Purpose

This post sets out what DesignDevise (DD) does—and does not do—under common solar engagements. It also records the Client’s responsibilities for the base building. Solar is a secondary installation; it must not proceed on a compromised or unverified structure.

1. Existing Building Assessment (without Solar Panels)

Status

Not included in our standard solar engagements and generally not offered under a solar scope. A standalone building assessment requires inspections, condition/defect review, load rating and a formal report. This is outside our solar design remit.

Client responsibility

Solar panels are secondary elements and must only be installed on buildings that are structurally serviceable and within their intended design life. By proceeding with a solar installation, the Client is representing that the base structure is fit for purpose.

If there are pre-existing issues (e.g., corrosion, cracking, section loss, damaged fixings, or unauthorised alterations), the proper sequence is to first assess and rectify the building before considering solar. If this step was skipped, the Client should question how solar feasibility was considered without also considering building feasibility. Our solar scope does not extend to cataloguing or resolving pre-existing building deficiencies.

2. Racking-Only Assessment

What we do

• Design and certify the racking system only (rails, fixings, feet, clamps, etc.) for load combinations in accordance with AS/NZS 1170.0 / 1170.1 / 1170.2 / 1170.3.
• Address seismic (per AS 1170.4 or NZS 1170.5) when requested.
• Provide per-zone wind pressures and reaction tables at fixings/supports so the Client’s engaged structural engineer can verify the adequacy of the roof members and supporting structure.

What we don’t do

• We do not assess the existing building (roof sheeting, purlins, rafters, trusses/frames, columns, connections, footings).
• We do not perform roof sheeting checks in any scope. For off-purlin solutions, we proceed only where the fastener manufacturer permits such fixing and supplies relevant test data; we rely on that data and do not independently verify it.

Typical certificate disclaimer

“Assessment of supporting roof(s) and structure(s) is excluded and must be checked by others. Client to engage a structural engineer.”

 

3. Racking + Building Assessment

What we do

• Everything in Racking-Only, plus a desktop design review of the roof framing and primary load path for the incremental PV effects (permanent actions, PV dead load, maintenance/installation live loads, wind per AS/NZS 1170.2, snow per AS/NZS 1170.3).
• Seismic checks (per AS 1170.4 or NZS 1170.5) are undertaken when specifically requested and are limited to the effect of the added PV system only.
• Elements typically reviewed: purlins, rafters, trusses, key connections and columns/walls.

What We Don’t Do

• Resolve or take responsibility for any underlying deficiencies in the existing building (including seismic, structural, or condition-related issues). These remain the Client’s responsibility to address under a separate engagement.
• Absorb liability for pre-existing defects such as corrosion, material loss, damage, or unauthorised modifications.
• Perform roof sheeting checks under concentrated point loads in any scope. For off-purlin solutions, we proceed only where the fastener manufacturer permits such fixing and provides test data; we rely on that data and do not independently verify it.

Critical Assumptions

• Condition & capacities: The existing structure is assumed sound, serviceable, and at full member capacity.
• Information reliance: Our design is based on drawings/data/checklists supplied by the Client, manufacturer, or installer; we do not independently verify unless separately engaged.
• Not a re-certification: This scope is not a re-certification of the existing building with solar panels installed and must not be relied on as such.

Typical certificate wording

“This assessment assumes that the existing structure(s) are capable of withstanding all applicable loads in accordance with current Australian Standards. It is also assumed that the roof structure is in generally good condition and has not been subject to significant loading or modifications.”

4. Example – Seismic Requests

Sometimes Clients ask us to “check seismic” for the solar panels under the Racking + Building Assessment. It is important to be clear that under a solar design scope we do not provide a full seismic assessment or certification of the entire building. That is a separate, much larger exercise, even if full structural drawings are available.

What we do is limited; we check the incremental effect of the solar panels on the main roof members (purlins, rafters, and key connections) under seismic load combinations, in accordance with AS 1170.4 (Australia) or NZS 1170.5 (New Zealand). This confirms only whether the additional solar loads materially change the behaviour of the roof system.

If the parent building itself has any underlying seismic deficiencies, those remain outside our scope and are the Client’s responsibility to identify and address under a separate building assessment. Our review of solar-related effects should not be taken as recertification or upgrade of the existing building for seismic compliance.