Solar Production Calculator

Find out how much electricity your solar system can generate each day, month, and year.

Enter the size of your solar system, select a sunlight profile or add your peak sun hours, and set the efficiency ratio. The calculator will estimate your expected solar output in kilowatt hours (kWh).

Actual solar output may vary with weather, location, shading, temperature, panel position, equipment performance and installation conditions.

What does the solar production calculator show?

The calculator gives you three main production figures: daily, monthly and annual solar production.

Daily solar production

Daily production shows how much electricity your solar system can produce during an average day based on the values you entered.

The result is shown in:

kWh per day

For example, if the result is 20 kWh per day , the system is estimated to produce approximately 20 units of electricity during that day.

For measuring electricity, 1 unit = 1 kilowatt hour (kWh).

Monthly solar production

Monthly production is estimated by how much electricity the system can produce over the number of days entered.

The basic calculation is:

Daily production × number of days = Monthly production

For example, if your system produces an estimated 20 kWh per day and you select 30 days:

20 × 30 = 600 kWh/month

Actual monthly yield may change as sunlight and weather conditions vary throughout the year.

Annual solar production

Annual production is an estimate of how much electricity your solar system can produce in 365 days.

This figure is useful when comparing:

•  Solar system capabilities.
•  Annual electricity consumption
•  Different solar configurations
•  Expected long-term energy needs

The annual yield is an estimate rather than a fixed amount because solar conditions change throughout the year.

How to use the solar production calculator?

1. Enter the size of your solar system.

Enter the rating capacity of the solar system you want to test.

For example:

•  3 kW
•  5 kW
•  7 kW
•  10 kW
•  20 kW

The capacity of the solar system in kilowatts, not your monthly electricity consumption.

kW vs kWh

These two terms measure different things.

• kW measures the power or rated capacity of your solar system.
• kWh measures the amount of electricity generated or used over time.

For example, a solar system may be rated at 5 kW , while its daily output may be 20 kW .

2. Select a sunlight profile or enter peak sun times.

Choose one of the available sunlight profiles for a quick calculation. If you already know the peak sun times for your location, enter your own in the Custom Sun Times field. A custom value greater than zero overrides the preset sunlight profile.

What are the peak sun hours?

Peak sun times are not the same as the number of hours between sunrise and sunset. They represent the equivalent number of hours during which the day’s solar energy will be equal to full solar radiation.

A place may receive many hours of daylight but significantly less during peak sun hours. Using peak sun times gives you a more meaningful solar yield calculation than entering total daylight hours.

3. Set the performance ratio.

The efficiency ratio measures the difference between the theoretical solar output and the actual system output expected to be generated. The calculator uses 0.75 as its default performance ratio. An efficiency ratio of 0.75 means that approximately 75% of the theoretical is used in the calculation:

System size × peak sun hours

This allows for common system vulnerabilities such as:

•  Disadvantages of the inverter
•  Wiring Disadvantages
•  Dust and dirt
•  Other derating systems

If there is a more appropriate performance ratio for your installation, you can enter that instead.

4. Enter the number of days.

Enter the number of days you want to use for monthly calculations.For a simple monthly estimate, you can use: 30 days. You can also change this value if you want to calculate production over a different period.

5. Choose a seasonal setting.

Solar energy production does not remain the same throughout the year. Seasonal changes in sunlight and weather can affect the amount of electricity generated each month. The seasonality option applies month-to-month fundamental variations to production estimates. For detailed monthly forecasts, site-specific solar and weather data will provide a more accurate estimate.

6. Calculate your solar yield.

Select Calculate to see your estimate :

•  Daily solar production
•  Monthly solar production
•  Annual solar production

You can then change system size, peak sun hours, or efficiency ratios to compare different scenarios.

How is solar energy production calculated?

The calculator uses three main inputs:

•  Size of the solar system
•  Peak sun hours
•  Performance ratio

Daily solar production formula

The basic formula is:

Daily production = System size × Peak sun hours × Efficiency ratio

Suppose you have:

System size: 5 kW
Peak sun hours: 5.5 hours per day
Efficiency ratio: 0.75

The calculation is:

5 × 5.5 × 0.75 = 20.625 kWh/day

So your estimated daily production will be approximately:

20.63 kilowatt-hours

Monthly solar production formula

Monthly production is calculated as follows:

Daily production × number of days

30 days of use:

20.625 × 30 = 618.75 kWh/month

Annual solar yield formula

The annual production is calculated as follows:

Daily production × 365

Using the same example:

20.625 × 365 = 7,528.125 kWh/year

This is approximately equal to:

7,528 kWh per year

Real-world output may vary as sunlight, temperature, weather, shading, and system performance change over time.

Peak sun hours vs. daylight hours

Peak sun hours are one of the most important inputs when estimating solar energy production. They should not be confused with normal daylight hours.

Daylight hours

Daylight hours measure the time between sunrise and sunset. A solar panel does not operate at full rated output throughout this period. Sunlight is weak in the early morning and late afternoon, and production can also be affected by clouds, haze, and weather conditions.

Peak sun hours

Peak sun times combine the solar energy received throughout the day into an equal number of hours at full solar irradiance. This makes them much more useful for estimating solar energy production. 

Using total daylight hours instead of peak sun hours can significantly increase expected yields. If you don’t know the peak sun times for your location, use the calculator’s built-in sunlight profile.

What is the solar efficiency ratio?

The efficiency ratio shows the difference between the theoretical output of a solar system and the expected electricity after real-world losses.No solar installation operates at its theoretical maximum under all conditions.

What can reduce the efficiency of a solar system?

