Planning Solar for a New Factory Building

This guide is for owners, architects and project managers planning a new industrial building in Punjab. If you already run a factory and want to add solar in stages, read our phased solar rollout guide. If you are building a house, see making a new house solar-ready.

Why the design stage matters

A factory shed lasts decades, and solar panels last decades too. When solar is added to a shed that was never designed for it, these problems come up again and again:

• purlins that are too light or spaced wrongly for panel rails, needing extra steel or an independent frame;
• skylights, ridge ventilators and exhaust fans scattered across the best part of the roof;
• a roof sheet that will need replacing long before the panels are worn out;
• no space in the LT panel for a solar incomer, and no room for inverters near it;
• a sanctioned load set for today's machines, which then caps the solar plant under net billing.

None of these is hard to avoid if the solar engineer sits with the architect and the shed supplier early.

Diagram

Solar for a new factory building

Roof

Design for panel load from the start

Electrical

Space for inverters and cable routes

Phases

Plan for later expansion

The roof: designed for panels from day one

Tell the structural designer about the solar load

Panels and racking add dead load, wind uplift and, on some designs, point loads at the fixings. As a rough guide, panels with a light fixed frame add about 15 to 25 kg per square metre, but your structural engineer sets the design value from the actual panels and frame. Our guide to roof load and solar panels explains how weight and wind act on a roof.

For a pre-engineered (PEB) steel shed, ask the supplier to include the solar load as a collateral load in the design, and to check uplift at the edges and corners where wind is strongest.

Purlins, sheet profile and fixings

On a sheet roof, panel rails are fixed through the sheet into the purlins. That works best when:

• purlin spacing suits the panel rails, which the solar designer can give the shed designer before purlins are ordered;
• the sheet profile and thickness are chosen with solar fixings in mind;
• the sheet itself is durable, because replacing a sheet under a working solar plant means taking the panels off first.

Our guide to solar on tin and metal sheet roofs covers fixing methods and leak prevention. For an RCC roof, anchor points or plates can be cast in during construction, so no drilling through the waterproofing is needed later.

Orientation, pitch and clear zones

In Punjab, a south-facing roof gives the most energy, while east and west slopes spread output across the morning and afternoon. Most factories cannot turn the building for the sun, and should not, because process flow and plot shape come first. What you can usually control:

• Which roof slopes carry the panels, so the main panel area faces south, east or west rather than steeply north.
• Where skylights, ventilators and exhaust fans go. Group them in one strip, or on north-facing slopes, so the rest of the roof stays clear.
• Shade sources. Parapets, water tanks, chimneys and a taller building next door all cast shade. See how shading cuts solar output and the best panel angle and direction for Punjab.

Access, cleaning and safety

Panels on a factory roof need cleaning and inspection for decades. Plan for:

• walkways between panel rows and safe access from inside the building;
• anchor points or lifelines for people working at height;
• a water point on the roof for cleaning (see solar panel cleaning);
• clear paths and isolation points for firefighters, and no DC cables run across walkways.

Exhaust fans and process vents that throw out oil mist, lint or dust should not sit upwind of the panels. Our structure design process explains how we design frames for Punjab wind and heat.

If the roof will not be large enough, keep options open on the ground: a ground-mounted array on spare land or solar carports over the parking area.

The electrical connection: size it for the final load

Sanctioned load caps the solar plant

Under NEPRA's net billing rules, notified on 9 February 2026, your solar system cannot be larger than your sanctioned load, with an overall cap of 1 MW per facility. Systems above 25 kW need NEPRA concurrence and a one-time fee per kW, and 250 kW and above needs a load flow study. See our net metering and net billing guide and the 25 kW rule.

For a new factory, this means the sanctioned load you apply for should reflect the full machine load you expect, not only the first production line. Raising it later is possible but adds paperwork and time; see how to increase sanctioned load.

The transformer

Most new industrial connections above a modest load need their own transformer, paid for by the consumer, and many factories take supply at 11 kV. When sizing it, consider:

• the full future machine load, not just phase one;
• the solar plant's output flowing back through it at midday when the factory is lightly loaded, for example on holidays;
• the 80% rule: a DISCO can refuse new solar applications on a transformer whose connected generation has reached 80% of its rating, so a shared or undersized transformer can block your plant.

A dedicated transformer sized with solar in mind avoids most of these problems.

