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

Panel Wattage (Wp) (Wp)

Number of Panels

Peak Sun Hours (h/day) (h/day)

System Efficiency (%) (%)

Tilt Angle (°) (°)

Azimuth Angle (°) (°)

Latitude (°) (°)

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.