Solar & the power of the sun
Deconstructing Industrial is a series that breaks down Industrial sites into their core components and asks - how should we look after them?
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Edward Creedy from Mainfreight

With great roofs come great opportunities.

And Mainfreight is putting these to good use with solar farms.

We sat down with Mainfreight New Zealand's Head of Property, Edward Creedy to discuss their approach and learnings.


Need to know info about Solar panels

  1. Solar panels require their own maintenance schedule and the set up can lead to massive savings over time. Mainfreight uses glass-on-glass instead of foil backed panels due to NZ weather conditions.
  2. They can be mounted on purlins (roof frame) using mounting systems and/or screws. You just need to make sure these are and continue to be weathertight over time.
  3. Uptime and energy production depend on their mounting angle, the connection in their strings and avoiding natural sources of shade.


SPEAKERS: Edward Creedy, Georgie Fenwicke

Georgie Fenwicke 

Industrial zones are the powerhouse of cities.  

This series, Deconstructing Industrial, is brought to you by Frankie - Industrious Property Software. Over the next few weeks, you'll hear from some of the best in the business as we break down industrial sites to the core components. 

I'm Georgie Fenwicke, your host. Today's topic - solar panels. 

We're joined by Edward Creedy, National Head of Property for Mainfreight New Zealand, to discuss the solar arrays they've been working on for the last six years. 

But before we jump into our conversation with him a few things to know about commercial solar farms. 

1. Roofs are great locations for them because of the direct sunlight and regular rainfall. 

2. They need to be maintained well to protect the building itself. Regular washes correctly installing the systems and using walkways like monkey toe to enable easy access for checks and regular maintenance are all required to make to make the project a success. 

3. Significant energy and cost savings are enabled as well. We talked to Ed about the house The Auckland size becomes almost completely self sufficient over Summer. 

4. The market is also heating up. Recent large scale solar projects by Vector Powersmart at Sylvia Park Mall, Yealands and Watercare generate more than 1.7 megawatts. And to date, Goodman Property Group has installed over 45 megawatts of solar PV on properties globally, with a 2025 target of 100 megawatts. 

And now to the conversation with Ed. Mainfreight has over 20 sites across the country and were one of the first to test large scale solar roofing arrays.

We start with how Mainfreight got into this in the first place.

Edward Creedy  01:40

It started with our Chairman and founder, Bruce Plested. He has always had a connection and desire to ensure that Mainfreight, no matter where we are, give back to the environment.

Georgie Fenwicke  01:52

Can you take us through an example of one of your solar farms?

Edward Creedy  01:56

So this one - our Westney Road site, that's the one you drive past on the way to the Airport with all the flags on there - this has 422 kilowatt system that was put up there. So I think it's off the top of my head, I think it's about 1800 individual panels. 

These are glass on glass panels monocrystalline. And what we're seeing from that installation is quite high generation higher than what we anticipated when we did the feasibility review of that.

On average, the site's probably using about 360 kilowatts and the peak in summer. And that's because of the freezers and chillers that we have on site and some of the logistics.   So the site's catering in those peaks when we're generating full site, so we can be offgrid for big periods of the day. Unfortunately, battery technology isn't quite there.

So we're unable to store it effectively, you know, lithium, the cost of lithium and the the issue around lithium and it only being usable for 10 years is an issue for us and the mining of copper cobalt as an issu that we see. So until new technology comes to the forefront, we're not going to battery storage just yet. 

Georgie Fenwicke  03:06

Can you export power back to the grid?

Edward Creedy  03:09

We export, we're limited by the lines company. So we can at 85 kilowatts when we are exporting back to the local substation.

At our Tauranga transport hub, we've just put up 100 kw system on that roof that was just installed finished three weeks ago. And new sites that we're constantly developing and constructing, we would look at a solar PV arrays, always in conjunction with the design.

Georgie Fenwicke  03:35

What are the important factors to take into account when you're considering a project like this?

Edward Creedy  03:42

When you look at something like this around feasibility, obviously there has to be sun.  Temperature is an issue, whether you mount them it off the roof - a lot of people just mount them flat. There's a whole heap of factors that go into making sure that that's going to be achievable for our site. And that throws up another whole maintenance issue around it  as well.

Georgie Fenwicke  04:00

Exactly which is why I was super fascinated. I talked to Paul about this last week because as soon as you get sort of weight on roofs, particularly so with coated steel, you've got to have the frame underneath to  support it and then you've also got to be able to go on both clean the roof and clean the keep the panels as well.

Edward Creedy  04:21

So that is a driver why we use glass on glass. We don't use framed panels, okay, because your rain washing basically the first part of the panel to fail and when you look at feasibility, they will say to you this will last for 20 years.

Well, aluminium on a panel out in the sun in NZ weather will not last 20 years. That's just the reality.  So the first part of the frame to fail will be your aluminium frame if you use that. You'll get water egress, you'll dirt collection on the panels because it has a frame etc. So we go glass on glass for that reason.

The trade off what that it's heavier so our structural design of the whole legs and it's mainly the purlins. So purlins are - don't know how much technical knowledge you all have - purlins are  the galved connectors between the portal frames that the roof is screwed on for structure. 

Georgie Fenwicke  05:09

Well, you can clip them on, as Paul was telling me about last week, but most screwed. 

Edward Creedy  05:13

Yeah, wasn't sure. He was probably talking about the channel as well. So with those purlins, you either have to increase the number of them to cater for the weight and spread of it. And that's all trade offs and design factors that we deal with.

So those are some of our drivers on why we've gone this way. The other factors is we use monocrystalline panels, so it's a higher silicon content that are more efficient, so they generate DC power out of the sunlight.

Georgie Fenwicke  05:44

It's been awesome  chatting to Edward from Mainfreight, we discussed a few other key things to consider about solar installations: 

1. Mounting systems - aluminium frames can wear out faster than using glass on glass. 
2. Screws cause leaks - the fewer you can use, the better to look after your roof. 
3. Mounting angles - 10 degrees is optimal in Auckland, but it depends on where you are in the world and the angle to the sun. 
4. Panel strings are like fairy lights. If one goes, they all go, but specialist systems can notify you if this happens. But there's a cost element to consider in these 
5. Shading from buildings or trees has a negative impact on generation. But Tigo Energy optimizers can be fitted to panels to turn them on and off when shading is an issue. 

We'd like to thank Edward Creedy from Mainfreight for his time. 

This series is Deconstructing Industrial - a series that breaks down building components so that we know what to do to look after them. 

Thanks for listening. And don't forget to click subscribe for more updates.

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