Solar system for a factory in Lahore

The industrial roof is the best solar asset in Punjab

Nothing else comes close. A factory in Sundar Industrial Estate, Kot Lakhpat, Quaid-e-Azam Industrial Estate or on Ferozepur Road has three things a house will never have: acres of flat unshaded sheet roof, a load that runs all day, and a tariff that punishes every unit purchased.

Put those together and industrial solar in Lahore returns capital faster than almost any other equipment purchase a factory makes. Not because the panels are special. Because the alternative, buying units from the grid at industrial rates, is so expensive.

The catch, and it is a real one, is that industrial jobs go wrong in ways residential jobs never do. Roof failure. Phase imbalance. Reverse power tripping the LT breaker. A 200kW array is not a 5kW array multiplied by forty, and treating it that way is how installers destroy a shed roof.

Load bearing comes before kilowatts

The first question on an industrial survey is never "how many units do you use". It is "what is holding the roof up".

Panels plus structure add roughly 12 to 15 kg per square metre on a sheet roof and 18 to 22 kg per square metre on an elevated ballasted frame over a flat RCC slab. Add wind uplift, which in Lahore's pre-monsoon squalls can briefly reach 120 km/h, and the load case is not trivial.

What is found on Lahore factory roofs, in rough order of frequency:

• Pre-engineered steel shed, Z-purlins at 1.5m centres. Fine. Rail clamps bolt straight to the purlin through the sheet with EPDM sealed fasteners.
• Old girder-and-sheet shed, 1980s vintage. Common in Kot Lakhpat and Badami Bagh. Needs a purlin survey and often intermediate reinforcement, adding PKR 3,000 to 5,000 per kW.
• Asbestos cement sheeting. Cannot take direct fastening and is a health hazard to drill. Either replace the sheeting or build an independent frame that lands on the columns, not the roof.
• Flat RCC slab over a two-storey stitching or packing hall. Usually strong, but check the waterproofing membrane age first. Penetrating a fifteen year old membrane in June guarantees a leak by August.
• Ground-mount on spare yard land. Often the cheapest option where the factory has an unused strip. Costs more in civil work but avoids the roof question entirely.

A structural sign-off before design is non-negotiable. The mounting rates used in quotes, PKR 7,000 per kW for standard and PKR 12,000 per kW for elevated frames, assume a sound roof. Reinforcement is extra and it is better to know at survey than at commissioning.

Sizing against the industrial tariff

Industrial connections in Lahore are billed on energy plus a maximum demand charge on peak kVA. Solar cuts the energy component hard and the demand component only partly, because peak demand often occurs during a motor start rather than at solar noon.

Practical sizing rule for a single-shift factory: size the array at 60 to 80 percent of average daytime demand. That keeps almost all generation self-consumed, avoids reverse power flow issues, and does not depend on export credit to make the numbers work.

System	Panels (645W bifacial)	Roof area needed	Units per month	Turnkey cost
50 kW	78	3,200 sq ft	6,200 - 7,400	PKR 5,600,000 - 6,600,000
100 kW	156	6,400 sq ft	12,500 - 14,800	PKR 10,500,000 - 12,500,000
150 kW	233	9,600 sq ft	18,700 - 22,200	PKR 15,000,000 - 18,000,000
200 kW	311	12,800 sq ft	25,000 - 29,600	PKR 19,500,000 - 23,500,000

Panel cost inside those numbers is PKR 21,000 per 645W bifacial module and PKR 19,500 per 585W Tier-1 where a cheaper build is specified. Astronergy 585W N-type at PKR 25,450 goes into premium builds where roof area is the limiting factor and higher efficiency per square foot earns its price.

What sits inside a 100kW build

Transparency on the bill of quantities matters more at this size, because the difference between a good and a bad 100kW system is buried in components nobody photographs.

