Solar power is a rapidly growing renewable energy option that offers numerous advantages. To make the most of it, it is crucial to understand how to calculate solar panel kWh. In this post, we will learn about the solar power calculator to estimate PV production.

How to Calculate Solar Panel kWh

The calculation of solar panel kWh is dependent on several parameters that affect overall power generation. The output of a solar panel is commonly measured in watts (W), which represents the theoretical power production under perfect conditions. Manufacturers provide wattage ratings for solar panels, but real-world conditions may result in lesser output. To calculate the daily kWh generated by solar panels, use the following steps:

1. Determine the Size of One Solar Panel

Multiply the size of one solar panel in square meters by 1,000 to convert it to square centimeters.

Example: If a solar panel is 1.6 square meters, the calculation would be 1.6 ×— 1,000 = 1,600 square centimeters.

2. Consider the Efficiency of One Solar Panel

Multiply the converted size by the efficiency of one solar panel, represented as a decimal.

Example: If the panel’s efficiency is 20%, (it means 20% of the total wattage) the calculation would be 1,600 ×— 0.2 = 320 W.

3. Consider Sun Hours

Multiply the efficiency-adjusted size by the number of sun hours in your area per day.

Example: If your area receives 4.5 sun hours, the calculation would be 320 ×— 4.5 = 1,440 Wh.

4. Convert to kWh

Divide the result by 1,000 to convert watt-hours to kilowatt-hours (kWh).

Example: 1,440 ×· 1,000 = 1.44 kWh per day.

Moreover, to estimate the monthly solar panel output, multiply the daily kWh by the number of days in a month:

Example: If the daily output is 1.44 kWh, the monthly output would be 1.44 ×— 30 = 43.2 kWh per month.

5. Output Per Square Meter of Solar Panels

Calculating the output per square meter can be useful for comparing different solar panel systems. In this solar power calculator kWh, to determine this value, use the following formula:

  • Multiply the number of panels by the capacity of the solar panel system.
  • Divide the capacity by the total size of the system (number of panels ×— size of one panel).


Consider a system with 16 panels, where each panel is approximately 1.6 square meters and rated to produce 265 watts.

Calculation: 16 ×— 265 = 4,240 kW (total capacity)

Now, total size = 16 ×— 1.6 m² = 25.6 m²

Therefore, output per square meter, total capacity ×· total size = 4,240 ×· 25. 6 = 165 W per square meter.

By considering these calculations and the factors affecting solar panel output, you must accurately know how to calculate solar panel kWh generated by your solar panel system. This estimation provides valuable insights into energy production and helps you make informed decisions about your solar energy needs. However, understanding environmental factors, panel efficiency, and the number of sun hours in your area are all important concerns that must be taken into account when effectively estimating the energy generation of your solar panels.

Also See: How to Calculate Inverter Battery Backup Time

How many kWh Per Day Your Solar Panel will Generate?

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The daily kWh generation of a solar panel can be calculated using the following formula:

The power rating of the solar panel in watts ×— Average hours of direct sunlight = Daily watt-hours.

Consider a solar panel with a power output of 300 watts and six hours of direct sunlight per day. The formula is as follows:

300W ×— 6 = 1800 watt-hours or 1.8 kWh.

Using this solar power calculator kWh formula, you can determine energy production on a weekly, monthly, or yearly basis by multiplying the daily watt-hours by the respective periods. It is critical to evaluate and consider the number of peak sunlight hours in your specific geographical area when estimating the energy generation of your solar panels. Seeking professional assistance often provides estimated exposure tables based on local conditions to optimize panel placement.

Also Read: How to Calculate Battery Capacity for Solar System?

How many kWh Per Month Your Solar Panel will Generate?

To determine the monthly kWh generation of a solar panel, several factors need to be considered. For example, a 400W solar panel receiving 4.5 peak sun hours each day can generate approximately 1.8 kWh of electricity daily. Multiplying this value by 30 days, we find that such a solar panel can produce around 54 kWh of electricity in a month.

In states with sunnier climates like California, Arizona, and Florida, where the average daily peak sun hours are 5.25 or more, a 400W solar panel can generate 63 kWh or more of electricity per month.

