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:

  1. Monthly Electricity usage in KWh/MWh

  2. Monthly Peak Sun Hours

  3. 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.

Let’s take Waaree’s 540Wp Bifacial module for our calculations.

This was the last piece needed for our formula to know ‘how many solar panels we will need to generate 100MWh per month of electricity.’

Let’s assume that the PSH is 5.2 at your site location, now multiply it by the number of days in a month say 31 to get a monthly amount of 161.2.

100000KWh/161.2 = 620.34 * 1000 = 620340

Solar Panels Needed for 100MWh per Month

620340/540 = 1148.7 ~ 1149

You are going to need 1149 540 Wp Waaree solar panels for this site.

What Are The Types Of Solar Modules Available?

  • BIPVBuilding Integrated Photovoltaic (BIPV) systems integrate Solar Modules into the building structure, such as the roof or facade, adding architectural appeal.

  • BifacialBifacial solar modules differ from conventional modules in that they have solar cells on both sides. This mechanism helps the solar panel absorb the sun's energy from both sides, increasing energy consumption. Placing the double-sided panel on a light transmissive material (such as a white TPO blanket or a floor with light-colored rocks) will generate additional power from the backside.

  • MonoWaaree's monocrystalline panels use very high crystalline silicon and are manufactured under strict manufacturing standards. For an extended period of time, our solar panels consistently deliver reliable power and more kWh energy.

  • Poly – As polycrystalline solar panels do not require individual shaping and placement of each crystal, they are more eco-friendly than monocrystalline panels, which have a lower heat tolerance. So, at higher temperatures, these solar panels have lower efficiency than others with high power density.

  • Flexible – Waaree's semi-flexible solar panels are sleek, long-lasting, and nearly indestructible. In addition to providing a charging option for high-capacity batteries, these solar panels adhere to nearly any surface. Modules are available in a variety of configurations for permanent and semi-permanent installation.

How Waaree RTL can Help?

WAAREE RTL (WRTL) is Waaree Energies’ EPC arm which is also a listed company in India. It has an experience of more than 600MWp of Solar power plant installations across several countries including projects like ‘50MW in 100 Days – Vietnam, while embarking on a successful competence in Ground mounted, Rooftop, and Floating Solar power projects. WRTL has helped numerous clients with their transition to clean energy and helped reduce their carbon footprint with SOLAR POWER. Step on to your cleaner journey by contacting us at 18002121321 or mail us at

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