Solar And Batteries For New Builds

Building a new home? Here’s what to consider when planning for solar—from pre-wiring and roof design to battery readiness and passive house considerations.

Written by

Paul Hollingsworth

Published on

October 27, 2021

Introduction
Solar Pre Wiring
Battery Pre Wiring
Cabling/Monitoring
What To Consider at Design Phase
Passive House Or Airtight House

Introduction

Solar is something most people think about when building. If you or someone you know is building new, it makes sense to start thinking of your home’s energy needs.Let’s run through what you should think about when it comes to solar for your new house.

Solar Pre Wiring

If solar is not in the budget just yet, pre-wiring can save installation costs and unsightly external cabling down the track.

Any pre-wire we do will then be deducted from the cost of the future installation.

"Solar Ready"– A Note Of Caution

Some of our customers have come to us excited that they did the hard work during their build and got the electrician to pre-wire for solar. Unfortunately, more often than not, the wiring is incorrect – it’s not enough to run an AC cable into the roof space.

We can just as easily come and do it for you, or talk with your chosen electrician about how they can get it done once, and done right.

Battery Pre Wiring

Battery pre wires are a bit trickier. To pre-wire for a Tesla battery, for example, requires specific cabling.

To make the Tesla battery look the part, it pays to get the cables in the right positions first time. Call us for this one!

Each battery system requires different wiring. If you are not sure which battery system you will go for in the future, then we suggest leaving an area free near your switchboard. This will ensure a battery system can be easily wired in the future.

Cabling/Monitoring

A garage or outbuilding is sometimes the best place to locate solar panels. Most of the time outbuildings are not easy to wire to post build.

This is especially true if you are looking at a battery as part of your installation. Due to batteries providing backup power, you need to make sure there are the correct cables for backup functionality. Especially if the best location for the battery is in a separate building like a garage.

What To Consider At Design Phase

The best time to think about solar for your new build is during the design stage. There are tweaks that can make your house much more suitable, save you money and make you much happier with your system.

Roof Angle And Aspect

With the latest solar technology, the angle and aspect of your roof are less critical, however, if you’re able to design your roof right, there are benefits to be had.

The Sun’s path changes throughout the year(Download the Lumos app to check it out in augmented reality), therefore certain roofing orientations work better than others at different times of the year.

East/West aspects work better in Summer and Northern aspects work better in Winter. Any orientation from East through West is good.

Angles between 10º- 50º work well. The steeper the angle, the more energy you will produce in Winter. At angles above 10º solar panels will self clean during rain.

If your roof is 10º or lower, solar will work better by tilting the panels to a steeper angle. Tilting involves extra racking equipment and cost. If it’s an option to steepen your roof up at the design stage, then go with that.

Roofing Type

You can fix solar to almost any roofing type, but while you have the choice you can save money by choosing one that doesn’t require extra fixing for solar.

Roofing types that require no extra fixing:

Corrugate
5-Rib
Decramastic tile

Roofing types that require extra fixing:

Standing seam (alpine tray)
Tile
Slate
Solar – rib (this profile is not designed for solar panels)

Flue & Chimneys

Half cell technology and Fronius’ new MPPT algorithm means that shading is not the solar killer it used to be. Partial shade on panels is now manageable.

In saying that, it is worthwhile to limit shading if possible. Keep roof penetrations such as vents, chimneys and flue’s away from roof aspects that can be utilised for solar.

When thinking about the layout of the house, it might be tempting to position your fire on the northernmost side, however, the chimney or flue will likely be right in front of your solar panels.

If possible arrange your lounge, so that the chimney or flue comes out of the south side of the roof. Or at least high up on the north side, allowing room for panels below.

Purlins/Fixing

On a tin roof, solar panels fix to the roof purlins. Designing solar to be part of your build ensures these fixings can be put in the best place for the solar panels.

Passive House Or Airtight House

You may be building an energy efficient home or passive house. These homes generally have an airtight layer to prevent heat loss.

As part of your solar installation, you will likely need to penetrate the roof for the solar cabling. The Key is to get in early.

To avoid any air leaks your roof penetrations are best done during the build stage. This way we can seal up the penetration to maintain the airtightness, you don’t want to fail your blower door test!

Roof penetrations on an existing airtight home are doable, but more care needs to be taken to maintain the airtightness.

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