Solar for Plastic Injection Moulding and Packaging Units

This guide explains where the power goes in a moulding or packaging unit, how a solar plant is sized around it, and what to prepare before a site survey.

Where the power goes in a moulding unit

An injection moulding machine has two main energy users. Blow moulding, extrusion and film lines for packaging have the same pattern, with different proportions.

Much of this load is steady through a shift, which suits solar. Warm-up and motor starts create peaks, which matter for demand charges and backup.

Diagram

Plastic moulding and packaging

Heaters and motors

Steady daytime load

Shifts

Day shift suits solar

Peak hours

Grid or battery

Fixed-pump and servo machines

Many older machines in Punjab use a fixed-displacement hydraulic pump driven by a motor at constant speed, even when the machine is cooling or waiting. Newer machines often use a servo motor or a variable drive on the pump, so the motor only works hard when the machine needs pressure.

For solar, this means a lower base load between strokes, so the same plant covers a bigger share, and softer motor starts. Retrofitting drives is a decision for your machine supplier, not part of the solar plant; we design around the machines you have and note in the survey where drives could reduce load.

Three-phase design

Moulding and packaging units run on three-phase supply, from a 400 V connection for small units to an 11 kV connection with their own transformer for larger plants. The solar plant uses three-phase on-grid string inverters, sized and distributed to match the load. Our guide to three-phase vs single-phase inverters explains the basics.

Design points specific to this sector:

1. Phase balance. Machines are three-phase, but lighting, offices and some auxiliaries are single-phase. We check the balance so one phase is not overloaded.
2. Inverter placement. Inverters go in a ventilated, dust-controlled area, away from granulator dust and hot machine exhausts.
3. Cable routes. DC and AC cables are routed away from hot barrels, hydraulic oil lines and forklift paths.
4. Protection. Correctly rated DC and AC breakers, surge protection and earthing are part of every design. See our range of breakers and protection.

Power quality: VFDs, heaters and your controllers

Moulding machines use electronic controllers and temperature controllers that dislike voltage dips and spikes. Drives on motors can also add harmonic distortion to the factory supply.

On a grid-connected plant, the grid sets voltage and frequency and the inverters run in parallel with it, so a correctly designed plant does not normally upset machine controllers. What we check during design:

• Existing harmonics. With many drives on site, we look at supply quality before adding inverters.
• Voltage at the connection point. Long cables and weak transformers can push voltage up when solar is high and load is low, such as at lunch breaks. Settings and connection point are chosen to avoid nuisance trips.
• Power factor. Solar changes how much active power comes from the grid, so existing capacitor banks should be reviewed with the design.

Size the plant to your daytime load

New solar connections now come under NEPRA's net billing rules, notified on 9 February 2026. Imported units are billed at your normal tariff, while exported units are credited at a much lower rate. Solar capacity cannot exceed your sanctioned load. The full rules are in our net metering and net billing guide.

For a moulding or packaging unit this means one thing: size the solar plant so that most of its output is used by your machines during working hours. Our guide to sizing under net billing shows the method step by step.

Shift patterns change the answer:

• Single day shift: solar matches the load well; size close to the daytime base load.
• Two shifts: the evening shift still needs grid or generator power; size to the day shift.
• 24-hour running: solar covers part of the day; battery storage may help, depending on outages and tariff.
• Fridays and holidays: if the plant stops one day a week, that day's solar is mostly exported, which is worth less. Factor it in.

How to estimate the benefit yourself

We do not publish savings figures, because every factory's load and tariff is different. The numbers below are round illustrative values only, not a forecast.

For example, if a unit uses about 2,000 units on a working day, and a load study shows about half of that falls between 9 AM and 4 PM, roughly 1,000 units a day are available for solar to cover directly. Multiply the units solar actually covers by your full per-unit tariff to see the bill effect. Then allow for lower winter output, smog days and off days. A good proposal shows this calculation with your own bills and states its assumptions.

Demand charges and warm-up peaks

Larger industrial bills include a fixed charge based on maximum demand (MDI). In a moulding unit, the highest demand often comes at start-up, when many machines heat their barrels at once, or when motors start together. If that happens at 7 AM, solar output is still low and the peak lands on the grid.

