Solar System Size Estimator

Instant · no signup needed

Estimate the solar system size (in kW) and approximate number of panels needed to cover your electricity usage, based on your average monthly units from your electricity bill.

Electricity usage

Average monthly units (kWh, from your bill)

Panel wattage

Estimated system size0 kW

Approx. panels needed0

Uses Pakistan's average of 4.5 peak sun hours per day and an 80% system-loss allowance (inverter, wiring, dust, temperature). A general planning estimate only — actual system design depends on roof space and orientation, shading, backup/battery needs, and your real load profile. Get a site survey from a solar installer before buying.

Prefer a real answer, not a calculator?

Book a free site visit

Tell us your preferred date and time, and we'll confirm a slot to visit your plot or discuss your project in person — no obligation.

Worked Lahore Example: Sizing a Solar Array for 750 Monthly Units

Net metering solar calculation

For example, take a 10 Marla double-storey household in Lahore that uses 750 kWh (units) per month during peak summer months, driven by two 1.5-ton inverter air conditioners, an inverter refrigerator, kitchen appliances, and water pumping. Entering 750 units into our solar calculation model with the calculator's default 550W panels gives:

Engine Sizing Output (750 Units Monthly):

Average Daily Generation Needed: 25.0 kWh/day (750 units ÷ 30 days)
Required Inverter System Capacity: 6.94 kW (factoring 4.5 peak sun hours and 80% combined system derating)
Solar Panels Required: 13 panels of 550 Watts each (6,944 W ÷ 550 W = 12.6, rounded up)

Roof Layout & LESCO Net Metering:

Each 550W panel measures approximately 7.5 × 3.75 ft (28 sq ft). Thirteen panels require ~364 sq ft of shadow-free rooftop space facing true South at a 30-degree tilt angle. In Lahore, pairing this 7 kW solar array with an on-grid hybrid inverter and applying for a LESCO green bi-directional net meter offsets monthly billing during high peak-hour tariff bands.

Frequently asked questions

What assumptions does this calculator use?+

It uses Pakistan's average of 4.5 peak sun hours per day and an 80% system-loss allowance to account for inverter efficiency, wiring losses, dust, and temperature effects on panel output.

Is this enough to design my actual solar system?+

No — this is a general planning estimate only. Actual system design depends on your roof space and orientation, shading, whether you want battery backup, and your real load profile. Get a site survey from a solar installer before buying equipment.