Sizing
Size your system
An engineer verifies the load and the site before any proposal.
Solar system sizes
System size is driven by how much electricity a site consumes and when. As a planning figure, each kW covers roughly 120 units of monthly consumption. The sizes below are the standard offerings; a site survey turns an indicative size into a real one.
| System | Typical monthly units | Approx. roof area | Detail |
|---|---|---|---|
| 3 kW | 360 | 300 sq ft | See the 3 kW page |
| 5 kW | 600 | 500 sq ft | See the 5 kW page |
| 10 kW | 1200 | 1000 sq ft | See the 10 kW page |
| 15 kW | 1800 | 1500 sq ft | See the 15 kW page |
| 25 kW | 3000 | 2500 sq ft | See the 25 kW page |
Typical figures are planning values derived from roughly four peak-sun-hours a day in Punjab, derated. They are not a guarantee of output.
Six inputs, in roughly the order they matter. A size chosen without them is a budget decision wearing an engineering label.
How much you consume
Twelve months of units where possible, not one bill. Roughly 120 units a month per kW is the planning figure everything else adjusts.
When you consume it
A load that runs in daylight is offset directly. One that runs after sunset needs net metering to bank the surplus, or storage to carry it.
Usable roof area
About 100 square feet of unshaded area per kW. Parapets, tanks, stairwells and neighbouring buildings all reduce what is genuinely usable.
Connection phase
Single or three phase changes the inverter, the array arrangement, and how load is balanced across the installation.
What must survive an outage
Backup is a separate question from size, and the answer drives the battery rather than the array. It is also where most of the cost variation lives.
The existing installation
The board, protection and earthing decide what can be connected safely — and occasionally decide that remedial work comes first.
Bigger is not automatically better
An oversized array generates energy the site cannot use. Without net metering that surplus is simply lost, and with it the value depends on how the export is credited — which is decided by regulation rather than by the installer. Either way, capacity you never consume is capacity you paid for twice: once in equipment, once in the roof area it occupied.
Undersizing has the opposite failure. It trims a bill rather than changing it, and the second phase people plan to add later is more expensive than the capacity would have been at the outset, because the inverter, the cabling and the structure were all sized for the smaller system.
The honest middle is a size derived from twelve months of consumption, with the design leaving room for a defined expansion if one is genuinely likely. That is a decision to make before equipment is ordered, and it is one of the things a site survey settles.