Also See: How to Calculate Solar Panel KWp (KWh Vs. KWp + Meanings)

How many kWh Per Year do Solar Panels Generate?

A 1 kilowatt (1 kW) solar panel system may produce roughly 850 kWh of electricity per year. However, the actual amount of electricity produced is determined by a variety of factors such as roof size and condition, peak solar exposure hours, and the number of panels.

A system with a capacity of roughly 4 to 5 kW is often recommended for larger homes or households with greater energy consumption, capable of generating enough electricity to fulfill the annual energy requirements of a four-to-five-person household.

It’s crucial to realize that energy requirements differ from one home to another. The average American household consumes approximately 10,000 kWh of electricity annually. To meet such needs, a solar panel system with 20 to 30 panels should suffice. However, it’s important to know how to calculate solar panel kWh, since that allows you to evaluate several solar panel systems and select the one that best meets your energy requirements.

Also See: How to Calculate Voc of Solar Panel

What Factors Impact Solar Panel Electricity Generation?

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The factors that impact how much electricity my solar panels generate are as follows:

1. Capacity

Solar panel capacity, often known as peak sun capacity, refers to the maximum quantity of power that may be produced under perfect conditions. It is frequently measured in watts per square meter of panel area. Domestic solar panel setups typically range in capacity from 1 kW to 4 kW. The rated capacity or output is 1,000 watts or 1 kW of sunlight per square meter.

2. Efficiency

The efficiency of solar panels is a measure of how successfully they convert sunlight into electricity. Solar panels are never completely efficient due to different environmental conditions. Most home panels have an efficiency of around 20%, which means they can convert approximately 20% of the solar they receive into useful electricity. Higher efficiency panels with 40% to 50% efficiency are available, although they are typically more expensive, they can save significant roof space.

Also See: 16 Ways to Increase Solar Panel Efficiency

3. Materials

The materials used in solar panels can also have an impact on their efficiency. Monocrystalline panels are the most efficient in terms of production and area utilization since they’re made from higher-grade silicon. Polycrystalline panels, on the other hand, are slightly less efficient but generally more affordable. The materials used in a solar panel system can have an impact on its overall performance and cost-effectiveness.

4. Roof Factors

a) Direction

The facing direction of your roof is crucial for the performance of your solar panels. South-facing roofs offer the best results since they receive the most sunshine exposure. However, solar panels can still be used on east or west-facing roofs, but with significantly reduced efficiency.

b) Angle

The angle at which your roof is inclined also has an impact on the overall effectiveness of solar panels. A roof angle of roughly 30 degrees is frequently thought to be optimal for providing the best balance of solar absorption throughout the year. Adjusting the tilt angle can maximize the energy output of the panels and optimize their efficiency.

Cross-Reference: What Is The Best Angle And Orientation For Solar Panels?

c) Shade

Shadows and obstructions on your roof, such as trees or surrounding buildings, can have a substantial impact on the efficiency of your solar panels. To ensure maximum electricity output, the roof must be clear of any obstacles that may block sunlight and lower panel performance.

5. Location

The amount of sunshine that your property receives is affected by its geographical location. In the United Kingdom, the south of England is generally the sunniest location, owing to high-pressure systems that clear clouds and give adequate sunlight. The amount of sunlight steadily decreases as you approach inland and further north, which can have only a slight impact on the overall productivity of solar panels in those places.

To sum up, calculating solar panel kWh is an important step in evaluating energy output. You can estimate this accurately by considering the parameters such as panel efficiency, solar irradiation, and system losses. This calculation enables you to make informed decisions about your electricity consumption and evaluate the effectiveness of your power system.

Source: How Much Power Does A Solar Panel Produce?


Olivia is committed to green energy and works to help ensure our planet's long-term habitability. She takes part in environmental conservation by recycling and avoiding single-use plastic.

1 Comment

  1. Hello,
    I’m looking to install solar panel on my roof – 2340m2.
    I need to know the power generated plus the cost to install for our internal discussion.
    Appreciate if you can send me the above info.


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