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Plot & solar

Rooftop Solar Planner

Size a rooftop solar system from your monthly units: panels, kW, roof space used, generation, savings and payback for Islamabad / Rawalpindi.

System size

8.19 kW

14 × 585 W panels · covers 101% of your use

Generation

908 units / month

10,893 units a year

Roof used

36 m²

of 74 m² roof

Approx. system cost

PKR 941,850(9.4 lac)

Saving per year

PKR 653,601(6.5 lac)

pays back in about 1.4 years

Yield ≈ 1360 units per kW per year for Islamabad/Rawalpindi at a good tilt, less for east/west/north or flat panels. Cost per kW is an indicative September 2026 figure — net-metering rules and tariffs change; ask us for a site survey.

Want exact figures for your plot?

Our team prices real projects in Faisal Hills and the Twin Cities every day.

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The short answer

Solar system size (kW) ≈ yearly electricity use ÷ yearly generation per kW. In the Islamabad–Rawalpindi region a well-tilted, south-facing system generates roughly 1,300–1,400 units per kW per year, so a home using 900 units a month needs about 8 kW — around 14 panels of 585 W.

How the solar planner sizes a system

  1. Yearly use = monthly units × 12.
  2. Yield per kW — about 1,360 units per kW per year here at a good tilt, reduced for east, west or north-facing panels and for flat or steep tilts.
  3. System size = yearly use ÷ yield per kW, rounded up to whole panels.
  4. Roof check — each panel needs roughly 2.6 m² including spacing, and the planner leaves space for access. If your roof is too small it says how much of your use you can cover.
  5. Savings and payback = generation × your tariff, compared with the system cost.

Orientation and tilt

In Pakistan the sun tracks across the southern sky, so south-facing panels tilted around 30° produce the most over a year. East or west-facing arrays lose roughly a tenth. The Plot Orientation Guide explains how your plot’s facing affects this.

Design for wind

Rooftop frames must be designed for strong gusts. Poorly anchored locally made frames can fail in storms — ask for a structural check of the mounting.

How to use the rooftop solar planner

  1. 1Enter your monthly electricity use in units (kWh) from your bill.
  2. 2Enter the usable roof area.
  3. 3Choose which way the panels face and their tilt.
  4. 4Enter the panel size, your tariff and the system cost per kW.
  5. 5Read the system size, panel count, generation, savings and payback.

Frequently asked questions

+What size solar system do I need for my house?

Divide your yearly units by about 1,360 (the approximate yearly output of 1 kW in Islamabad–Rawalpindi). A home using 600 units a month needs roughly 5–6 kW.

+How much roof space does a 10 kW solar system need?

About 17 panels of 585 W, needing roughly 45 m² (around 480 sq ft) including spacing.

+Which direction should solar panels face in Pakistan?

South, tilted at about 30°, for the most yearly generation.

+How long does solar take to pay back?

It depends on the system price, your tariff and how much of the output you use. The calculator estimates it from your figures.