Solar Calculator

Category: Ecology Author: Henrick Yau
- June 14, 2025
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Calculate solar panel system requirements, energy production, and financial returns for residential and commercial installations. This calculator helps homeowners and businesses evaluate solar energy potential and system sizing.

Location & Site Information

°
Positive for North, negative for South
°
Positive for East, negative for West
Average daily solar energy availability
°
0° = flat, 90° = vertical

Energy Requirements

kWh
Check your electricity bill

Solar Panel Specifications

W
%

Financial Parameters

%
Federal and local incentives
%
Credit rate for excess energy
%/year

Advanced Settings

%
Inverter, wiring, shading losses
years

Solar Energy Fundamentals

Solar photovoltaic systems convert sunlight directly into electricity through the photovoltaic effect. System sizing depends on energy needs, available solar resource, panel efficiency, and site-specific factors.

Key Solar Parameters
  • Solar Irradiance: Amount of solar energy received per unit area (kWh/m²/day)
  • Peak Sun Hours: Equivalent hours of full sun per day
  • Panel Efficiency: Percentage of sunlight converted to electricity
  • System Losses: Energy lost due to inverters, wiring, and shading
  • Capacity Factor: Actual vs. theoretical energy production ratio
  • Degradation Rate: Annual decrease in panel performance
System Components
  • Solar Panels: Convert sunlight to DC electricity
  • Inverters: Convert DC to AC electricity for home use
  • Mounting System: Secure panels to roof or ground
  • Monitoring: Track system performance and energy production
  • Net Meter: Measure energy consumed and exported to grid
  • Battery Storage: Store excess energy for later use (optional)
Financial Considerations
  • Payback Period: Time to recover initial investment
  • LCOE: Levelized Cost of Energy over system lifetime
  • NPV: Net Present Value of investment
  • IRR: Internal Rate of Return
  • Tax Credits: Federal and state incentives reducing system cost
  • Net Metering: Credit for excess energy sent to grid

Disclaimer: This calculator provides estimates based on typical solar system performance and should not replace professional solar assessment. Actual energy production and financial returns may vary based on local conditions, equipment selection, installation quality, and utility policies. Consult qualified solar installers and financial advisors for detailed analysis.

System Size Required:

$$ \text{Size (kW)} = \frac{\text{Target Production (kWh)}}{\text{Solar Hours} \times 365 \times \text{System Efficiency}} $$

Annual Production:

$$ \text{Production (kWh/year)} = \text{System Size (kW)} \times \text{Solar Hours} \times 365 \times \text{System Efficiency} $$

What Is the Solar Energy Calculator?

This Solar Energy Calculator helps homeowners and businesses estimate how large a solar panel system they need, how much energy it can produce each year, and how long it takes to pay back the cost. It also shows potential savings and environmental benefits.

How to Use the Calculator

  • Select your location or enter latitude and longitude to get local solar data.
  • Enter your average daily solar irradiance or peak sun hours.
  • Choose your roof orientation (south, east, west, etc.) and tilt angle.
  • Provide your monthly electricity usage and cost per kWh from your utility bill.
  • Decide what percentage of your usage you want the system to cover (100%, 75%, custom, etc.).
  • Select panel type, wattage, efficiency, and available roof area.
  • Enter system cost details, incentives, net metering rate, and expected annual degradation.
  • Click “Calculate Solar System” to see results. Use “Reset” to start over.

Key Benefits

This tool offers:

  • Clear solar system sizing for accurate solar system sizing and solar panel cost analysis.
  • Estimates of solar energy output and solar energy potential based on your site.
  • Financial insights including solar power estimate and solar energy savings.
  • Environmental impact, such as CO₂ avoided and equivalent trees planted.
  • Comparison of different panel types and cost scenarios.

Why This Calculator Helps You

You can:

  • Plan the right system size to match your energy needs.
  • Compare costs before and after tax credits and incentives.
  • Track potential annual savings and payback period.
  • See lifetime environmental benefits, reducing your household carbon footprint.
  • Make informed decisions without deep technical knowledge.

Frequently Asked Questions

How accurate are the results?

Results use typical efficiency and loss factors. They are estimates. For exact quotes, contact a solar installer.

What if my roof has shading?

System losses include wiring, inverter, and shading. For heavy shading, increase the loss percentage or consider microinverters.

Can I change panel types later?

Yes. You can select different panel types (monocrystalline, polycrystalline, thin film, bifacial) to see how efficiency and cost change.

Do I need to enter my exact coordinates?

No. You can select a nearby city or enter average solar irradiance manually if you don’t know your coordinates.

What does “net metering rate” mean?

Net metering rate is the credit you receive for extra solar energy sent back to the grid. Enter it as a percentage of your retail electricity rate.

How do I interpret the payback period?

Payback period shows how many years until savings cover your net system cost. A shorter period means faster return on Investment.