How do solar panels affect a commercial property's EPC rating?
- Tony Porter
- Jul 16
- 12 min read
Key takeaways
Commercial EPCs are calculated using SBEM (Simplified Building Energy Model), which is based on carbon emissions, not running costs. Solar PV directly reduces the Building Emission Rate (BER), improving the rating.
A well-specified commercial solar installation typically improves a building’s EPC rating by 1 to 3 bands. An EPC D building can reach EPC B in a single intervention.
The June 2026 government interim response confirmed that from 2031, all privately rented commercial buildings over 1,000 sq m must achieve EPC B, where cost-effective. Smaller buildings remain at the EPC E minimum.
CBRE estimates 58% of London office stock currently sits below EPC B. The supply of qualified contractors and assessors will tighten as 2031 approaches.
Solar is one of the highest-impact single interventions available for commercial EPC improvement, often outperforming insulation or mechanical upgrades per pound invested.
The EPC rating on a commercial property is no longer just a certificate on a filing shelf. It determines whether a building can be legally let, how much institutional investors are willing to pay for it, and whether a tenant's sustainability team will sign off on a lease. For landlords and owner-occupiers sitting on properties rated D, E, or below, that matters.
Solar panels are one of the most effective ways to improve a commercial EPC rating. They can move a building by one, two, or three bands in a single intervention. But the mechanics of how that works are not widely understood, and the regulatory picture has changed significantly in June 2026.
This article explains how commercial EPC ratings are calculated, how solar PV affects that calculation, what the current and incoming compliance requirements look like, and what the EPC uplift from solar realistically means for different property types.
How is a commercial EPC rating calculated?
Commercial properties in the UK are assessed using the Simplified Building Energy Model (SBEM), a calculation methodology developed by the Building Research Establishment (BRE). Unlike domestic EPCs, which are based primarily on running costs, commercial EPCs are based on carbon emissions. The rating reflects how much CO2 per square metre per year the building is estimated to produce in operation.
The SBEM calculation produces two key figures:
Building Emission Rate (BER): the calculated carbon output of the building as designed or assessed, measured in kgCO2/m2/yr.
Target Emission Rate (TER): a reference figure set by the government as the benchmark for a notional equivalent building.
The EPC band is determined by where the BER sits on a scale from zero to 150+. A score of zero represents net-zero carbon performance. A score above 150 is very poor. The assessment covers the energy used for heating, cooling, ventilation, and lighting. On-site solar generation is credited against the building's calculated energy demand, therefore reducing the BER directly.
The assessment must be carried out by a qualified non-domestic energy assessor. SBEM calculations for new buildings and certain existing buildings are carried out to Level 4 or Level 5 depending on the complexity of the building's services.
Commercial EPC vs domestic EPC: a critical difference Domestic EPCs use SAP (Standard Assessment Procedure) and are scored primarily on estimated energy costs. Commercial EPCs use SBEM and are scored on CO2 emissions. The same solar installation affects these two calculations differently. In a domestic assessment, the benefit partly depends on whether the meter is export-capable. In a commercial SBEM assessment, all on-site solar generation is credited against the building's carbon output, because the methodology treats it as displacing grid electricity in the model. This means solar tends to have a more direct and predictable impact on commercial ratings than on domestic ones. |
How does solar PV improve a commercial EPC rating?
Solar panels improve a commercial EPC by reducing the Building Emission Rate. SBEM calculates the building's energy demand across all modelled uses, then subtracts the electricity generated on-site by solar PV. That reduction in net grid energy consumption translates directly into a lower carbon figure, because the carbon intensity of grid electricity is built into the model.
Every kilowatt-hour of solar generation credited in the SBEM calculation reduces the building's BER. The size of that reduction depends on two things: the system's generating capacity relative to the building's modelled energy demand, and the carbon factor applied to grid electricity in the current methodology.