Two simple steps help before any battery is considered:

1. Stagger warm-up. Start barrel heating machine by machine rather than all at once.
2. Time heavy starts. Where the process allows, start large motors and chillers after solar output has built up.

Our guide on MDI in your electricity bill explains how demand charges are calculated and where solar does and does not help.

Outages, generators and batteries

Standard on-grid inverters switch off when the grid fails. For a moulding unit, an outage mid-cycle can mean scrap parts, purged material and a long restart.

• Generator integration. Most units already run a diesel or gas generator. With a proper controller, solar can share the load with the generator while keeping it above its safe minimum load. See our solar and generator hybrid guide.
• Battery storage (BESS). A battery can carry controllers and critical loads through short trips, smooth the handover to a generator and shave demand peaks. It needs a clear job your data supports. Read Battery storage (BESS) for factories: when does it pay?

For commercial inverters and BESS we work with brands including Huawei and Sungrow, alongside other approved brands. The exact model is chosen per project and listed in the BOQ.

Roofs and structures

Plastic and packaging units are often in sheds with metal sheet roofs. Panels can be fixed on sheet roofs with the right clamps and a structural check; see solar on tin and metal sheet roofs. Where roofs carry cooling towers or exhaust fans, an elevated structure keeps panels clear. Our in-house engineers design structures, our own team fabricates and assembles them on site, and they carry a 3-year Solar Works Pakistan structure warranty.

Solar plant price for a moulding or packaging unit

Factory systems are quoted per project after a site survey and design.

What to prepare before a site survey

• 12 months of electricity bills, including MDI.
• Machine list: tonnage, fixed pump or servo, heater load where known.
• Chillers, compressors and dryers with ratings.
• Shift pattern and weekly off days.
• Generator rating, fuel and monthly running hours.

How Solar Works Pakistan delivers factory projects

Solar Works Pakistan is a Faisalabad-headquartered solar EPC, engineering and trading company, founded in 2021, with a branch in Lahore. We have served 300+ customers, including 50+ industrial clients, and build projects from about 6 kW to megawatt scale. Load analysis, AutoCAD design and structural design are done in-house, and our own teams install, test and commission. Major equipment carries the manufacturer's warranty per product. After a complaint is registered, we target sending service personnel within 48 hours to begin diagnosis. See our industrial and commercial solar page.

Get today's price or a free site survey

Send us 12 months of bills and your machine list. Our engineers will tell you plainly how much of your load solar can carry.

• 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 factories throughout Punjab, and site surveys are normally free. You can also contact us online.

Frequently asked questions

Can an injection moulding machine run on solar?

Yes, on a grid-connected or hybrid plant. Solar supplies the heaters and motors during the day, and the grid or a generator covers the balance. Running a moulding machine on solar alone is not practical, because output changes with cloud and stops at night.

How much solar does a plastic factory need?

It depends on the share of your load that falls in working daylight hours, your sanctioned load and your roof. A load study during the site survey sets the size. Under net billing, sizing to daytime self-use usually makes most sense.

Do servo machines make solar more worthwhile?

They lower the base load between injection strokes and soften motor starts. That means a given solar plant covers a larger share of the factory's needs. Whether to convert machines is a separate decision for your machine supplier.

Will solar inverters disturb my machine controllers?

Not normally. On a grid-connected plant the inverters run in parallel with the grid. We check supply quality, voltage at the connection point and power factor correction during design to avoid nuisance trips.

Will solar reduce my MDI charges?

Not by itself. Peaks often happen at morning warm-up when solar is low. Staggered warm-up, timed motor starts or a battery designed for peak shaving can help.

Does solar work during load-shedding in a moulding unit?

Standard on-grid inverters switch off when the grid fails. With a generator controller, solar can share load with your generator. A battery can carry critical loads through short outages.

Sources

1. Net billing facts are carried over from our net metering and net billing guide, which lists its own 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. The peak-hour tariff note is carried over from our BESS for factories guide, which lists its own sources.