Use the **Solar Power Calculator** below to estimate your potential annual energy production and financial savings by installing a residential solar photovoltaic (PV) system.
Solar Power Calculator
Estimated Annual Savings:
$0.00Detailed Calculation Steps:
Solar Power Calculator Formula:
Annual Energy (kWh) = System Size (kW) × Sun Hours (h/day) × 365 days × (Efficiency / 100)
Annual Savings ($) = Annual Energy (kWh) × Electricity Rate ($/kWh)
Formula Source Citations:
U.S. Department of Energy – PV Design Solar Energy Industries Association (SEIA)Variables:
- System Size (kW): The rated direct current (DC) capacity of your solar panel array (e.g., 7.5 kW). This determines the maximum amount of power the system can produce.
- System Performance Ratio (%): Represents the efficiency of the entire system, accounting for losses from the inverter, wiring, shading, and temperature. Typically ranges from 75% to 85%.
- Average Daily Sun Hours (hours/day): The average number of hours per day your system receives effective peak sunlight. This is heavily dependent on geographic location and roof orientation.
- Residential Electricity Rate ($/kWh): The price you pay your utility company per kilowatt-hour of electricity consumed. This is crucial for calculating savings.
Related Calculators:
- Solar Payback Period Calculator
- Energy Consumption Estimator
- Return on Investment (ROI) Calculator
- CO2 Emissions Savings Calculator
What is Solar Power Calculator?
A solar power calculator is an essential tool for homeowners and businesses considering a solar installation. It provides a preliminary financial estimate by translating technical inputs (like system size and sun exposure) into tangible outputs, primarily annual energy production in kilowatt-hours (kWh) and resulting cost savings in local currency.
The primary purpose is de-risking the decision-making process. By simulating various scenarios—adjusting for panel efficiency, local electricity rates, or different system sizes—users can gain a clear understanding of the project’s financial viability before engaging with installers. It helps set realistic expectations for energy independence and long-term return on investment (ROI).
How to Calculate Solar Power Savings (Example):
Using the example inputs (7.5 kW, 80% Performance, 4.5 Sun Hours, $0.15/kWh):
- Calculate Daily Energy (kWh): 7.5 kW × 4.5 hours × (80 / 100) = 27 kWh per day.
- Calculate Annual Energy (kWh): 27 kWh/day × 365 days/year = 9,855 kWh per year.
- Calculate Annual Savings ($): 9,855 kWh × $0.15/kWh = $1,478.25 in annual electricity savings.
- Estimate Payback: If the total system cost is $25,000, the simple payback period is $25,000 / $1,478.25 ≈ 16.9 years (before tax credits or incentives).
Frequently Asked Questions (FAQ):
A: Calculators provide a good estimate but should not replace a professional site assessment. The calculation relies on averages for efficiency and sun hours, while a professional design accounts for roof angles, precise shading, and specific component specifications.
A: Geographic location (which dictates the average daily sun hours) and system size are the biggest factors. A highly efficient system in a cloudy region may produce less energy than a moderately efficient system in a sunny region.
A: Use your current electricity rate ($/kWh). Savings are based on the cost of the electricity you no longer have to purchase from the utility. Be sure to use the rate excluding fixed service fees.
A: The PR is the ratio of the actual energy output of the solar system compared to the energy it *should* theoretically produce. It accounts for all non-ideal factors like dust, cable losses, temperature, and inverter inefficiencies, usually landing between 75% and 85%.