In practical terms, the BER reduction from solar is proportional to how much of the building's calculated energy use the panels can offset. A large roof array on a building with modest modelled demand will move the BER more than a modest array on a building with high heating and cooling loads.
What EPC band improvement can a commercial building expect?
Based on assessments across different commercial building types, a well-specified commercial solar installation typically delivers 1 to 3 EPC band improvements. For an office building or warehouse currently rated EPC D, a solar installation sized appropriately for the roof and the building's modelled demand can move the property to EPC B in a single intervention, according to analysis by EC Eco Energy and CCA Environmental based on UK commercial assessments.
The variation depends on:
The size of the solar system relative to the building's floor area and modelled energy use
The existing EPC rating: buildings rated E, F, or G see proportionally larger gains, as there is more headroom to improve
Whether the building's primary energy loads are electricity-intensive (where solar has direct impact) or dominated by gas heating (where solar has less direct effect)
Roof orientation, pitch, and available area, which determine achievable system size
For heavily gas-dependent buildings, solar alone may not be sufficient to reach EPC B. In those cases, solar is typically combined with LED lighting upgrades, improved controls, or low-carbon heating to achieve the required band. A qualified energy assessor can model the combined effect before any works begin.
Does the EPC assessor need documentation of the solar system?
Yes, and this matters for system design. When a solar installation is submitted to the assessor with proper documentation, including the MCS certificate, system capacity in kWp, roof orientation, and panel specifications, the assessor can enter precise figures into SBEM. Without that documentation, the assessor falls back on default assumptions built into the software, which typically undervalue modern high-efficiency panels.
The SBEM default assumes 120W per square metre of panel area, oriented south at 30 degrees with modest overshading. Modern panels commonly deliver 225W per square metre or more. An installation without documentation will be assessed at roughly half the actual output. Always ensure the MCS certificate and full system specification are provided to the energy assessor.
What the June 2026 MEES update means for commercial landlords
On 18 June 2026, the government published its long-awaited interim response to the Minimum Energy Efficiency Standards consultations for non-domestic buildings. The key findings for commercial property are summarised below.
June 2026 MEES interim response: confirmed positions Current minimum remains: EPC E for all rented non-domestic buildings in England and Wales. F and G rated buildings cannot be legally let. New requirement confirmed: From 2031, all privately rented commercial buildings with a floor area above 1,000 square metres must achieve EPC B, where cost-effective. Smaller buildings: Properties at or below 1,000 square metres are not subject to the EPC B requirement. The minimum standard for these remains EPC E. Interim EPC C milestone dropped: The previously proposed 2027 EPC C interim target has been removed and will not be taken forward. Secondary legislation still required: The EPC B requirement for larger buildings becomes law only once secondary legislation passes Parliament. Final penalty levels and exemption details are still to be confirmed. Source: Mayer Brown, Baker McKenzie, and Rhino Energy, July 2026, reporting on the government's June 2026 interim response. |
For owners of larger commercial buildings, the practical implication is clear. Buildings over 1,000 sq m that are currently below EPC B have until 2031 to improve, subject to cost-effectiveness. That is not a distant deadline. Commercial upgrade programmes involve surveys, planning, contractor procurement, potential tenant liaison, and G99 grid connection applications for solar. For buildings that need significant improvements, five years is not a long runway.
For buildings under 1,000 sq m, the legal minimum remains EPC E. But the market is already ahead of the regulation. Institutional investors, large corporate tenants, and ESG-focused occupiers are increasingly selecting buildings on green credentials, not just legal compliance. A property sitting at EPC D or E in an occupier market where competitors are offering B and C will face pressure on voids, rents, and long-term capital value regardless of what the minimum standard says.
CBRE estimates that 58% of London office stock by floor area currently sits below EPC B. The scale of upgrade work required across the UK's commercial property sector is substantial, and supply chain capacity will tighten as 2031 approaches. Contractors able to design and install commercial solar systems, carry out G99 applications, and commission at scale are already stretched in parts of the country.
