How many solar panels does my home need? A guide for Tricity

The number of panels on your roof follows from two figures: the size of the system you need, in kW, and the wattage of each panel. Once those are known, the arithmetic takes a minute. This guide shows how to do it, how much roof the panels need, and what typical homes in Mohali, Zirakpur and Kharar end up with.

Step 1: Know your system size

The size comes from your electricity use, not from the number of rooms. In Tricity, each kW of panels makes roughly 110 to 125 units a month, so a home that needs to cover about 550 units in its peak summer month needs around 5 kW. In Punjab, the 300 free units change the answer, because the aim is usually to keep your peak month within the free limit rather than to cover every unit. Our guide to what size system your home needs works through it, and the savings calculator does it from one bill.

Step 2: Divide by the panel wattage

Most home panels sold in 2026 are rated between about 540 and 600 watts. Divide the system size in watts by the panel wattage, and round up:

Number of panels = system size in watts ÷ panel wattage

For a 5 kW system with 550 W panels: 5,000 ÷ 550 = 9.1, so 10 panels.

Rounding up means the system ends up slightly larger than the round figure: ten 550 W panels make 5.5 kWp. System size in a quotation should always be the total panel capacity in kWp, so check that panels × wattage matches the size you are quoted. The final count can also shift by one panel, because the panels are wired into the inverter in groups that have to suit its voltage range.

Typical homes in Tricity

These are rough guides for general-category homes on PSPCL, sized to keep the peak summer month within the free units. Your own bills decide the real figure.

Our guide to solar for one or two ACs explains why two ACs usually need 5 to 6 kW rather than exactly 5.

How much roof the panels take

A typical 550 W panel measures about 2.3 m by 1.1 m, roughly 28 sq ft, and weighs 25 to 30 kg. The panels alone for 1 kW cover about 50 sq ft. The rule of thumb of 80 to 100 sq ft per kW allows for the gaps between rows, so that one row does not shade the next, and for walkways to reach the panels for cleaning.

How much of your roof is usable depends on:

• Shadows from water tanks, stair rooms, parapets, trees and taller buildings next door, which are longest on winter mornings
• The tilt. Steeper panels need wider gaps between rows. Our tilt angle guide has a table of row spacing for each angle
• The structure. A raised structure can sit over a water tank’s base or a seating area, which often frees more roof than a low frame

When the roof is smaller than the system

If the roof cannot hold the panels your bill calls for, there are four options:

1. Higher-efficiency panels. Newer panel types, such as TOPCon, fit more watts into the same area.
2. A raised structure over obstacles, so the area around a water tank or stair room can carry panels.
3. Accept a smaller system. In Punjab, a system that brings your peak month close to the free limit still removes most of the bill.
4. A lower tilt, which fits more rows on a shallow roof at the cost of a percent or two of output.

Does the number of panels affect the subsidy?

The PM Surya Ghar subsidy depends on the system’s capacity in kW, not on the number of panels. It reaches its maximum of ₹78,000 at 3 kW, so a 3 kW system must have at least 3,000 watts of panels, for example six 550 W panels. The panels must also be DCR, made with Indian cells.

Common questions

How many solar panels does a 3 BHK house need?

A 3 BHK home in Tricity with two air conditioners typically needs 5 to 6 kW, which is 10 or 11 panels of 550 W. A 3 BHK with one AC may need only 3 to 4 kW, or 6 to 8 panels. Your summer bills decide the exact figure.

How many panels make a 5 kW system?

Ten panels of 550 W (5.5 kWp) or nine panels of 600 W (5.4 kWp). Quotations should show the panel count and wattage so that you can check the total capacity.

How much roof does a 5 kW solar system need?

About 400 to 500 sq ft of shade-free roof, including the gaps between rows and room to reach the panels for cleaning. A raised structure can make more of the roof usable around water tanks and stair rooms.

Is it better to have more lower-wattage panels or fewer higher-wattage ones?

For the same total capacity, output is much the same. Higher-wattage panels need fewer mounting points and less roof, which helps on a small roof. On a large unshaded roof, the cheapest price per watt usually wins.