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Monthly Generation Plot
This plot shows projected monthly production using seasonal multipliers.
Example Data Table
| Item | Example Value | Meaning |
|---|---|---|
| Daily Energy Demand | 18.00 kWh/day | Average daily electricity requirement for the project. |
| Peak Sun Hours | 5.50 hours/day | Effective full-sun production window used for sizing. |
| System Efficiency | 78.00% | Overall performance after electrical and thermal losses. |
| Required Array Size | 5.73 kW | Recommended DC array capacity before panel rounding. |
| Recommended Panel Count | 11 panels | Rounded count based on 550 W modules. |
| Estimated Panel Area | 28.60 m² | Approximate module footprint required on the roof. |
| Expected Annual Generation | 9,473.39 kWh | Projected yearly energy from the rounded array size. |
Formula Used
1) Adjusted Daily Load
Adjusted Daily Load = Daily Energy × (1 + Load Growth) × (1 + Battery Allowance)
2) Effective Solar Yield
Effective Solar Yield = Peak Sun Hours × System Efficiency
3) Required Array Size
Required Array Size = (Adjusted Daily Load ÷ Effective Solar Yield) × (1 + Safety Margin) × (1 + Seasonal Loss Reserve)
4) Panel Count
Panel Count = Ceiling[(Required Array Size × 1000) ÷ Panel Wattage]
5) Actual Installed Capacity
Actual Array = Panel Count × Panel Wattage ÷ 1000
6) Area Estimate
Panel Area Total = Panel Count × Panel Area
7) Production Estimate
Daily Generation = Actual Array × Peak Sun Hours × System Efficiency
These equations create a practical first-pass design estimate. Final engineering should still review module spacing, orientation, tilt, shading, cable runs, inverter loading, structural limits, and local code requirements.
How to Use This Calculator
- Enter the site’s daily electricity need in kWh per day.
- Add average peak sun hours for the installation location.
- Set a realistic efficiency value for losses and operating conditions.
- Add safety, seasonal, growth, and battery reserves when needed.
- Enter module wattage and module area from the product sheet.
- Optionally add system voltage, inverter size, and roof area.
- Press the calculate button to view the result block above the form.
- Review required array size, panel count, energy output, roof fit, and engineering notes.
- Use the export buttons to save the result as CSV or PDF.
FAQs
1) What does solar array size mean?
Solar array size is the required DC capacity of your panel field. It helps determine how many modules you need to meet daily energy targets after accounting for real-world losses.
2) Why are peak sun hours important?
Peak sun hours convert local sunlight conditions into an effective production window. Lower values mean you need more installed capacity to deliver the same daily energy.
3) What should I enter for system efficiency?
Use a value that reflects inverter losses, temperature effects, wiring losses, mismatch, dirt, and shading. Many real projects use a combined performance range around 70% to 85%.
4) Why include a safety margin?
A safety margin protects against uncertainty in usage, weather variation, panel aging, and small design assumptions. It reduces the chance of undersizing the array.
5) What is seasonal loss reserve?
Seasonal reserve covers weaker winter irradiation, haze, lower sun angles, or recurring shading patterns. It is especially useful when your project must perform well during difficult months.
6) Why does the calculator show panel area?
Area matters because electrical sizing can look acceptable while physical placement fails. This value helps you compare required module footprint against available roof space.
7) What is the DC to AC ratio?
The DC to AC ratio compares panel capacity to inverter capacity. Ratios above one are common, but very high values can increase clipping during strong solar conditions.
8) Is this calculator enough for final installation design?
It is excellent for planning and scenario analysis, but final design should still confirm structure, orientation, spacing, cable sizing, protection devices, and local compliance requirements.