- Solar Production Calculator
Solar Production Calculator
Estimate how much electricity your solar panels could generate each day, month, and year. Use our free solar production calculator to explore how sunlight, system size, panel direction, and shading affect your energy output.
- Free to use
- Planning Tool
- Instant estimate
SOLAR ENERGY ESTIMATE
Calculate Your Solar Production
Estimate solar electricity in kWh using your system size, local peak sun hours, panel direction, shade and age.
Your Solar Energy Estimate
Planning estimateResults are illustrative; not a site-specific solar forecast.
Estimated Monthly Production
Illustrative seasonality, not measured monthly weather data.
The twelve monthly bars are normalized to match the annual energy estimate.
On narrow screens, swipe the chart sideways to view all 12 months.
View monthly figures as a table
| Month | Estimated kWh |
|---|
How to Use the Calculator
Follow these three simple steps to estimate your solar panel energy production.
STEP 01
Enter your system details
Select your solar system size in kilowatts (kW). Choose a location preset or enter your average peak sun hours. Use your planned or existing solar panel capacity for a more useful estimate.
STEP 02
Adjust Solar Conditions
Choose your panel direction, shading level, and system age. These settings affect how much electricity your solar panels can generate. Use realistic conditions instead of assuming every day will be sunny.
STEP 03
Review Your System Estimate
Click Calculate Production to view your daily, monthly, and annual solar output in kWh. Check seasonal trends and adjust inputs to compare results.
Understanding Your Results
Learn what your solar production results mean and how to use them when planning a solar system.
Daily Solar Output
Shows the average electricity your solar panels may generate each day, measured in kilowatt-hours (kWh). Actual daily production changes with weather, sunlight, temperature, and seasonal conditions.
Monthly Solar Output
Estimates your average monthly electricity generation based on annual production. The monthly chart shows an illustrative seasonal pattern, helping you understand why solar output can change throughout the year.
Annual Production
Shows the estimated electricity your photovoltaic system may produce in one year. This figure accounts for the selected sunlight, panel direction, shading, and system age assumptions.
Peak Sun Hours (PSH)
Represents the average daily solar energy available at your location. Higher peak sun hours generally increase electricity production. Use realistic annual averages rather than the sunniest day’s conditions.
System Efficiency
Shows how energy losses affect your estimated solar electricity production. The calculator uses an 80% overall system performance factor before applying direction, shading, and age adjustments. Real performance varies with inverter efficiency, panel temperature, wiring losses, dust, and equipment condition. Understanding these factors helps you compare estimates and set realistic expectations for long-term solar output.
If you’re still deciding how much solar capacity your home needs, start with our Solar System Size Calculator to estimate the required system size. Once you know your expected annual electricity production, use the Solar ROI Calculator to explore installation payback and long-term financial performance.
How Solar Production Is Calculated
Solar panels convert sunlight into electricity. The amount generated depends on your installed system capacity, available sunlight, and operating conditions.
Solar Production Formula
Annual Solar Output (kWh) = System Size (kW) × Peak Sun Hours × 365 × 0.80 × Direction Factor × (1 − Shading Loss) × Age Factor
Practical Example
A new 5 kW solar system receiving 5 peak sun hours per day, with favorable orientation and no shading, produces:
5 × 5 × 365 × 0.80 = 7,300 kWh/year
That’s approximately 20 kWh per day or 608 kWh per month, on average.
This is a simplified estimate, not a location-specific weather forecast.
How to Calculate Solar Power Generation in kWh
Solar electricity generation can be estimated by multiplying the installed system capacity (kW) by average daily peak sun hours and a system performance factor.
For example, a 6 kW solar system receiving 4.5 peak sun hours per day, with an assumed 80% performance factor, generates:
6 × 4.5 × 0.80 = 21.6 kWh per day
Over 30 days, that equals approximately 648 kWh under the same average conditions.
Actual production varies with sunlight, shading, temperature, panel orientation, and equipment performance.
System Size: Larger solar arrays can produce more electricity when sunlight and other conditions stay the same. System capacity is measured in kilowatts and depends on the combined rated power of your solar panels.
Sunlight Hours: Peak sun hours measure usable solar energy, not total daylight time. Local weather, latitude, and seasonal sunlight patterns influence how much energy your solar panels can generate.
Efficiency Losses: Inverters, wiring, temperature, and dust can reduce usable electricity production. This calculator applies a simplified performance factor, while panel direction and shading are modeled separately.
Seasonal Variation: Solar production changes throughout the year as sunlight hours and weather conditions vary. Monthly output estimates help illustrate these changes, but actual generation depends on local climate.
Solar Energy Flow: From Sunlight to Electricity
See how sunlight becomes usable electricity in a typical solar power system.
1. Sunlight
Sunlight provides energy for solar panels.
2. Solar Panels
Convert sunlight into direct current electricity.
3. Inverter
Converts DC electricity into usable AC.
4. System Losses
Heat, shading, and wiring reduce output.
5. Usable Energy
Electricity powers appliances at your home.
Frequently Asked Questions
Common questions about solar energy generation estimates, peak sun hours, and real-world performance factors.
How much electricity does a 5 kW solar system produce?
A 5 kW solar system with five peak sun hours and an 80% performance factor produces approximately 20 kWh daily or 7,300 kWh annually before additional direction, shading, or age losses. Actual production depends on location and equipment.
How many kWh do solar panels produce per day?
Daily output depends on system size and available sunlight. For example, a 4 kW system receiving five peak sun hours produces approximately 16 kWh per day with an 80% performance factor and no additional losses.
What are peak sun hours?
Peak sun hours represent the daily solar energy received, expressed as equivalent hours at a standard sunlight intensity. They are different from daylight hours and help estimate solar panel electricity generation.
Does shading reduce solar panel production?
Yes. Trees, nearby buildings, and roof obstructions can block sunlight and reduce electricity generation. The actual loss depends on when shading occurs, which panels are affected, and the system configuration.
Do solar panels produce the same energy every month?
No. Solar output varies with seasons, weather, and sunlight availability. Your monthly production chart provides a simplified seasonal estimate rather than exact future electricity generation.
How accurate is this solar production calculator?
It provides useful preliminary estimates based on your inputs and simplified system assumptions. For a location-specific forecast, compare results with NREL’s PVWatts Calculator, which uses solar resource and system information to model electricity production.
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Important: Solar production results are planning estimates, not guaranteed energy output. Actual generation varies with local weather, roof orientation, panel tilt, temperature, shading, equipment performance, and maintenance.