Common disadvantages include:

•  Disadvantages of inverter replacement
•  Disadvantages of electrical wiring
•  Dust and dirt
•  High panel temperature
•  The goods do not match.
•  Shading
•  System downtime

The efficiency ratio combines these effects into a single value for calculation.

Examples of performance ratios.

Performance ratio:

• 1.00 = 100% of theoretical yield with no loss
• 0.80 = 80% theoretical yield
• 0.75 = 75% theoretical yield

Since this value directly affects the calculated generation, choose a realistic efficiency ratio when comparing solar systems.

Examples of solar energy production.

The following examples illustrate how system capacity, peak sun hours, and efficiency ratio affect power generation.

Example 1: 3 kW solar system

Suppose you enter:

• System size: 3 kW
• Peak sun hours: 4.5 hours per day
• Efficiency ratio: 0.70
• Days per month: 30

Daily production

3 × 4.5 × 0.70 = 9.45 kWh per day

Monthly production

9.45 × 30 = 283.5 kWh/month

Annual production

9.45 × 365 = 3,449.25 kWh/year

This example shows the estimated output of a small solar system using relatively conservative sun hours and efficiency values.

Example 2: 5 kW solar system

Suppose you enter:

• System size: 5 kW
• Peak sun hours: 5.5 hours per day
• Efficiency ratio: 0.75
• Days per month: 30

Daily production

5 × 5.5 × 0.75 = 20.625 kWh/day

Monthly production

20.625 × 30 = 618.75 kWh/month

Annual production

20.625 × 365 = 7,528.125 kWh/year

This example shows how a 5 kW system performs using the calculator’s 0.75 efficiency ratio.

Example 3: 10 kW solar system

Suppose you enter:

• System size: 10 kW
• Peak sun hours: 5.2 hours per day
• Efficiency ratio: 0.78
• Days per month: 30

Daily production

10 × 5.2 × 0.78 = 40.56 kWh/day

Monthly production

40.56 × 30 = 1,216.8 kWh/month

Annual production

40.56 × 365 = 14,804.4 kWh/year

This type of calculation can help large homes and businesses compare expected solar output with their electricity consumption.

What affects solar panel production?

Several factors can cause actual solar yield to differ from calculated results.

Location

Available solar energy varies in different cities and regions. Therefore, two identical solar systems installed in different locations can produce different amounts of electricity.

Weather

Clouds, rain, haze, and seasonal weather can reduce the amount of solar energy reaching the panels. Daily production will naturally vary with changes in weather conditions.

Panel direction

The direction your panels face affects when and how much sunlight reaches them. Panel orientation is not listed separately in this calculator.

Panel tilt

The angle of solar panels can also affect energy production. The calculator does not use roof or panel tilt as individual inputs.

Shading

Shadows from nearby objects can reduce solar output.

Common sources of solar shading

These may include:

•  Tree
•  Nearby buildings.
•  Water tanks
•  Parapet walls.
•  Other roof structures

Use a separate solar shade calculator to assess the impact of shading on your solar system performance, as shading is not calculated separately in this solar production calculator.

Dust and dirt

Dust and dirt on solar panels can reduce the amount of sunlight reaching the cells. Cleaning requirements will vary depending on the site and local conditions.

Temperature

Solar panel output can change as the module temperature increases or decreases.Instead of calculating temperature losses separately, this calculator uses an efficiency ratio to represent combined system losses.

Inverter and power losses

Some power is lost during the transfer of power from the inverter, wiring, and other system components. These losses are broadly included in the performance ratio rather than counted individually.

Equipment performance

Solar panels, inverters, and other components vary in performance and operating characteristics. The condition of the equipment can also affect production over time.

Weather conditions

Solar energy production varies throughout the year. System output during a particularly sunny day should not be used by itself to estimate annual output.

Solar generation vs. electricity consumption

Solar energy production and electricity consumption are related, but they are not the same thing. Solar generation is the electricity generated by your solar system.

Electricity consumption is the electricity used in your home or business.  For example, suppose your solar system produces:

650 kWh per month

When your property is used:

800 kWh per month

Your solar energy is less than your total monthly electricity consumption. The timing of electricity use also matters. A property may use significant electricity at night when the solar panels are no longer producing. If you want to determine the solar capacity required for your electricity consumption, use our solar size calculator.

Solar generation vs. electricity savings

Solar energy production is measured in kWh , while financial savings depend on the monetary value of these units. The value of electricity used directly on your property may be different from the electricity exported to the grid.

So your final savings may depend on:

•  Electricity tariff
•  Daytime electricity consumption
•  Grid imports
•  Solar Export
•  Applicable billing rules

Use a solar savings calculator when you want to estimate the financial value of solar production. For grid import and export calculations, use the Net Metering Calculator .

What is not included in this solar production calculator?

This calculator focuses on straightforward estimation of solar power generation.

It does not calculate individually:

•  Accurate historical weather for your address
•  Satellite radiation data
•  Roof azimuth
•  Panel tilt
•  Detailed shading
•  Individual solar panel models
•  Inverter trimming
•  Hourly electricity consumption
•  Disadvantages of battery charging
•  Battery discharge damage
•  Long-term solar panel degradation
•  Exact equipment shutdown time

For detailed system design, use site-specific solar resource data along with a professional assessment of the property and equipment.

Who should use the Solar Production Calculator?

This calculator can help:

•  Homeowners are considering rooftop solar power.
•  Current solar customers compare expected generation.
•  Solar production estimating businesses
•  Buyers comparing different sizes of solar systems
•  Students are learning basic solar calculations.
•  Anyone who wants to estimate daily, monthly or annual solar production.