Want to Install a Rooftop Solar System on Your Home? Here’s What You Should Know

This is the first of a series of articles that will tell you everything you need to know about installing a rooftop solar system on your home

October 9, 2020


Solar energy is the most flexible form of renewable energy and has become affordable enough for most households. As solar costs keep dropping, the process of installing solar, what to know, where to start, whom to call, and what to pay is not so simple.

Mercom has been receiving a flood of inquiries for rooftop solar installations from residential customers who want to know how to install and whom to talk to. This reiterates our view that the lack of awareness among the consumers is one of the primary reasons for rooftop installations not gaining momentum in the residential space.

While the COVID pandemic has affected consumers’ finances over the past six months, interest and adoption of solar among residential customers in India have always been weak when compared to other countries.

For a homeowner, information on rooftop suppliers, costs, government policies, subsidies, and procedures are hard to come by.

The ideal roof for your solar system

The most important part of a rooftop solar installation is the quality of the roof.

A critical factor is the age of the roofing structure and the wear and tear it has endured. If repairs are needed, then they should be taken care of before a solar system is installed. The roof should be capable of holding installations securely.

Shaili Yadav, Business Head at HomeScape– a residential solar installer by Amplus Solar, says, “The installation itself isn’t heavy to cause any damage to the rooftop; however, strong winds can adversely affect installations. Therefore, the roof must hold the installation when winds are blowing at high speed.”

The other key feature concerns sunlight. It needs to be available 365 days of the year, in an ideal situation. In other words, the roof must not be shadowed by any large objects like the trees, adjacent roofs, or buildings.

Ramesh Shivanna, Director at Sadbhavana Energy, says that typically a 100 sqft shadow-free roof is required to install a 1 kW rooftop solar system.

It is necessary to factor in the type of rooftop and its orientation before installing solar systems. Slanting rooftops are optimal for installing solar modules, especially when the slope is towards the south. Since India falls in the northern hemisphere, south-facing rooftop solar systems will receive the most sunlight.

In the case of flat rooftops, modules should be installed at an angle facing south.

What should the size of your rooftop solar system be?

The ideal size of a rooftop solar installation for an average home can be anywhere from 1 kW to 10 kW. The ideal roof area available and the capacity allowed by the power distribution companies for installation will determine the size of the rooftop solar system that can be installed.

Typically, electricity charges in any home depend on factors such as the total area of the house, appliances used, and hours of usage, among other factors.

For example, in Bangalore, a two-bedroom house with 8-9 lights of 40 Watts (W) each, 6-7 ceiling fans, 2-3 water heaters, and two air conditioners will attract a monthly electricity bill of approximately  ₹2,000-3,000 ($27-41) considering an average electricity tariff of ₹5.50 per unit (kWh). The usage and the corresponding bills will vary based on the utilization of these gadgets. The bill will be considerably higher in summer when the air conditioners are running through the night. These homes will generally have a 6-7 kW of power capacity utilization permission from the power distribution company.

According to Yadav, on an average, a 5 kW system is installed on domestic rooftops. The efficiency of the installation depends on the efficiency of the solar panel. If the panel is rated 330 W, then a 5 kW system would require about 15 solar panels.

“We ask for the electricity bills from customers. For instance, consider someone consuming a certain number of units, which translates to ₹15,000 ($203) in power bills. We divide the bill amount with the power distribution company’s tariff, which is in the range of ₹5-6 (~$0.06)/unit, and it works out to around 2,500-3,000 units of power consumed in a month.”

These rooftop solar systems are connected to the grid, which means the electricity produced from the rooftop solar system is supplied to the distribution company, monitored through the net metering system when available.

The power produced by a rooftop solar system does not mean that you are no longer dependent on the grid. It only means that you are generating clean energy to compensate for the power you were using from the DISCOMs and reducing your power bills at the same time. The money you invest in the rooftop solar system will be made up for by saving on the electricity bills.

How long will my rooftop solar system last?

Mercom spoke with the founder and CEO of U-Solar Clean Energy, K. R. Harinarayan, who said, “A rooftop solar system will generate clean energy for approximately 25 years. The solar system’s maintenance is important for its longevity, and it is essential to procure the best products.”

Once the system crosses its useful lifetime, you can either re-invest in the project by replacing or upgrading the products, including solar panels and inverters, or recycle the components.

According to Mercom’s Q2 2020 India Solar Market Update, India’s average rooftop solar project cost has been consistently dropping. The drop in small rooftop solar installation costs is primarily due to the falling prices of solar panels.

Our upcoming articles will try and answer questions like cost, savings, and other important information vital in installing a residential rooftop solar system.

Contact us by filling out this form if you are planning to install a rooftop solar system for your home.


Image credit: By U.S. Department of Energy from United States – Children of the Sun Solar Initiative, Public Domain