How do you tell if your roof is suitable for solar?

You’d be surprised how often we hear: “I can’t get solar because my roof doesn’t face north” or “My roof isn’t suitable for solar”. And usually, that’s not accurate. There are very few roofs where solar won’t work.

Watch the video below for a full breakdown on how your roof can impact solar performance.

Here are some of the key things that will affect your solar performance:

Roof material

Let’s start with the easy bit – No matter your roofing material whether it’s corrugated, tile, rib roofed, 5-rib, alpine tray, or slate —we have a tried-and-tested method to attach solar panels to your roof. We work closely with manufacturers and suppliers to ensure all fixing methods are approved for use in NZ and won’t impact your roof’s integrity.

Flat roof

The good news is there is a solution for solar on flat roofs.

For new builds, we work with the roofing membrane manufacturer or roofing contractor to install suitable fixings during the build process. 

If it’s an existing home, we can use a ballast system. This uses the weight of the structure to ensure we don’t need to make any new penetrations to the roof.

Roof orientation

A common myth is that solar only works if your roof faces north. While it’s true that north-facing panels produce the most total energy, roofs facing east or west will still produce about 85% of what a north-facing roof would.

Ten years ago, when solar panels were more expensive and less efficient, having a north-facing roof was key. Today, that’s not the case. Now, solar panels can be installed on multiple roofs, all working together to power your home. East and West arrays can help to create a useful energy curve throughout the day.

Roof pitch

Another factor affecting performance is the pitch of your roof. Panels produce the most energy when the sun’s light hits them directly. 

In summer, when the sun is higher in the sky, flatter panels work better. In winter, when the sun is lower, steeper panels perform better. 

A 15º-45º roof will give you the best year-round performance. If needed, we can use tilt frames to adjust your panel’s pitch.

System Type

If you install solar only, it’s important to understand when you need power most throughout the day, as this affects which parts of your roof may be best to install on.  East-facing panels produce more energy in the morning, North produces the most in the centre of the day and West produces more in the afternoon. 

Installing solar with a battery shifts the focus to maximising production since you can store excess power to use later, making it less important when the power is produced.

Roof Size

The main factor that will impact how much power your solar system will produce is the size of your roof.

Usable space isn’t just about how big your roof is. We also need to take into consideration factors like chimney flues, skylights and satellite dishes that can cause shading on your solar array. 

However, we find most homes have suitable roof space to accommodate the number of panels they need. 

An alternative: Ground Mount Array

If your roof isn’t suitable for solar, another option is a ground-mount solar array. 

The benefit of a ground mount is the flexibility – you can choose the location, the angle to North, and the pitch of the panels to suit your needs.  

However, this option adds extra cost due to the framework needed to mount the panels and the extra cabling to send the power back to the home. 

So, how do we know what your roof will produce?

After considering all these factors, how do you know how a solar system on your roof will perform and how much power you can produce?

Every system we design is modelled using a programme that maps your property’s location, so we know the sun’s path throughout the year. This paired with weather data for your local area and your roof’s orientation and pitch means we can accurately predict the amount of power you will be able to produce.

Ready to see how a solar system will perform on your roof? Contact us to book a site visit today.