Which commercial buildings benefit most from solar for EPC improvement?
Solar delivers its strongest EPC uplift for commercial buildings where the modelled electricity demand is significant relative to the available roof area, and where the existing rating is low enough that there is headroom to improve substantially.
The buildings that consistently see the largest EPC band movement from solar are:
Warehouses and logistics facilities: large roof areas relative to floor area. Even a modest solar system can offset a significant proportion of the modelled electricity demand. Buildings rated E, F, or G often reach B or C with solar alone.
Manufacturing facilities: high electricity consumption makes solar generation proportionally more impactful in the SBEM calculation. Combined with the commercial case for energy cost reduction, this makes solar one of the strongest upgrade options available.
Cold storage: refrigeration loads are electricity-intensive and run continuously. SBEM models this demand, and solar generation directly offsets it in the calculation.
Retail units with significant roof area: often rated D or E due to lighting and HVAC loads. Solar can frequently deliver a two-band improvement in a single project.
Office buildings with flat roofs: flat roofs allow panel orientation to be optimised. Buildings with poor fabric performance may need solar combined with other measures to reach EPC B.
Buildings where solar alone is unlikely to deliver EPC B: older buildings with predominantly gas heating and poor fabric performance, where the heating demand dominates the BER. In these cases, the pathway to EPC B typically requires a combination of solar, lighting upgrades, and a shift toward low-carbon heating. An energy assessor should model the package before any works are committed to.
EPC improvement routes for commercial buildings: solar versus alternatives
Improvement measure | Typical EPC impact and considerations |
Commercial solar PV | 1 to 3 band improvement. Direct BER reduction. Often the highest-impact single measure per £ invested for electricity-intensive buildings. |
LED lighting upgrade | 0.5 to 1 band. Lower cost. Often combined with solar for cumulative effect. |
Roof or wall insulation | 0.5 to 1.5 bands for poorly insulated buildings. High disruption. More impactful for heating-dominated buildings. |
Building management system (BMS) upgrade | 0.5 to 1 band. Depends heavily on existing control quality and building type. |
Air source or ground source heat pump (replacing gas) | 1 to 3 bands. High capital cost. Most impactful for gas-heavy buildings where solar alone is insufficient. |
Battery storage (alongside solar) | Incremental improvement to self-consumption. Not independently assessed in current SBEM but improves the operational carbon position beyond EPC measurements. |
Solar + LED combined | Often 2 to 4 bands. The most cost-effective compliance pathway for warehouse and logistics buildings. |
How is the EPC methodology changing, and does that affect solar's value?
Two methodology changes are relevant for commercial property owners planning solar now. The first has already happened. On 15 June 2025, the government overhauled the EPC assessment methodology for existing buildings, updating it to better reflect on-site generation, battery storage, and modern heat technologies. Solar PV now carries greater weight in the scoring framework than it did under the previous methodology.
The second change is in progress. In January 2026, the Department for Energy Security and Net Zero confirmed that four new headline metrics will be added alongside the carbon rating in a further reform: energy costs, fabric performance, smart readiness, and heating system efficiency. These are expected to be introduced in the second half of 2026 for non-domestic buildings. Solar PV, battery storage, EV charging, and heat pumps all score more strongly under the incoming methodology than they did previously.
The direction of both methodology changes is the same: on-site renewable generation, and solar in particular, is becoming more valuable in EPC calculations, not less. Buildings that install solar now will benefit from the uplift under the current methodology and be well-positioned under the incoming one.
One planning consideration: if an existing commercial EPC was issued before the June 2025 methodology update, it may understate the EPC benefit of solar. A qualified energy assessor can run a pre-installation SBEM model under the current methodology to show the expected uplift before any investment is committed.
