Easy Guide for calculating the size of your Rooftop Solar System

One of the biggest and most common questions before installing rooftop solar is whether rooftop solar will fit properly in the space you have. How much should your system size be? Will it fit within your budget constraints?

The answer to this questions depends on various factors like your current and future energy needs, the shadow free area available on your rooftop and your budget. A few ways to estimate your rooftop system size are given below in this blog. Your solar installer should carry out the technical assessment of your site to give you the exact size of your rooftop solar system based on your needs and constraints.

Your average energy consumption

Check your annual electricity bill to see how many units of electricity you consume on an average every month. The higher your unit consumption, the larger your system size will be.

Here’s an example.

Let us suppose that your average monthly unit consumption is 200 units.

A 1KW solar system typically generates 4 to 5 units a day.

So energy generated in a month is = 4 x 30 days = 120 units

Then system size you need would be 200/120 =1.66 KW (approx 2 KW)

Area available on your roof

This is a very important factor for considering the size of your rooftop system. Check the shadow free space available on your rooftop. Your solar installer will measure this during the site survey and might also recommend you to trim any trees in the surrounding in case they are affecting your available area.

Suppose the shadow-free area on your rooftop is 100 sq ft. The surface area of one panel panels is approximately 20 sq feet.

Hence, the number of panels that will fit is 100/20 = 5 panels

Remember that the number of panels could be less or more depending on the wattage of each panel. Typically a 1 KW system in India needs about 60 sq feet area.

The wattage of the solar panel you choose

For calculating system size, it is important to get to know about wattage of your system. Depending on your budget and rooftop space available, you can choose the wattage of the solar panel.

Generally a single solar panel wattage range is between 50W to 600W. There are three types of solar panels available in the market depending on their efficiency and life. You can choose the right one for your system depending on your budget and energy requirements.

Suppose based on your monthly electricity units, you need a 2KW system.

You choose a 500W panel, then no. of panels will be 2x1000/500 = 4.

Your rooftop should have space available for 4 panels (approx 80 sq feet). If you have more space, you could choose panels of lower wattage and vice versa.

These are some key factors for calculating the size of a solar PV system.

If you are still confused you can get free consultation from us. Frevolt provides you end to end installation service. We will conduct a site assessment and recommend the best system design.

Download our mobile app and install, manage and maintain your rooftop solar with Frevolt.