Aluminium vs Galvanised Steel Solar Inverter Covers: Which Lasts Longer?

Shop around for a solar inverter cover and you'll find two main materials: galvanised steel and aluminium. Steel covers are usually cheaper up front, so it's fair to ask what you actually get for the extra money with aluminium.

The short answer: an aluminium cover won't rust, weighs about a third as much on your wall, and is easier to live with. Here's the detail.

1. Rust: the big difference

Steel rusts. Galvanised steel is ordinary steel with a thin coat of zinc on the outside, and that zinc slowly wears away to expose the steel underneath. While the coating is intact, it does a good job.

The weak points are anywhere the coating has been cut or broken. On an inverter cover that's a lot of places:

• Every cut edge on every panel
• Every ventilation hole, slot or louvre
• Every screw and bolt hole
• Any scratch from assembly, a ladder, a lawnmower or a stray ball

A powder coat over the top helps, but once moisture gets in at a chip or edge, rust can creep underneath the paint and spread. Near the coast, salt in the air speeds all of this up.

Aluminium simply can't rust, because rust is iron oxide and aluminium has no iron in it. Marine-grade aluminium (5000 series) is alloyed with magnesium specifically to handle salty, wet conditions, which is why it's used to build boats. If it's scratched, it forms a thin protective oxide layer that doesn't spread or leave orange stains down your wall.

2. Weight on your wall

Aluminium is roughly one third the weight of steel for the same thickness. That matters when a cover is hanging off your wall for the next 10 or 20 years. A lighter cover puts less load on the wall fixings, is easier to lift into place by yourself, and is easier to take down when your installer needs access.

3. Heat

In direct sun, the colour and finish of a cover have the biggest effect on how hot its surface gets. A dark cover will run hotter than a light one, whatever it's made of.

Where the metal makes a difference is in how heat moves through it:

• Aluminium conducts heat about four times better than steel, so heat spreads out across the panel instead of building up in hot spots.
• A sheet of aluminium holds roughly a third less heat than a steel sheet of the same thickness, so it cools down faster once the sun moves off it.

Either way, the most important thing for keeping your inverter cool is airflow. Whatever cover you choose, make sure it leaves at least 30mm of space around your inverter and stays open enough for air to move through. Read more about why ventilation matters.

4. Getting to your inverter

You'll need to see your inverter's display from time to time, and your installer will need to reach the inverter and isolator switches during servicing. Some covers have to be unbolted or lifted off the wall entirely to do this.

Our inverter covers have a front panel that lifts open. Undo the thumb screws at the bottom, lift the panel, and you can read the display or reach your isolator in seconds, with no tools and without taking the cover off the wall.

5. The real cost over time

A cover is meant to protect an inverter that cost thousands of dollars. If a cheaper cover starts rusting after a few years, you're paying again for a replacement, plus the time to take the old one down. A rusty cover can also stain your wall and look worse than the bare inverter did.

An aluminium cover costs more up front, but it should last as long as your solar system does.

Quick checklist before you buy

• Material: Is it aluminium, or galvanised steel that can rust at cut edges and holes?
• Fit: Will it leave at least 30mm clearance around your specific inverter model?
• Access: Can you open it to read the display without taking it off the wall?
• Cabling: Is there room for conduits and isolator switches?
• Battery: If you have a home battery, is there a matching cover so your system looks consistent?
• Colour: Can you match it to your house?

Why we use marine-grade aluminium

Every Sunridge cover is made from 5000-series marine-grade aluminium and finished in Colorbond powder coat colours, with matching inverter covers and battery covers so your whole system looks like one tidy installation.

Not sure which size suits your inverter or battery? Use our cover finder or send us your model and we'll recommend one.