Before commissioning a full site survey, use this checklist to assess the solar potential of your commercial roof. Developed by Caledonia Solar’s design team based on hundreds of Scottish commercial roof assessments.
Before commissioning a full site survey, use this checklist to assess the solar potential of your commercial roof. Developed by Caledonia Solar’s design team based on hundreds of Scottish commercial roof assessments.
WHAT IT COVERS
Roof structure and age — what makes a roof suitable or unsuitable
Orientation and pitch — how much it affects generation
Shading assessment — the 10 most common causes and how they affect output
Available area — how to calculate usable roof space
Structural loading — what to ask your structural engineer
Grid connection — preliminary checks before the DNO application
Planning status — quick check for permitted development eligibility
Roof condition — what needs to be resolved before installation
Roof access — installation and ongoing maintenance requirements
Lease and ownership — what needs to be resolved before committing
TRUST LINE
Used by Scottish commercial property managers, operations directors and facilities teams before commissioning a full solar survey.
Full 10-point checklist. Each point: title, brief explanation, yes/no/unsure assessment field, notes field. Designed for the facilities or operations manager to complete during a roof walkthrough.
CHECKLIST POINT 1: ROOF ORIENTATION
South-facing roofs produce maximum solar output in Scotland. East and west-facing roofs produce approximately 15–20% less. North-facing roofs are not suitable for solar. ASSESSMENT: What direction does your main roof face? South → Excellent. East/West → Viable with reduced output. North → Not suitable.
CHECKLIST POINT 2: ROOF PITCH
Flat roofs (0–10°) are excellent for solar — panels are mounted at an optimised angle using ballasted frames. Low-pitch roofs (10–30°) are good. Steep roofs above 40° require specialist mounting and increase installation cost. ASSESSMENT: Is your roof flat, low-pitch or steep?
CHECKLIST POINT 3: ROOF AREA
A commercial solar system requires approximately 6–8m² per kWp of capacity. A 100kW system needs approximately 600–800m² of usable roof area. Deduct areas occupied by rooflights, plant, lift shafts and access routes. ASSESSMENT: What is the total usable roof area in m²?
CHECKLIST POINT 4: SHADING
Shading from neighbouring buildings, parapet walls, plant equipment and rooflights reduces solar output. Even partial shading on one panel can affect the output of an entire string if the system is not correctly designed. ASSESSMENT: Are there any significant shading sources within 45° of south visible from the roof?
CHECKLIST POINT 5: ROOF CONDITION AND AGE
Solar panels have a 25–30 year lifespan. If the roof will need replacement within 10–15 years, panels will need to be removed and reinstated at additional cost. A roof condition survey is recommended before solar installation if the roof is over 15 years old. ASSESSMENT: Has the roof been inspected in the last 5 years? Approximate age of roof covering?
CHECKLIST POINT 6: STRUCTURAL LOADING
Ballasted flat-roof solar systems add approximately 15–25 kg/m² of dead load to the roof structure. The roof’s structural capacity must be confirmed by a structural engineer before installation. Most modern industrial and commercial roofs can accommodate this load. Older structures may require assessment. ASSESSMENT: Has a structural engineer reviewed the roof loading capacity?
CHECKLIST POINT 7: PLANNING STATUS
Most commercial rooftop solar in Scotland benefits from permitted development rights under the May 2024 reforms. Exceptions: listed buildings, buildings in conservation areas, some agricultural buildings. ASSESSMENT: Is the building listed? Is it in a conservation area? Any planning restrictions noted on the title?
CHECKLIST POINT 8: GRID CONNECTION
Commercial solar systems above 16A per phase require a G99 application to the DNO. Larger systems may require DNO assessment of local grid capacity. Existing grid connection size determines the maximum solar export capacity. ASSESSMENT: What is the existing grid connection size (kVA or amps)? Who is your DNO — SP Energy Networks or SSEN?
CHECKLIST POINT 9: ROOF ACCESS
Installation requires safe access to the roof for workers and equipment. Ongoing maintenance requires periodic roof access for inspection. ASSESSMENT: Is there safe, established access to the roof? Is there a roof access plan in place? Any height or access restrictions?
CHECKLIST POINT 10: TENURE AND OWNERSHIP
The solar installation must be compatible with the building ownership and lease structure. For leasehold properties, landlord consent is required. For short leases, a PPA or finance term shorter than the lease remaining may be required. ASSESSMENT: Do you own or lease the building? If leasehold, how long is the remaining term? Is landlord consent required?
CHECKLIST NEXT STEPS
If you have answered Yes or Viable to 7 or more of the above points, your building is likely to be a strong candidate for commercial solar. Contact Caledonia Solar at a.jones@caledoniasolar.co.uk or 07766 906 262 to arrange a free initial consultation and site assessment.