kWh/month
Annual Energy
11671
kWh/year
Capacity Factor
16.7%
CO₂ Saved/Year
4669
kg CO₂/year
Tilt Factor
0.999
Optimal Tilt Angle
32.2°
Monthly Energy Profile
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What is a Solar Panel Energy Calculator?
A Solar Panel Energy Calculator estimates the electrical energy output of a photovoltaic (PV) system based on panel specifications, geographic location, and installation parameters. It uses the fundamental formula: Energy = System Capacity × Peak Sun Hours × System Efficiency × Tilt Factor. Peak sun hours represent the equivalent hours of 1000 W/m² irradiance per day, varying from 3-4 hours in cloudy regions to 7-8 hours in deserts. System efficiency (typically 75-85%) accounts for inverter losses, wiring losses, soiling, and temperature derating. The calculator also models seasonal variation using solar declination angles to provide monthly production estimates.
How to Use This Calculator
- Enter your solar panel wattage (typically 300-550 Wp) and the number of panels
- Set peak sun hours for your location (check NASA POWER database or local solar maps)
- Adjust system efficiency (default 80% accounts for inverter, wiring, and thermal losses)
- Enter tilt angle and latitude for seasonal correction (optimal tilt ≈ latitude × 0.87)
- View daily, monthly, and annual energy production with the 12-month profile chart
Frequently Asked Questions
How many kWh does a solar panel produce per day?
A typical 400W panel produces 1.2-3.2 kWh/day depending on location. In a sunny area with 5 peak sun hours and 80% system efficiency, a 400W panel generates: 0.4 kW × 5 h × 0.80 = 1.6 kWh/day. In desert regions with 7+ sun hours, the same panel can reach 2.2 kWh/day. Cloudy regions with 3 sun hours yield about 0.96 kWh/day.
What is the optimal tilt angle for solar panels?
The optimal fixed tilt angle is approximately your latitude multiplied by 0.87 for annual energy maximization. For example, at 35° latitude, optimal tilt is about 30°. Steeper angles favor winter production while shallower angles favor summer. A seasonal adjustment of ±15° can increase annual output by 5-10% compared to fixed mounting.
What does system efficiency include?
System efficiency (typically 75-85%) accounts for all losses between panel DC output and usable AC energy: inverter conversion (96-98%), wiring losses (1-3%), soiling and dust (2-5%), temperature derating (5-15% in hot climates), and module mismatch (1-2%). High-quality installations with microinverters can achieve 82-85% overall efficiency.
How much CO₂ do solar panels save?
Solar panels save approximately 0.4 kg CO₂ per kWh generated (global grid average). A typical 6 kWp residential system producing 8,000 kWh/year saves about 3,200 kg CO₂ annually — equivalent to driving 13,000 km less in a gasoline car. Over a 25-year panel lifetime, this totals 80 tonnes of avoided emissions.