Is My Christchurch Roof Suitable for Solar?

Start with the roof you have

A roof does not have to face perfectly north to deserve a solar assessment. EECA considers direction, tilt, space, condition and shade together; one less-than-ideal feature does not automatically rule solar out. See EECA’s roof guidance.

For a Christchurch property, begin with three questions: which roof faces get clear sun, how much uninterrupted space do they offer, and will the roof need work soon? Those answers give an installer a better starting point than the floor area of the house.

Take photographs from a safe position on the ground. A homeowner’s first check should help prepare a quote request; the installer still needs to confirm measurements, structure and mounting.

North, east or west: ask for a layout comparison

EECA rates north, northeast and northwest favourably, and recognises east and west as useful options. South-facing roofs generally need closer scrutiny. A roof’s pitch and shade affect the outcome as well as its compass direction.

Request the forecast for the actual proposed layout. A generic “Christchurch system” estimate cannot tell you which side of your house is the better choice. Compare the options at the same equipment specification and with the assumptions visible.

Check when the shadow reaches the panels

BRANZ’s photovoltaic design guidance stresses the importance of avoiding year-round shade during the main generating hours. A roof that looks sunny in a summer listing photograph may have a different winter shadow pattern. Read the BRANZ photovoltaic design factsheet.

Note the trees, chimneys, neighbouring buildings and higher ground around the proposed array. If you can, photograph the same roof area in the morning, around midday and later in the afternoon, recording the date and time. Ask the installer to model seasonal shade rather than relying only on those photographs.

Have the quote identify any shade allowance in its forecast. If different equipment is proposed to manage partial shade, ask what improvement is expected for this particular layout and how it was estimated.

Port Hills properties need a view of the horizon

On a hillside, the roof direction and the surrounding slope are separate questions. A promising roof face can still lose sun behind higher ground or nearby trees. BRANZ’s site-orientation guidance explains why topography and surrounding obstructions need to be assessed at the site. See BRANZ on site orientation.

For a Cashmere, Huntsbury or other Port Hills property, ask whether the assessment includes the horizon as well as nearby objects. A photograph of the roof alone does not show what blocks sunlight from beyond its edge.

On a flat suburban section, give the installer the same information about mature trees and taller neighbouring buildings. Use the address and roof measurements to make the decision; a suburb name is not a suitability rating.

Usable roof space is smaller than the roof outline

A large roof can be split into small sections by hips, valleys, skylights and vents. Ask for a scaled panel layout showing the chosen panel dimensions, obstructions and access requirements. A panel count without a drawing is difficult to check.

BRANZ notes that mounting design needs to account for roof loads and wind uplift as well as keeping the roof watertight. These checks belong in the site assessment, especially where a roof is exposed or a design uses raised frames. See BRANZ’s PV installation guidance.

If two quotes fit very different numbers of panels, ask each installer to explain the layout. For capacity and household demand, use our system sizing guide.

Resolve roof work before committing to panels

Ask about roof age, leaks, corrosion and planned replacement before choosing an installation date. EECA includes remaining roof condition in its suitability assessment. Work that is already due should be discussed alongside the solar proposal.

Our metal and Colorsteel roof guide covers condition, fixings and warranty questions in more detail. For tile or membrane roofs, ask the installer to explain the proposed mounting method and who is responsible for weatherproofing.

Request a separate price for any roof repairs, access equipment or electrical work. That makes it easier to compare proposals without confusing roof preparation with the solar equipment itself.

Send this with your quote request

• Your address and any roof plans you already have.
• Ground-level photographs showing the roof and nearby obstructions.
• The approximate roof age, material and any known problems.
• Your electricity use and when people are usually at home.
• Plans for an EV, a battery, an extension or a roof replacement.

Ask the installer to return a panel layout, a generation forecast with shade assumptions, an itemised scope and any conditions that need checking on site.

A suitable roof is one part of the project. The connection still needs its own assessment. If the property is on Orion’s network, our Orion export and approval guide explains that step.