Best Practice Guidelines for Integrating Photovoltaics into Building Design

In this article we share the principles we use when collaborating with design teams to deliver maximum value when integrating solar.

Good solar integration begins at the concept stage. By treating the roof as a functional energy asset rather than just a weather shield, architects can blend architectural form with engineering function.

Whether you're designing for immediate installation or preparing buildings to be solar-ready, early engagement with specialist solar designers ensures better outcomes for your clients and your projects.

1. Enhancing Value through Simplified Form

The form and layout of the roof have the single greatest impact on a PV system's potential. We see many designs featuring complex, fractured roofscapes that force PV arrays to be split into small, inefficient sub-groups.

Design Strategy:

Simplify the Geometry: Aim for large, uninterrupted roof planes. Complex angles and hips reduce usable space and complicate installation.
Form Follows Function: Prioritize a roof design that optimizes solar access. A simplified roof form not only maximizes energy yield but often results in a cleaner, more deliberate architectural aesthetic when panels are installed.
Avoid Fragmentation: Ideally, arrays should be grouped together rather than scattered. Fragmented or irregular roof shapes often force the use of smaller sub-arrays, which increases installation complexity and costs while reducing the available generation yield. In addition, continuous and symmetrical configurations generally provide a more pleasing architectural appearance.

2. Orientation and Yield

While true north is the standard for maximum total energy generation, modern usage patterns allow for flexibility in orientation.

North Facing: Ideal for maximizing specific yield (total kWh generated per kWp installed).
East/West Split: Arrays facing East and West are viable and often beneficial. While they may generate slightly less total energy than North-facing arrays, they produce power earlier in the morning and later in the afternoon, better matching the peak consumption periods of residential and commercial buildings.

3. Tilt Angles and Self-Cleaning

The angle of the array impacts both energy production and long-term maintenance.

Ideal Pitch: For pitched roofs in New Zealand, a pitch of 20° to 30° is near optimal for year-round generation.
The 10° Rule: A minimum tilt of 10° is recommended to ensure panels self-clean via rainfall. While frames can be used to tilt panels on flatter roofs, this increases installation complexity and cost. Arrays flatter than 10° accumulate dirt and lichen more quickly, significantly reducing performance and increasing maintenance costs.
Commercial Flat Roofs: On large flat roofs, a 10° tilt strikes the best compromise. This angle minimizes inter-row shading to maximize total roof yield. Steeper tilts improve per-panel generation but significantly increase wind loading, often requiring expensive roof strengthening.

4. Managing Shadows

Shading is the enemy of solar performance. Because PV modules are connected in series strings, shading on a single panel can disproportionately reduce the output of the entire array. Localised shading on single cells can create hot spots that lead to accelerated degradation, resulting in long-term failures and safety issues.

The "Keep Clear" Zone: Design the roof to avoid structures or equipment that cast shadows on North-facing surfaces.
Vertical Obstructions: Be mindful of parapets, chimneys, lift overruns, satellite dishes, and flues. Even thin shadows from aerials or poles during peak sunlight hours (9 am – 3 pm) can dramatically reduce system performance.
Vegetation: Consider the mature height of landscaping and trees to ensure long-term solar access.

5. Aesthetics and Integration

A well-integrated system looks intentional.

Flush Mounting: For pitched roofs, flush-mounted arrays generally detract less from the building's appearance than tilted frames and experience lower wind loading.
DC Cable Routing & Safety: High-voltage DC solar cabling presents a specific fire risk due to arcing. We recommend routing DC cables externally to keep this risk outside the building envelope and facilitate maintenance. To minimise the visual impact of external runs:

Specify UV-resistant conduits or aluminium cable tray with a lid.
Plan routes that follow natural building lines or are screened from view, rather than hiding them inside the roof cavity.

Inverter Placement: Inverters require a cool, secure, and accessible location. They can produce operational noise, so they should be positioned away from primary living areas or quiet zones. Most inverters should be protected from direct sunlight.
Reflectivity: PV panels have an anti-reflective coating and are less reflective than glass or some roof finishes. For sensitive locations, orientation and tilt may need to be adjusted to manage glint and glare.

**Auckland Airport Transport Hub**
- Simplified yet elegant form supports maximum yield.
- Tilt mounted for roof self-cleaning (5° tilt + 5° roof pitch).
- Safe access between all rows for maintenance and cleaning.

6. Maintenance and Safety

Consider the longevity of the system: PV arrays are durable assets that will occupy the roof for 30 years or more, requiring long-term structural and maintenance planning.

Safe Access: Include safe access points for installers and maintenance personnel. Panels should be spaced away from the roof edge.
Walkways: Avoid designing a "sea of glass." Arrays should be separated into sub-groups (no more than 3 modules deep) with walkways (>0.5m) between them to allow for cleaning and maintenance access.
Tilted Modules for Roof Cleaning Access: Ensuring long-term access to the roof cladding is critical. Tilted panels are advantageous, as the frame clearance allows for washing underneath the modules, while the array layout naturally creates defined rows for safe movement.
Drainage: Ensure the array layout does not impede natural drainage channels or gutters.
Fall Arrest Design & Co-ordination: Fall arrest systems are frequently overlooked in early planning. Integrating these systems with the PV design avoids late-stage conflicts, which can lead to poor safety outcomes and compromised system performance or design changes.
Skylights: Avoid placing panels over skylights. If the skylight is not trafficable, a walkway between the skylight and PV panel should be allowed.

7. Structural Considerations

Solar arrays introduce additional static and dynamic loads that must be integrated into the primary structural design to ensure long-term safety and performance.

Load Capacity: The roof structure must be designed to accommodate the 'dead weight' of the PV system (typically 10–20 kg/m²) alongside expected seismic loads.
Wind loads: Beyond gravity loads, the PV array may also increase the wind loading. The loads change from a distributed load to point loads where the fixings attach to the roof structure or cladding.
Corner Zones: On larger buildings in high wind zones, utilizing corner and edge zones for PV is often impractical. These areas experience the highest wind pressures, often making the required structural reinforcement uneconomical.
Fixing and Warranties: Mechanically fixed systems typically require roof penetrations, which can increase the risk of leaks and void warranties. Always seek confirmation from the roofing manufacturer that the specific mounting system intended for use is compatible with their product.

**Victoria University Ngā Mokopuna.**
*Boundary pushing solar architecture.*

8. Future-Proofing: Solar Ready Design

If budget constraints prevent immediate PV installation, a "Solar Ready" design minimizes future costs and disruption.

Pre-Wiring: Install conduit runs from the roof to the main switchboard location during construction.
Space Allocation: Designate wall space for future inverters and battery storage near the distribution board.
Structural Provision: Engineer the roof structure to accommodate the future load of solar panels now, avoiding prohibitive remedial reinforcement later.

Need expert advice on your next project? Revolve Energy partners with architects to model, design, and specify high-performance solar systems that respect your architectural vision.

Click here to Discuss Your Energy Vision with Us

Designing for Solar: A Guide for New Zealand Architects & Designers