How to Calculate your Solar system requirement?

Written by Rohit Grover
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Learn to calculate the right size of the rooftop solar system for your home.

Two important factors which will play a role in this calculation are:

  1. Your Annual Electricity Consumption

  2. Shadow-free area on your roof

Once you know these 02 things. Follow these steps to calculate the system requirement for your house.


Step 1: Check your annual unit consumption on the electricity bill.

Step 2: Choose how much electricity bill you want to reduce based on the area of your rooftop.

Step 3: Calculate the system requirement to reduce your electricity by up to 100%

Let me walk you through an example: If you consume 12000 units per year.

And you want to reduce your bill up to 100%.

Divide 12000 by 365

12000/365 = 32 units per day (approximately).

1. Zero Bill (100% electricity bill)

To get a zero bill, you need to produce 32 units per day through solar.

4 units/day is produced by 1kWP plant.

To produce 32units/day, you need a 8kWP plant.

You will need a 8kWP plant and 800 sq. feet area to reduce your bill by 100%.

2. 50% electricity bill

To reduce your bill by 50%, you need to produce 16 units per day through solar.

4 units/day is produced by a 1kWP plant.

To produce 16units/day, you need a 4kWP plant.

You will need a 4kWP plant and 400 sq. feet area to reduce your bill by 50%.

3. 25% electricity bill

To reduce your bill by 25%, you need to produce 16 units per day through solar.

4 units/day is produced by a 1kWP plant.

To produce 8units/day, you need a 2kWP plant.

You will need a 2kWP plant and 200 sq. feet area to reduce your bill by 25%.


As you can see in the above example, you can save up to 100% on your electricity bills with a solar rooftop system. Now, you can calculate your own system requirement based on the area of your rooftop and desired savings.

In case, you have other concerns in sizing the system, please Schedule a Call. We’d be happy to help.

You can calculate your solar system requirement right here. 👉 Solar Calculator