Guides
What your roof needs before it can carry solar
Four things decide it: whether the slab or structure can carry the load, whether there is enough unshaded area, whether the waterproofing can be penetrated or ballasted safely, and which way the usable area faces. Most Pakistani flat roofs pass, but the survey is what confirms it.
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Structure before area
A concrete slab in reasonable condition carries a rooftop array comfortably — the distributed load is modest. What needs checking is a slab already showing cracking or water damage, an older tin or asbestos roof, or a structure carrying a water tank the array will sit around. Strengthening, where it is genuinely needed, is a civil cost and should be quoted separately from the solar.
Usable area is smaller than total area
Parapets cast shadows, water tanks and stairwell housings occupy space, and rows need spacing so they do not shade each other in winter when the sun is low. A roof that looks generous on a plan is often materially smaller once those are subtracted, which is why area is measured on site and not from a satellite view.
Fixing without ruining waterproofing
Penetrating a slab means sealing every fixing properly, and a leak that appears in the first monsoon is expensive to trace. Ballasted structures avoid penetration entirely by using weight, which suits a sound flat roof and adds load. Which approach is right depends on the roof, and it should be stated on the quotation rather than decided on installation day.
Orientation and tilt, in that order
South-facing is best at this latitude, and east or west arrays lose some annual yield while producing earlier or later in the day — occasionally useful if your consumption is skewed. Tilt matters less than people expect within a sensible range; a slight tilt also helps rain wash dust off rather than letting it pool.
Is my roof suitable for solar panels?
Can panels go on a tin roof?
Yes, with the right mounting — rails fixed to the purlins rather than the sheet itself, and every fixing properly sealed. Fixing directly through the sheeting into nothing structural is a common shortcut and it is how arrays come loose in a pre-monsoon wind. Ask specifically what the structure is anchored to.
Will panels damage my roof?
Properly installed, no — and they shade the slab beneath, which slightly reduces heat gain into the rooms below. Badly installed, the risk is water ingress at unsealed penetrations. That risk is entirely a workmanship question, which is why the mounting method belongs on the written quote rather than being left to the fitting crew.
How much roof do I need per kW?
Roughly 80 to 100 square feet of genuinely usable, unshaded area per kW with current panel efficiencies, including row spacing. Higher-efficiency panels reduce that, which matters on a constrained roof and matters very little on an open one. Measure usable area, not total area, before applying the figure.
Rather have it done?
Solar installation covers the survey, the panels, the mounting structure, DC and AC wiring, protection and commissioning. A 3kW on-grid system in Islamabad starts near PKR 350,000 complete, and the figure that matters is the one that includes structure and wiring rather than panels alone.
Solar panel supply and installation in Islamabad — prices and scope