Solar Panel Output Calculator

Enter System Inputs

Panel Wattage (W)

Number of Panels

Peak Sun Hours

System Efficiency (%)

Inverter Efficiency (%)

Temperature Loss (%)

Shading Loss (%)

Soiling Loss (%)

Tilt and Orientation Factor (%)

Annual Degradation Rate (%)

Days in Billing Month

Monthly Energy Load (kWh)

Electricity Tariff per kWh

Grid CO₂ Factor (kg/kWh)

Formula Used

1. DC Capacity (kW)
DC Capacity = (Panel Wattage × Number of Panels) ÷ 1000

2. Gross Daily Output (kWh)
Gross Daily Output = DC Capacity × Peak Sun Hours

3. Performance Ratio
Performance Ratio = System Efficiency × Inverter Efficiency × Temperature Factor × Shading Factor × Soiling Factor × Tilt Factor

4. Net Daily Output (kWh)
Net Daily Output = Gross Daily Output × Performance Ratio

5. Monthly Output (kWh)
Monthly Output = Net Daily Output × Days in Billing Month

6. Annual Output (kWh)
Annual Output = Net Daily Output × 365

7. Degradation Adjusted Annual Output (kWh)
Adjusted Annual Output = Annual Output × (1 − Degradation Rate)

8. Cost Savings and Carbon Reduction
Annual Savings = Adjusted Annual Output × Tariff Rate
CO₂ Avoided = Adjusted Annual Output × Grid CO₂ Factor

How to Use This Calculator

Enter the wattage rating of one solar panel.
Enter the total number of panels in the array.
Provide average daily peak sun hours for the site.
Fill in system efficiency and inverter efficiency percentages.
Add expected temperature, shading, and soiling losses.
Set the tilt and orientation factor for array alignment.
Enter degradation rate, billing days, tariff, and optional monthly load.
Press Calculate Output to display results above the form.
Use the CSV and PDF buttons to export the result summary.

Example Data Table

Panel Wattage (W)	Panels	Peak Sun Hours	System Efficiency (%)	Inverter Efficiency (%)	Combined Losses (%)	Monthly Output (kWh)
450	10	5.0	91	96	14	541.63
550	12	5.5	92	96	16	835.94
600	16	6.0	93	97	13	1420.32

FAQs

1. What does peak sun hours mean?

Peak sun hours represent equivalent full-strength sunlight received during a day. It simplifies varying solar irradiance into one useful design value for output estimation.

2. Why are shading and temperature losses important?

Both factors reduce real production. Even efficient modules can underperform when heat rises or shadows cover cells, so including these losses improves estimate accuracy.

3. What is a good performance ratio?

Many well-designed systems operate with performance ratios around 70% to 90%, depending on climate, equipment quality, wiring, inverter behavior, and maintenance conditions.

4. Does this calculator estimate financial savings?

Yes. It multiplies degradation-adjusted annual production by your tariff rate. This gives a quick estimate of annual electricity cost reduction.

5. What is specific yield?

Specific yield shows yearly energy produced per installed kilowatt of solar capacity. It helps compare sites or systems with different array sizes.

6. Why include degradation rate?

Solar modules slowly lose output over time. Degradation rate helps adjust expected annual energy, making long-term planning more realistic.

7. Can I use this for off-grid systems?

Yes, for generation estimation. However, off-grid design also needs battery sizing, autonomy days, charge controller limits, and inverter surge analysis.

8. Is the result exact for every location?

No. It is an engineering estimate. Actual output depends on weather variation, equipment quality, dirt buildup, cable losses, installation angle, and maintenance.