There are a lot of talks about Solar power plants these days and one of the most asked questions from the end users is ‘how many solar panels do I need to generate XYZ KWh/MWh per month.’

_* ? = XYZ KWh/MWh

It is paramount to understand three crucial factors while answering this, first is the power rating of the solar panels, second is the irradiation at the location you live and third is your electricity usage. This formula below is applied correctly in order to calculate the number of solar panels needed at any location.

calculate the number of solar panels

In order to calculate, let us understand the input values which are:

Monthly Electricity usage in KWh/MWh
Monthly Peak Sun Hours
Power Rating of Solar Panels

Step 1:

Check your monthly electricity bill usage in Units (Kwh/Mwh) In general you can see your electricity bill for your average kilowatt-hour (Unit) usage for every month:

As we already know here that the power consumption is 100MWh per month here, we will use this number for our further calculations.

Step 2:

Now we need to calculate the peak sun hour at the site location. In order to do that, let us know more about PSH (Peak Sun hours).

1 peak sun hour = 1000W/m2 or 1kW/m2 of sunlight per hour

The peak sun hours are not between sunrise and sunset. These figures represent the amount of solar insolation a specific area would receive when the sun's intensity is highest. Insolation refers to the amount of solar radiation that falls on the earth's surface over time.

Now that we know what maximum sunshine duration stands for, let's see how it's used to measure sunlight for a given location.

As we all know, the sun doesn't shine all day at its maximum hours. Instead, the intensity of sunlight hitting the panels constantly fluctuates depending on the time of day and weather.

Early morning and late afternoon solar radiation is expected to be less than 500 W/m². Conversely, under ideal conditions at noon on a sunny day, you can actually get more than 1000 W/m², say 1100 W/m² or more.

Don't worry. These quantities can be easily expressed in terms of solar peak hours. Example:

One hour in the morning with 500 W/m² average sunlight corresponds to 0.5 hours of peak sunshine.

Noon with average solar irradiation of 1,100 W/m² corresponds to 1.1 peak hours of sunshine.

While this may sound complicated, the concept is actually relatively easy to apply. For example, if a particular location receives a total of 6,650 Wh/m² of solar radiation during the day, that location will have 6.65 peak sun hours.

As the image shows, summing the total solar radiation for a given location gives the total maximum sunshine hours.

For this reason, the concept of "peak hours of the sun" was developed. It can accurately measure the amount of radiation (sunlight) that hits a solar panel installed at a specific location. This allows you to calculate the expected energy production of a particular-size solar system installed at that location.

In other words, the peak hours of sunshine indicate how much power the roof solar array is producing. You can also compare the availability of sunlight at different locations.

A home's solar potential can be gauged by your region's average peak sun hours. The following example shows how peak sun hours can be used to calculate how much electricity your solar panel system needs to produce:

7 hours of peak sun
The electricity you used last year was 25,000 kWh
It takes 68.49 kWh per day to burn 25,000 kWh over 365 days
9.78 kWh per day x 68.49 kWh per day / 7 peak sun hours per day
The solar PV system you should install should be 10kW

You can also calculate PSH through Online calculators as mentioned below:

PSH through Online calculators

Step 3: Know the power rating of Solar Panels>

As we are calculating for the MW level capacity of the power plant, Power generators should look for the maximum possible wattage for a solar panel in order to reduce the land requirement.