Solar panels for manufacturers: Plastics & Injection Moulding

Load profile: moulding machines and chillers on 24/5 give exceptional self-consumption.

Injection and blow moulding is one of the best-matched processes in UK manufacturing for rooftop solar, which is why solar panels for plastics manufacturers so often produce a payback around 5.5 years. Moulding machines, their chillers and the compressed-air system pull a very high, daytime-heavy load that runs almost flat through the working shift. On a 24/5 or 24/7 pattern that gives exceptional self-consumption, because the midday generation peak is consumed on site the instant it is produced rather than exported cheaply.

Why moulding sites self-consume so well

The economics of solar for a manufacturer come down to one number: how much of what you generate you use yourself. A plastics site scores highly on that measure. The moulding machines run continuously, the cooling-water and chiller loads track daylight and warm weather, and compressed air adds a firm base. Put together, a well-sized array on a 24/5 moulding site commonly self-consumes 80 to 90 percent of its output. Every one of those units displaces grid electricity at your full import rate of roughly 22 to 32p, while the small surplus you export earns the Smart Export Guarantee rate. That split is what drives one of the faster paybacks in manufacturing.

We size from at least twelve months of half-hourly meter data rather than roof area, because moulding sites carry high rooftop plant density and mixed machine loads that a rule of thumb gets wrong. A typical plastics and injection moulding array is 300 kW to 1,000 kW, around 550 to 1,850 panels across 1,800 to 6,000 square metres of roof, generating 275,000 to 920,000 kWh a year. We install to 70 to 90 percent of peak daytime demand to keep generation on site.

Machine loads shape the design

Large three-phase machine loads and variable-speed drives can raise power-quality and harmonics considerations, so we specify inverters to suit the loads actually on your site rather than fitting a generic package. Chiller and cooling-water plant is coordinated during the connection works so production is not disturbed, and because rooftop plant density on a moulding site is often high, a shading and structural study is completed before we fix the final system size. Pre-2000 roofs need engineer sign-off before ballast or rail loading, and any asbestos-cement roof has to be replaced before PV can go on it; the structural survey at the start of the project settles all of this.

The capital case, three ways

Plastics manufacturers typically supply automotive, packaging and consumer-goods customers who increasingly ask for Scope 2 disclosure, so there are two reasons to act: the bill and the customer. Either way, the finance director wants a defensible number. We build the full discounted-cash-flow model from your own data: simple payback, IRR (typically 12 to 22 percent), NPV at your discount rate, and an LCOE that for a moulding site usually lands at 4 to 7p/kWh against 22 to 32p grid retail.

We then model the three funding routes against your current tariff so the board can choose on merit:

• Outright purchase for the best lifetime return, with the Annual Investment Allowance expensing 100 percent of the first £1m in year one. Solar is special-rate plant and machinery, so the route is the AIA, not full expensing.
• Asset finance or a lease to spread the cost over 7 to 15 years and keep it off the production budget, usually EBITDA-positive from year one.
• A power purchase agreement for zero capital and a day-one saving, with the array owned by a third party.

The cost guide shows the figures and the grants and funding page covers capital allowances and, for eligible sites, Climate Change Agreements.

Batteries and night shifts

If you run a genuine night shift, or you face heavy DUoS red-band charges, a battery can be worth modelling alongside the PV. It lets you store daytime generation and discharge it into the dark hours or out of the expensive red band, and on some sites it also opens flexibility revenue. For most 24/5 moulding sites the daytime self-consumption is already so strong that a battery is a secondary optimisation rather than a necessity, but we model the business case either way so you can see the numbers instead of guessing.

A representative plastics project

An injection-moulding manufacturer in the North West supplied packaging and consumer-goods customers, running energy-hungry moulding machines and chillers on a 24/5 pattern across a 4,600 square metre trapezoidal-metal roof. The board asked us to compare the capital three ways before committing. We modelled a 610 kW array, about 1,130 panels, at 84 percent self-consumption. First-year generation came in at 558,000 kWh, saving around £124,000 a year with simple payback at 5.6 years. Presented with outright, asset finance and PPA side by side, the board chose asset finance for balance-sheet ownership with day-one positive cash flow.

What to do next

Send twelve months of half-hourly meter data and your roof drawings, and we will return a sized, priced feasibility study with generation forecast and modelled IRR within seven working days. A single-day engineering survey follows, then a fixed-price proposal and a financial model your team can own. Try the savings calculator or ask for a free feasibility study now.