Cutting Scope 2 Emissions with On-Site Solar

For a growing number of UK manufacturers, the decision to install solar is no longer driven purely by the electricity bill. It is driven by the customer. OEM and retail buyers such as JLR, Nestle, Tesco, GSK and Unilever increasingly require Scope 2 and Scope 3 emissions reporting from their suppliers, and sites without renewable generation now risk losing contracts. On-site solar is one of the cleanest, most defensible ways to demonstrate a real Scope 2 reduction, and the reporting it produces slots directly into the frameworks your customers audit against.

This is also one of the clearest gaps in the market. Most competitor content treats solar as an energy-cost story and stops there. The Scope 2 and supply-chain reporting angle stays under-served, despite being the number-one reason many manufacturers now act. This guide closes that gap.

What Scope 2 actually measures

Scope 2 covers the indirect emissions from the electricity your site buys and consumes. Under the GHG Protocol, every manufacturer reports Scope 2 two ways, and both matter to a customer auditor.

The location-based figure multiplies your grid consumption by the average carbon intensity of the national grid. It reflects the physical reality of the electrons you draw. The market-based figure reflects the specific energy you have contracted, including any renewable instruments, green tariffs or on-site generation you can claim.

On-site solar is one of the few interventions that moves both numbers at once. When you self-consume a kilowatt-hour of solar, you have not drawn that kilowatt-hour from the grid at all. Your metered import falls, so your location-based Scope 2 falls. And because the generation is physically yours and directly consumed, it is one of the strongest possible market-based claims, cleaner than a purchased certificate, because the reduction is happening behind your own meter.

Why self-consumption is the metric that counts

For manufacturing, self-consumption is where the emissions story and the financial story converge. A correctly sized rooftop or ground-mounted array can self-supply 30 to 60 percent of a plant’s annual demand. Because manufacturing loads are daytime-weighted, driven by compressors, motors, process heat, refrigeration and machinery, that self-consumption sits high. Every self-consumed unit is a unit of grid import removed from your Scope 2 inventory.

The working sizing rule reinforces this. We install 70 to 90 percent of peak daytime demand to maximise self-consumption and avoid spilling cheap exports onto the Smart Export Guarantee. High self-consumption is good for payback and good for your carbon accounting at the same time. You can read the full financial model on our cost page.

How on-site solar feeds EcoVadis, CDP and SBTi

The reason on-site solar is so valuable in a supplier audit is that it produces hard, metered, third-party-verifiable data rather than an estimate. Here is where the generation figures land in each framework.

Framework	What it assesses	How on-site solar feeds it
CDP (incl. Supply Chain)	Disclosure of Scope 1, 2 and 3 emissions and energy data, scored and shared with requesting customers	Metered annual generation and self-consumption reduce reported Scope 2 and evidence a live renewable-energy programme
SBTi	Science-based near and long-term reduction targets against a baseline	On-site generation is a direct, owned reduction lever counted toward validated Scope 2 targets
EcoVadis	Environment, labour, ethics and procurement scorecard used as a contract condition	On-site renewables and a documented energy strategy lift the environment pillar score

Across the frameworks the mechanism is the same. Your solar monitoring platform records generation and self-consumption to the kilowatt-hour, that figure reduces your market-based and location-based Scope 2, and the reduction is auditable back to the meter. For manufacturers under supply-chain pressure, an on-site array is one of the most visible and verifiable decarbonisation measures you can put in front of a customer.

The automotive supply chain is furthest ahead

The clearest example is automotive. OEM sustainability mandates cascade to Tier-1 and Tier-2 suppliers, and OEM scoring under CDP, EcoVadis and SBTi is increasingly tied to renewable-energy share. Tier-1 supplier audits now routinely review on-site generation. If you supply into JLR Reimagine, Stellantis, Ford or BMW programmes, on-site solar is fast becoming table stakes rather than a differentiator. Our automotive manufacturing page covers the sector-specific design constraints in detail.

Food and beverage is close behind. BRCGS Food Safety Issue 9 references energy and environmental management, and retailer audits increasingly require renewable-energy disclosure. Pharma and life sciences face intense customer and investor ESG scrutiny under SBTi and CDP, which pairs neatly with the very high, flat 24/7 baseload from cleanroom HVAC, chilled water and compressed air.

