How to Size a Solar System for Your Home in Pakistan

The single biggest mistake Pakistani households make when going solar is picking a system size based on a neighbour's recommendation or a salesperson's suggestion rather than their own actual electricity consumption. A system that is too small leaves you still paying large grid bills in summer. A system that is too large costs more than it should and takes longer to pay back. Sizing correctly starts with one number: your monthly units consumed.

Step 1 — Find Your Monthly Units from Your Electricity Bill

Open your duplicate bill on BijliBillCheck.pk and look for the 'Units Consumed' figure. This is the kilowatt-hours (kWh) your household used in that billing period. Because consumption varies by season, collect three to four bills — at least one winter bill and one or two summer bills. Your solar system needs to be sized against your peak-month consumption, not the average, because that is when your bill pain is greatest and when solar generation is also at its highest.

A typical Pakistani household breakdown by size: a small flat or modest house with fans, lights, fridge, and no AC uses 150–250 units per month in summer. A mid-size house with one 1.5-ton AC runs 350–550 units. A larger house with two ACs, a water motor, and full lighting can exceed 800–1,000 units in peak summer.

Step 2 — Convert Monthly Units to Required System Size (kW)

In Pakistan, a 1 kW solar panel system generates approximately 110–140 kWh per month under typical conditions (south-facing roof, good irradiance, minimal shading). This translates to a simple sizing formula:

• Monthly units needed ÷ 120 (conservative average output per kW) = system size in kW
• Example: 400 units ÷ 120 = 3.3 kW → round up to a 3.5 or 4 kW system
• Example: 700 units ÷ 120 = 5.8 kW → a 6 kW system covers this comfortably
• Example: 1,000 units ÷ 120 = 8.3 kW → an 8–10 kW system with a load sanction check first
• Add 10–15% buffer for panel degradation, dust, and shading losses

Step 3 — Check Your Sanctioned Load Limit

NEPRA's net metering regulations cap your solar system size at your connection's sanctioned load. If your DISCO connection has a sanctioned load of 5 kW and you want to install a 7 kW system, you must apply for a sanctioned load increase first — otherwise your net metering application will be rejected. Your sanctioned load is printed on your electricity bill, usually in the consumer detail section as 'Sanctioned Load' or 'Contract Demand' in kW or kVA.

For most domestic single-phase connections the sanctioned load is 5–10 kW, which is sufficient for systems that cover typical household consumption. Three-phase connections can carry higher loads and support larger systems. If your calculated system size exceeds your current sanctioned load, ask your installer to handle the load enhancement application to your DISCO before submitting the net metering paperwork.

Step 4 — Decide Between On-Grid, Hybrid, and Off-Grid

System type determines cost more than panel count does. An on-grid (grid-tied) system with net metering is the cheapest option — it uses the grid as a virtual battery during the day (exporting surplus) and draws back at night. A hybrid system adds a battery bank for backup during load shedding, costing 40–70% more but providing power during outages. A fully off-grid system has no grid connection at all and requires a large battery bank to cover nighttime — the most expensive option and rarely cost-effective in areas with a functional grid.

For most Pakistani urban and semi-urban households, a hybrid system — on-grid during the day with a small battery for evening essentials — strikes the best balance of cost, backup, and bill reduction. The battery covers fans, lights, and a router through a 4–6 hour load shedding window without the expense of a full off-grid setup.

Step 5 — Estimate Cost and Payback Period

Solar system prices in Pakistan fluctuate with exchange rates and panel import duties, but rough benchmarks for 2026 are: a 3 kW on-grid system costs approximately Rs. 450,000–600,000; a 5 kW on-grid system Rs. 700,000–900,000; a 5 kW hybrid with a 5 kWh battery bank Rs. 1,100,000–1,400,000. Prices vary significantly by panel brand, inverter quality, and installer. Always get three quotes from NEPRA-licensed installers.

Payback calculation: divide total system cost by your monthly bill saving. A household saving Rs. 18,000 per month on a Rs. 900,000 system pays back in 50 months (just over four years). After payback, the system generates free electricity for 20+ years. The higher your current bill, the faster the payback — households paying Rs. 25,000–40,000 per month in summer often see payback in under three years.