How Eden Sustainable approaches EPC-driven solar projects
Not every commercial solar project is driven by EPC compliance. Most of our clients come to us primarily on the commercial case: energy cost reduction, carbon reporting, and the financial model. But EPC improvement is a consistent secondary benefit, and for some property clients, particularly those with letting obligations or imminent portfolio refinancing, it is the primary driver.
Our approach in either case is the same. Before any proposal is signed off, we can work with a qualified energy assessor to model the SBEM impact of the proposed system. That modelling shows the client the expected BER reduction, the resulting EPC band, and whether additional measures are needed to reach a specific target. It also confirms what documentation the assessor will need from the installation, so the MCS certificate and system specification are captured in the right format from day one.
We have delivered solar projects across warehousing, manufacturing, food production, cold storage, commercial property, and education. In each sector the relationship between system size, building energy profile, and EPC outcome is different. The only reliable way to know what a specific system will deliver on a specific building is to model it. We are happy to do that as part of an initial site assessment, with no obligation.
Frequently asked questions
Does the EPC rating improve automatically after solar panels are installed?
No. The EPC is a modelled assessment, not a live measurement of actual performance. After installation, the property owner needs to commission a new EPC from a qualified non-domestic energy assessor. The assessor enters the solar system details into the SBEM calculation and issues an updated certificate reflecting the BER reduction. You should provide the MCS certificate, system capacity, orientation, and panel specification to ensure the assessor can use precise figures rather than default assumptions.
How long does a commercial EPC remain valid?
A commercial EPC is valid for ten years from the date of issue. For properties that have had solar or other energy improvements since the last assessment, it may be worth commissioning a new EPC before the ten-year expiry if the updated rating would affect lettability, asset value, or financing. An EPC issued before June 2025 will have been calculated under the previous methodology and may understate the current rating.
Can solar alone get my commercial building to EPC B?
For many warehouse, logistics, and manufacturing buildings, yes. These building types have large roof areas relative to floor area and electricity-intensive loads that solar directly offsets in SBEM. For buildings where gas heating dominates the energy profile, solar alone is unlikely to be sufficient. The path to EPC B for those buildings typically requires a combination of solar, LED lighting, and a low-carbon heating strategy. A pre-installation SBEM model will show which combination is needed and at what cost.
Does the MEES EPC B requirement apply to owner-occupied commercial buildings?
No. MEES applies to privately rented non-domestic buildings. Owner-occupied commercial property is not subject to the minimum letting standard. However, the EPC rating still affects asset value, green finance eligibility, and the building's attractiveness to future purchasers or tenants. Many owner-occupiers are investing in EPC improvement ahead of potential letting or sale, and because the financial case for solar stacks up independently of the compliance question.
Does adding battery storage improve the commercial EPC rating further?
Under the current SBEM methodology, battery storage does not independently improve the commercial EPC rating in the same direct way that solar generation does. Battery storage improves the operational self-consumption of solar generation, which benefits the business commercially, but the SBEM calculation credits solar generation at the point of production rather than at the point of consumption. The incoming methodology changes, expected in the second half of 2026, are expected to give greater weight to smart readiness and storage, which may improve how battery storage is treated in future assessments.
What happens if my commercial building fails to meet MEES requirements?
For the current EPC E minimum, non-compliance means the property cannot be legally let or have a lease renewed in England and Wales. Penalties are based on rateable value and can reach up to £150,000 per property, with the breach published on the PRS Exemptions Register. For the incoming EPC B requirement for buildings over 1,000 sq m from 2031, the government has confirmed it is reviewing penalty levels and enforcement powers as part of the next stage of reform. Final figures are not yet confirmed.
Find out what solar would do to your building's EPC rating
If you own or manage a commercial property and want to understand the EPC uplift a solar installation would deliver, we can arrange a pre-installation SBEM model for your site. The modelling shows the BER reduction from the proposed system, the expected EPC band outcome, and whether any additional measures are needed to reach a specific target.
Contact Eden Sustainable at edensustainable.co.uk or call us to speak with a member of our commercial team.