What a Scope 2 reduction looks like in practice

The dossier figures give a grounded sense of scale. These are representative ranges for UK manufacturing installs, not promises tied to any named site.

Representative install	System size	Annual generation	Annual CO2 saved	Typical payback
Manufacturing plant	250 to 800 kW	230,000 to 740,000 kWh	53 to 170 tonnes	6 years
Food and beverage plant	400 to 1,200 kW	370,000 to 1,100,000 kWh	85 to 253 tonnes	5.5 years
Automotive plant	500 to 2,000 kW	460,000 to 1,840,000 kWh	106 to 423 tonnes	5 years
Pharmaceutical site	300 to 1,000 kW	275,000 to 920,000 kWh	63 to 212 tonnes	6 years

The carbon saving in that final column is, in effect, your annual Scope 2 reduction from the array. An automotive plant offsetting up to 423 tonnes of CO2 a year is reporting a material step change against its SBTi baseline, not a rounding error. And because the panels are warranted for 25 years, that reduction repeats annually for the life of the system, with only routine cleaning and one inverter replacement over the system’s real-world 30 to 35 year life.

The embodied-carbon question does not undermine the case. Modern crystalline-silicon panels have a carbon payback of 18 to 30 months in UK conditions, so over a 25-year life a UK manufacturing PV system displaces many times its own embodied carbon. That is a credible answer to any auditor who probes the lifecycle maths.

Where the electricity mix still needs a PPA

Honesty matters in front of an auditor, so it is worth being clear about the limits. On its own, rooftop solar rarely covers all demand at an energy-intensive site. Most installs offset 30 to 60 percent of annual consumption, and the remainder is typically covered by a green power purchase agreement, on-site battery storage, or continued grid import. Combining rooftop PV with a corporate PPA on a remote solar farm is the most common route to a fully renewable supply, and therefore to a near-zero market-based Scope 2 claim, for heavy industry.

Battery storage extends the reach of self-consumption where you run significant night shifts or face heavy DUoS red-band charges, and starts to pay above roughly 250 kW of PV in those conditions. We model the battery case alongside the PV so the Scope 2 and financial cases are visible together.

The compliance groundwork that makes the claim stand up

A Scope 2 claim is only as good as the certification behind the system that generates it. For the reduction to hold up in an audit, the install needs to be done to standard.

MCS commercial certification is required for Smart Export Guarantee eligibility and signals a properly certified install. You can verify an installer’s status directly through MCS Certified. A G99 application is required for connections above 17 kW per phase, and DNO study responses typically run to around 65 working days with actual connection dates of 6 to 18 months on constrained networks, so the connection is usually the longest item in the programme. We submit the DNO application alongside the structural survey so the clock starts on day one.

Fire-safety design to SPF1981 v3 is now effectively an insurer requirement for rooftop PV, and enterprise procurement teams routinely expect BS EN ISO 9001, 14001 and 45001 certification from their suppliers. All of this is part of the documentation trail that a customer auditor will want to see alongside your generation data.

Funding the reduction without touching the capital budget

The strongest supply-chain case in the world still has to clear the finance director. The good news is that the Scope 2 reduction does not have to compete with production-line investment. Solar PV qualifies as plant and machinery, so the Annual Investment Allowance covers the first million pounds of qualifying expenditure at 100 percent, delivering up to roughly 25 percent effective tax relief in year one. Energy-intensive sectors can also benefit from Climate Change Agreements, where reduced metered grid consumption directly improves performance against target. Our grants and funding page maps the full picture, including the Industrial Energy Transformation Fund.

Where capital is genuinely unavailable, a PPA delivers day-one savings against your current grid tariff with zero capex, and the array still produces the metered generation data your customers want to see. The Scope 2 benefit and the reporting arrive regardless of how the system is funded.

Turning solar into audit-ready evidence

Cutting Scope 2 with on-site solar is not only achievable, it is one of the few measures that improves your energy cost, your carbon inventory and your customer scorecard in a single move. The metered generation reduces both your location-based and market-based Scope 2, the data feeds CDP, SBTi and EcoVadis without manual estimation, and the certified install gives the whole claim an audit trail.

If a customer supply-chain audit is on your horizon, the practical next step is a feasibility study modelled from your own half-hourly meter data, so the projected Scope 2 reduction is grounded in how your plant actually runs. Request a sized and priced proposal through our quote page, and we will show you the carbon and the cash side by side.