What Size Solar System Do I Need? Pakistan Guide 2026
The most expensive solar system is the wrong-sized one. Oversize it, and under the new NEPRA net billing rules, you are exporting surplus units at a fraction of what you pay for them. Undersize it, and you are still writing cheques to the utility every month for no reason.
Right-sizing a solar system is engineering. It is not guessing. It is not copying your neighbor. It is math, applied to your specific consumption pattern, your roof, and your city.
This guide walks you through the exact process.
Step 1: Read Your Electricity Bill
Every sizing calculation starts with one number: your monthly electricity consumption in units (kWh). You will find this on your WAPDA, K-Electric, LESCO, IESCO, or MEPCO bill, listed as “units consumed” or “kWh.”
Do not use a single month. Pull your bills from the last six months minimum. Ideally twelve. Your consumption in July is nothing like your consumption in January. Air conditioning alone can double or triple a household’s load in summer.
What to look for
• Units consumed: The raw number. This is what you are trying to offset with solar.
• Peak summer months: Usually May through September. This is your highest consumption period.
• Winter baseline: November through February. This is your floor.
• Average: Add all months, divide by the number of months. This is the number you will use for sizing.
If your average monthly consumption is 1,000 units but your summer peak hits 1,600, you need to decide: do you size for the average and accept some summer bills, or size closer to the peak and have surplus in winter? Under net billing, oversizing has a real cost. Size for the average unless you have specific reasons not to.
Step 2: The Sizing Formula
In Pakistan, a well-installed 1kW solar system generates approximately 130 units (kWh) per month on average, accounting for seasonal variation, panel temperature losses, inverter efficiency, and dust.
The formula is simple:
Monthly units consumed ÷ 130 = system size in kW
Example: 1,000 units per month ÷ 130 = 7.7kW. You would install an 8kW system.
Quick Reference Table
| Monthly Units (kWh) | Recommended System Size |
|---|---|
| 300 | 3 kW |
| 500 | 4-5 kW |
| 800 | 6-7 kW |
| 1,000 | 7-8 kW |
| 1,500 | 10-12 kW |
| 2,000+ | 15 kW+ |
These are starting points. Your actual size depends on your city, roof orientation, shading, and whether you choose on-grid or hybrid.
Step 3: Adjust for Your City
The 130 units per kW figure is a national average. Actual generation depends on peak sun hours, which vary by city. More sun hours means more generation per kW, which means you can install a slightly smaller system for the same offset.
| City | Average Peak Sun Hours | Notes |
|---|---|---|
| Karachi | ~5.5 hours | Consistent year-round. Coastal humidity causes minor soiling. |
| Lahore | ~5.0 hours | Winter smog reduces generation in Dec-Jan. Plan for it. |
| Islamabad | ~5.2 hours | Rain keeps panels clean. Moderate seasonal swing. |
| Multan / Faisalabad | ~5.5 hours | Excellent solar resource. Among the best in Pakistan. |
| Peshawar | ~5.0 hours | Similar to Lahore. Winter dip is noticeable. |
If you are in Lahore or Peshawar, consider adding 5-10% to your calculated system size to compensate for lower winter output. If you are in Multan or Karachi, the base formula works well as-is.
On-Grid vs Hybrid: Different Sizing Logic
Your system type changes the sizing equation.
On-grid (net metering / net billing)
An on-grid system feeds excess power to the grid during the day and draws from the grid at night. You only benefit from solar during daylight hours. Size it to match your daytime load, not your total consumption. If 60% of your usage happens during the day (common for homes with stay-at-home occupants or work-from-home setups), size for that 60%.
Hybrid (with battery storage)
A hybrid system stores surplus daytime generation in batteries for evening and nighttime use. This means you can offset a larger share of your total bill. Size the panels to cover your full daily consumption, and size the battery bank to cover your evening load — typically 4-6 hours of usage after sunset.
Hybrid systems cost more upfront. But under the current net billing rates, where export credits are low, storing your own power and using it at night often makes better financial sense than sending it to the grid.
Roof Space: Do You Have Enough?
A modern 550W-585W solar panel occupies roughly 30-32 square feet. For every 1kW of system capacity, you need approximately 60-70 square feet of unshaded roof space.
Practical estimates:
• 5kW system: ~320 sq ft
• 8kW system: ~520 sq ft
• 10kW system: ~650 sq ft
• 15kW system: ~1,000 sq ft
This includes spacing between rows for airflow and to prevent inter-row shading. Do not let anyone calculate based on panel area alone. You need access paths for maintenance and clearance from rooftop structures — water tanks, parapets, satellite dishes.
If your roof is tight, higher-efficiency panels (22%+ with N-type TOPCon cells) produce more watts per square foot. They cost slightly more per panel but can be the difference between fitting a system and not fitting one.
Common Sizing Mistakes
We see these regularly. All of them cost homeowners money.
• Copying your neighbor’s system. Your consumption pattern is not the same. Your roof orientation is not the same. Your shading profile is not the same. Their 10kW system might be your 7kW system, or your 12kW system.
• Using one month’s bill. A single summer bill overstates your annual average. A single winter bill understates it. Use six to twelve months of data.
• Ignoring future load growth. Planning to add another AC unit next year? Thinking about an electric vehicle in three years? Factor it in now. Adding panels later is more expensive per kW than doing it right the first time.
• Oversizing under net billing. The old net metering rules credited exports at near-retail rates. The new NEPRA net billing framework does not. Every excess unit you export earns significantly less than the unit you self-consume. Right-sizing is now more financially critical than ever.
• Forgetting about inverter clipping. If your installer pairs a 10kW panel array with a 7kW inverter to save costs, you will lose generation at peak hours. The inverter must be matched correctly to the array size.
How Solar Citizen Sizes Your System
We do not use a generic calculator. Every Solar Citizen system goes through a proper engineering assessment.
• Load profiling: We analyze your actual electricity bills — monthly consumption, peak demand, time-of-use patterns. Not estimates. Actuals.
• Aerial roof survey: We assess your roof area, orientation, tilt, and shading from nearby structures or trees. Shadow analysis is done for both summer and winter sun angles.
• SOL AI benchmarking: Our SOL AI monitoring platform has real generation data from hundreds of installed systems across Pakistan. We know exactly how much a system produces in your neighborhood, on your type of roof, in your city. That data makes our sizing precise.
• Future-proofing: We discuss your planned load additions and design the system and inverter capacity to accommodate growth without a complete retrofit.
The result is a system that generates what you need. Not more, not less. No wasted panels. No surprise bills.
If you want a system sized by engineers using real data, not a salesman using a rule of thumb, request a free assessment from our team.