How Many Solar Panels Do You Need to Run a House in Pakistan?

The question almost every Pakistani household asks is "how many panels do I need?" The more useful question is "how many units do I use, and when do I use them?" Answer the second and the first becomes arithmetic.

Here is the method a competent installer should walk you through — and which you can do yourself in ten minutes with a year of bills.

Step 1: Find your real consumption

Collect twelve months of electricity bills and write down the units consumed each month. Twelve is important: Pakistani households have a severe summer peak, and sizing from a single winter bill guarantees an undersized system while sizing from a single July bill guarantees an oversized one.

Add the twelve figures and divide by twelve. That average monthly consumption is your anchor number.

Step 2: Convert units into kilowatts of solar

Pakistan has genuinely good solar resource across most of the country. As a planning assumption, one kilowatt of properly installed, unshaded solar generates about 4 to 4.5 units per day averaged across the year — roughly 120 to 135 units per month.

So:

• 350 units/month → approximately 2.5 to 3 kW
• 600 units/month → approximately 4.5 to 5 kW
• 900 units/month → approximately 7 to 7.5 kW
• 1,200 units/month → approximately 9 to 10 kW

At today's module wattages — commonly 550 to 600 watts per panel — a 5 kW array is about nine or ten panels. That count will keep falling as module wattage rises, which is exactly why comparing vendors on panel quantity is misleading.

Step 3: Check the three things that override your arithmetic

Sanctioned load. Your connection has an approved capacity, and it effectively caps what you may install under net metering regardless of roof space or budget. Check it on your bill before you fall in love with a system size.

Usable roof area. As a rough guide, allow about 90 to 100 square feet of unshaded roof per kilowatt once walkways and tilt spacing are included. A 10 kW ambition on a roof with 600 usable square feet is not a quotation problem, it is a geometry problem.

Shading. A water tank, parapet, stairwell or neighbouring building that shades part of the array for two hours a day costs far more generation than most buyers expect, because shading on one module can drag down a whole string unless the system is designed for it.

Step 4: The step almost everyone skips — when do you use power?

This determines whether your system performs well or merely exists.

Under net metering, a unit consumed as it is generated offsets your full retail tariff. A unit exported earns the lower buyback rate. Two identical 5 kW systems on two identical roofs can deliver very different savings purely because of when the households use electricity.

• A home with someone present during the day, running air conditioning from noon, captures most of its generation at full value.
• A home that is empty from 9am to 6pm exports most of its generation at the lower rate and buys back its evening consumption at the higher one.

The fix is rarely more panels. It is:

• Shifting flexible loads — washing machines, irons, water pumps, pool pumps, dishwashers — into daylight hours.
• Pre-cooling the house in the afternoon rather than fighting the heat at 9pm.
• Or adding storage, which is a separate investment with separate maths — see the battery storage desk.

Worked example

A household in Lahore averages 720 units a month across the year.

• Target capacity: 720 ÷ 130 ≈ 5.5 kW
• Panels at 580 W: 5,500 ÷ 580 ≈ 10 panels
• Roof needed: roughly 500 to 550 square feet unshaded
• Sanctioned load: must be checked — if it is below the system size, that is the binding constraint

If that household is empty on weekdays, a 4 kW system sized to its daytime base load plus deliberate load-shifting may well produce better financial returns than the full 5.5 kW, because a higher share of every generated unit is consumed at full retail value.

What a good proposal should contain

Any installer quoting you a system size should be able to hand over, in writing:

• Your twelve-month consumption data and the average used for sizing.
• The assumed daily generation per kilowatt and where that assumption comes from.
• Assumed system losses, soiling and annual degradation.
• Roof layout showing panel placement and any shading analysis.
• Confirmation that the proposed size is within your sanctioned load.

A proposal without these is a price, not a design.

The bottom line

Size from your bill, not your appliances. Use 120 to 135 units per kilowatt per month as your planning figure. Check sanctioned load, roof area and shading before committing — and pay as much attention to *when* you consume electricity as to how much.

Get sizing right before you spend

A badly sized system is the most expensive mistake in Pakistani rooftop solar — and it is almost always avoidable with better information.

• Read our continuing Pakistan energy coverage on net metering, tariffs and equipment.
• Explore the solar energy desk for practical guidance and project economics.
• Subscribe to The Energy Edit — free, independent, no paywall. Start here.

Installers and equipment suppliers: reach buyers at the moment they are sizing a system. Partner with Arcnex Energy.