• Array. 156 bifacial modules in strings sized to the inverter MPPT voltage window, with string currents kept under the fuse rating.
• Inverters. Either two 50kW three-phase string inverters or four 25kW units. Multiple smaller inverters cost slightly more but mean a single failure takes out a quarter of the plant instead of half.
• DC side. Combiner boxes with string fuses and Type-II surge protection, 6mm solar cable in UV-rated conduit, branded MC4 connectors crimped with the correct tool.
• AC side. AC combiner, four-pole MCCB, Type-II AC SPD, and integration into the LT panel with a properly rated breaker and correct cable derating for a 45 degree ambient.
• Earthing. Separate array earth pit and inverter earth, bonded through a common bar. Skipping this is the single most common shortcut on cheap industrial quotes.
• Monitoring. Plant-level monitoring with string-level current visibility, so a dead string is noticed in a week rather than at the annual audit.
• Structure. Hot-dip galvanised, not painted MS. Painted structure in Lahore's humidity and industrial air starts rusting inside three years.

Three-phase realities and reverse power

Every factory here is three-phase, and every factory here has an unbalanced load. Motors get added over the years wherever there was a spare way in the panel. Before a solar plant is energised, phase currents need measuring across a full production day and the load redistributing.

The second issue is reverse power flow. If the factory runs a single shift and the array is oversized, midday generation on a Sunday or a shutdown day pushes power back through the transformer. LESCO's protection at the feeder will notice. On a net-metered connection that is fine and expected within limits. On a system without an approved net meter, an export relay or a zero-export controller is mandatory, not optional, and it should be tested on site by dropping the load and watching the meter.

Anyone considering full grid independence should read the off-grid guide first. For a factory it is almost never economic, since the storage needed to carry motor loads through a night dwarfs the array cost. The off-grid service page explains where it does make sense, mostly for remote or unconnected sites.

ROI, and the things that quietly erode it

A 100kW plant at PKR 11,500,000 generating 13,500 units a month, displacing purchased units at an effective PKR 52 per unit, saves roughly PKR 702,000 a month. That is a payback near 17 months on paper.

Nobody achieves the paper number. Here is what pulls it back to a realistic 26 to 34 months:

• Factory shutdowns. Eid weeks, maintenance shutdowns and Sunday closures mean 10 to 18 percent of annual generation is either exported at low buyback or curtailed.
• Smog season. December and January generation in Lahore drops 25 to 35 percent against the annual average. Real numbers in winter solar output.
• Soiling between cleans. Industrial roofs near Kot Lakhpat and Multan Road collect cement dust and oil-bearing particulates. Unwashed panels lose 8 to 20 percent.
• Net meter delay. Six to twelve weeks between commissioning and meter installation is normal for large connections.
• Degradation and inverter replacement. Budget one inverter replacement around year nine.

That is still an excellent return. It is simply not the one printed on a marketing sheet, and any factory owner comparing quotes should ask which of those five items each vendor has accounted for. For a broader view on whether the economics still hold this year, see is solar still worth it in 2026.

Net metering and paperwork at industrial scale

The application goes to LESCO with the sanctioned load documents, factory registration, single-line diagram, inverter and panel datasheets, and the installer's test report. Sanctioned load must cover the inverter capacity. If it does not, a load extension application comes first and that alone can take four to eight weeks at the subdivision.

Expect a physical inspection. Expect at least one round of corrections on the single-line diagram. Handling this end to end is part of the net metering service, and what changed under the current rules is in net metering 2026 changes. Where export approval is not viable, running without net metering is a legitimate path for a factory that consumes everything anyway.

Keeping a large array producing

Industrial arrays fail silently. A string goes down, output drops four percent, and nobody notices for eight months because the bill is still lower than it used to be. String-level monitoring plus a quarterly walk-through fixes that.

Cleaning schedule for Lahore: monthly from November to February, six-weekly the rest of the year, and once immediately after the first heavy monsoon rain, because rain here deposits more mud than it washes off. Rates on cleaning cost and the service on panel cleaning. Fault work is covered under repair, with typical charges listed in solar repair cost in Lahore.

Factories are served across Sundar, Kot Lakhpat, Raiwind Road, Multan Road and Ferozepur Road, along with the commercial belts of Johar Town, Wapda Town, DHA and Gulberg. Smaller units on a workshop scale may want the 15kW pricing instead, and full build scope is on installation. Rough estimates start on the calculator, and detailed enquiries through contact.