Office Solar Case Study
Edinburgh New Town law firm — listed building 95 kWp install
Edinburgh New Town law firm — listed building 95 kWp install
A long-established Edinburgh law firm occupying a Grade II* listed Georgian townhouse in the New Town World Heritage Site needed to address looming MEES regulations and growing client Scope 2 disclosure demands. The building footprint was small (1,800 sqm net internal area) and obviously heritage-sensitive. We designed a 95 kWp install split across concealed rear-roof areas and a single-storey rear extension, with full Heritage Impact Assessment and pre-application consultation with Edinburgh City Council heritage officers.
The numbers
| Metric | Value |
|---|---|
| System size | 95 kWp (concealed rear-roof + outbuilding) |
| Panel count | 175 |
| Annual generation | 87,000 kWh/year |
| Annual saving | £28,000/year |
| Simple payback | 6.8 years |
| Annual CO₂ saved | 20 tonnes |
| EPC uplift | D → C (7-point gain) |
| Completion | Q1 2026 |
Heritage planning: the challenge and the solution
Grade II* listing in the Edinburgh World Heritage Site meant the standard Permitted Development route was unavailable regardless of system size. Listed Building Consent (LBC) was required for any works affecting the character of the listed structure, in addition to a pre-application consultation with Edinburgh City Council’s conservation officers and Historic Environment Scotland (HES).
The key to securing LBC on a building of this sensitivity was the concealed installation strategy. We proposed placing all panels on rear-facing roofslopes not visible from any public vantage point, combined with a south-facing outbuilding roof at the rear of the garden court. A Heritage Impact Assessment (HIA) was prepared in line with HES’s Managing Change in the Historic Environment guidance, demonstrating that the installation would have no adverse impact on the significance of the listed building or the Outstanding Universal Value of the World Heritage Site.
Pre-application advice from the council’s conservation team confirmed this approach was acceptable in principle. The formal LBC application was submitted with the HIA, proposed panel specification, colour specification (anthracite frames matching existing roof details), and structural calculations showing zero roof penetration on the main building. LBC was granted unconditionally in 11 weeks.
Project approach
With only 1,800 sqm of net internal area and heritage constraints limiting roof coverage to concealed rear zones, the system size ceiling was around 100 kWp. We sized to 95 kWp to maximise generation within the consented zone while staying below the G98/G99 threshold — avoiding a formal DNO grid application and its associated 11-week minimum lead time.
Half-hourly meter data pulled from the firm’s DNO showed a clear daytime demand profile characteristic of professional services occupancy: peak consumption between 09:00-18:00 Monday-Friday, moderate HVAC and IT baseload overnight. PVSyst modelling for Edinburgh’s latitude (55.9°N) confirmed an 87,000 kWh/year generation estimate with a self-consumption ratio of 82% — high for a system of this size, reflecting the matched daytime demand profile.
Finance was structured on a 10-year operating lease, keeping the asset off the balance sheet under FRS 102. Monthly lease payments of £1,800 were offset against month-one bill savings of £1,950, achieving cash-flow positivity from the first statement.
Roof, structural, and electrical
The rear roofslope is 19th-century slate over timber rafter-and-purlin construction. Structural assessment confirmed adequate load capacity for lightweight aluminium in-roof mounting — panels sit flush with the slate line, preserving the roofline silhouette when viewed from the garden. A separate assessment was carried out for the flat-roofed outbuilding, where lightweight ballasted frames were used.
String cabling was run internally down the rear elevation in mini-trunking, connecting to a single 95 kW inverter installed in the building’s basement plant room. The cable route avoided all principal rooms and maintained the character of the main staircase. Grid connection was G98 notification only, submitted to SP Distribution (Scottish Power) three weeks ahead of commissioning.
Compliance, EPC and reporting
The system was installed to MCS Commercial standards with NICEIC electrical certification. Commissioning followed IEC 62446 with full string IV-curve records. Post-commissioning EPC re-assessment under SAP 10.2 confirmed a D → C uplift — a meaningful improvement, though the listed building’s solid-wall fabric means a higher EPC band requires additional fabric intervention beyond solar’s scope. For the firm’s reporting, we provided location-based and market-based Scope 2 calculations, SECR-ready narrative, and CDP text covering the solar installation.
What the customer said
“We feared planning would be impossible on a Grade II* listed building. The concealed rear-roof design got Listed Building Consent in 11 weeks. The system has been completely invisible from any public viewpoint.”
Could your listed office building deliver similar results?
Heritage context doesn’t preclude solar — it changes the planning route and constrains the installation design. We have secured Listed Building Consent or Conservation Area consent on 23 commercial projects since 2020, with a 78% first-application approval rate. The economics on listed buildings are typically 15-25% longer payback than equivalent unrestricted buildings, reflecting the higher design and planning overhead, but the EPC uplift and Scope 2 reduction are equivalent.
The fastest way to understand what’s possible on your listed or heritage-sensitive building is a free desk feasibility. Send us any existing planning history, your half-hourly meter data, and a roof plan. We’ll confirm the consent route and return a costed proposal within 7 working days.