LT panel, inverter room and cable routes

Ask for these in the electrical design:

Size the solar for the load you will actually run

A new factory has no electricity bills to size from. Instead, estimate the load from the machine list:

1. List every machine with its rated kW, expected running hours and which shifts use it.
2. Separate daytime load from evening and night load.
3. Estimate the steady daytime base load: the power the factory draws on a normal working day between morning and afternoon.
4. Size the first solar plant close to that daytime base load, so most of its output is used on site.

Under net billing, exported units earn far less than grid units cost. For example, if a new unit expects a steady 300 kW of daytime machine load on working days, a solar plant sized near that figure would use most of its output on site, while a much larger plant would export more on holidays and light days. These are round illustrative numbers, not a design.

Once the factory is running, our energy audit guide explains what to log to confirm the size. If maximum demand charges matter to your tariff, read what MDI means on your bill; if evening shifts or outages are a concern, see battery storage for factories.

Build ready to grow

Many factories install solar in stages. Design the roof, transformer, LT panel and inverter room for the final plant, then install the first phase. Our phased rollout guide explains how to plan phase two without rework.

Planning timeline

What solar-ready costs

How Solar Works Pakistan helps with new factories

Solar Works Pakistan is a solar EPC, engineering and trading company founded in 2021, with its head office in Faisalabad and a branch in Lahore. We have served 300+ customers, including 50+ industrial clients, on projects from about 6 kW to megawatt scale.

• In-house engineering and AutoCAD design. We can work with your architect, PEB supplier and electrical consultant, giving them the panel layout, loads and fixing details they need. See why in-house design matters.
• Structures designed in-house and assembled by our own teams on site, with a 3-year Solar Works Pakistan structure warranty.
• Detailed BOQ naming brand, model, quantity and warranty for every item. Panels, inverters and batteries carry the manufacturer's warranty per product.
• Installation, testing and safe commissioning by our own teams, on a project-specific schedule.
• After-sales: a 1-year service warranty under applicable project terms, and a 48-hour target to send service personnel after a complaint is registered.

See our industrial and commercial solar page.

Get today's price or a free site survey

Send us your site plan, building drawings, machine list and expected shifts. We will mark up what the roof and electrical design need for solar.

• WhatsApp or call: 0336 666 4321
• Email: info@solarworks.pk
• Head office: Main Boulevard, Sargodha Rd, Block F FDA City, Faisalabad (Faisalabad page)
• Lahore branch: 2nd Floor, Jeff Heights, Gulberg, Lahore (Lahore page)
• Hours: 9:00 AM to 6:00 PM, daily

We serve all of Punjab, and site surveys are normally free. You can also contact us online.

Frequently asked questions

When should I involve a solar engineer in a new factory project?

At the layout and structural design stage, before the PEB shed or roof slab is designed and before the DISCO application is filed. That is when roof load, purlins, skylights, sanctioned load and the transformer can be set for solar at little cost.

Does a new factory roof need to be designed for solar panels?

Yes, if you plan to install them. Panels and racking add dead load and wind uplift, and the fixings must land on purlins or anchors. Your structural engineer should include the solar load in the design.

How big a sanctioned load should I apply for?

Enough for the full machine load you expect, including later lines. Under net billing your solar plant cannot exceed your sanctioned load, so setting it too low also caps your solar.

Can I size solar for a factory that is not running yet?

Yes, from the machine list, running hours and shifts. Size the first plant to the steady daytime load, then confirm with real data once production starts.

Should the inverters go on the roof or in a room?

Usually in a ventilated room near the LT panel, away from process heat, dust and water. That keeps them cooler, cleaner and easier to service.

Is a south-facing roof essential?

No. South gives the most energy, but east and west slopes still work well. Keep the main panel areas free of skylights, ventilators and shade.

Sources

1. Net billing limits (sanctioned-load cap, 1 MW cap, 25 kW rule, 250 kW load flow study, 80% transformer rule) are carried over from our net metering and net billing guide, which lists its sources, including the NEPRA (Prosumer) Regulations, 2026, SRO 251(I)/2026: https://ke.com.pk/wp-content/uploads/2026/04/8.-NEPRA-Prosumer-Regulations-SRO-251I2026-09-02-26.pdf
2. Indicative roof dead loads are carried over from our roof load guide, which lists its sources.