This free solar system calculator Pakistan tool sizes a rooftop system from your electricity bill. Enter the units (kWh) on your electricity bill and the calculator sizes an on-grid solar system for your city. It gives the kilowatts, panels, roof space and inverter, the estimated cost, how much you would save each month, and the payback period. It uses the 2026 NEPRA net billing export rate by default, which changes the answer a lot.
How to use the Solar System Calculator Pakistan
- Enter your average monthly units (kWh) from your bill and choose your city.
- Choose how much of your usage to cover and the panel wattage.
- Enter the system cost per watt, your grid tariff, the share of solar used directly in the day and the export (buyback) rate.
- Press Calculate to see the system size, panels, cost, monthly saving and payback.
The solar system calculator Pakistan results are only as current as the tariff and buyback rates you enter, so update them when rates change. Tariff and net billing decisions are published by NEPRA.
How the solar size is calculated
As a rule of thumb, 1 kW of solar in Lahore produces about 120–130 units a month on average, more in May–June and less in December–January fog.
Net metering vs net billing in 2026
In February 2026 NEPRA replaced net metering with net billing for new solar consumers. Units you import from the grid are charged at the normal slab tariff, while units you export are bought at a fixed rate of Rs 8.13 per unit. Consumers who already had net metering keep the older rate (about Rs 25.32) until their agreements expire, and new licences run for 5 years instead of 7. Check the latest NEPRA notification and your DISCO (LESCO, IESCO, K-Electric etc.), because the rates can be revised.
Typical system sizes
| Monthly units | Approx. system (Lahore) | Panels (585 W) |
|---|---|---|
| 300 | 2.5–3 kW | 5 |
| 500 | 4–5 kW | 8 |
| 800 | 6.5–7 kW | 12 |
| 1,200 | 10 kW | 17–18 |
Frequently asked questions
How many kW solar system do I need for 500 units per month in Pakistan?
In Lahore or Islamabad, about 4–4.5 kW (around 7–8 panels of 585 W) covers 500 units a month on average. Karachi and Quetta need slightly less because of higher sunshine.
What is the net billing buyback rate in Pakistan?
Under NEPRA’s 2026 rules, new solar consumers are paid Rs 8.13 per exported unit, while imported units are charged at the regular tariff. Existing net-metering users keep the old rate until their contracts end.
Is solar still worth it under net billing?
Usually yes, if you use most of the solar power during the day. Paybacks are longer than under the old net metering. The calculator shows your payback based on your own daytime usage.
How much roof space does a 5 kW system need?
About 25–30 m² (270–320 sq ft) of shade-free roof for nine 585 W panels, including spacing.
How does net billing calculation work?
Under net billing, units you import are charged at your normal tariff, while units you export are credited at a lower buyback rate, instead of being swapped one-for-one as under net metering. Solar you use directly during the day saves the full tariff, so daytime self-use matters more than before.
How do I calculate solar payback in Pakistan?
Payback (years) = system cost ÷ yearly saving. A system costing Rs 750,000 that saves Rs 15,000 a month (Rs 180,000 a year) pays back in about 4.2 years.
Related tools
Estimates only. Solar output, prices, tariffs and NEPRA rules change. Get quotes from AEDB-certified installers and confirm current net billing terms with your DISCO before buying.