This complex multi-rooftop system picked up a Solar Design and Installation Award
for its innovative design and many elegant technical solutions.

In October last year, at the 2015 Clean Energy Council Solar Design and Installation Awards, one of the award-winning installations stood out from the others with its eye-catching panel layout. It was a 355 kW rooftop system at the Burder Industries manufacturing facility in Wangaratta, Victoria, which picked up the gong for best grid-connect PV system over 100 kW. At the time, the standout feature of the installation seemed to be that some of the roof panels had been used to spell the name ‘BURDER’ across the roof of the facility, which, while undoubtedly a great marketing feature, seemed a somewhat flimsy basis for an industry accolade. Needless to say, however, there was more to the project than this. In fact, that was perhaps the least important of the standout features on this project, as EcoGeneration recently discovered.

We caught up with technical supervisor Matt Wilson. Matt is part of the tight-knit crew at Melbourne-based solar company EnviroGroup, and here he tells us how he and his team overcame numerous technical and practical challenges on the way to completing the project in a lightning-fast 26 days.

Tell us about this project – who was the client and why did they have the solar system installed?

Burder Industries manufactures agricultural equipment — things like front-end loaders, forklifts and hay-handling machinery for use with tractors and loaders. The company competes directly with imported equipment produced at a lower cost overseas, so it needed to reduce its costs to increase competitiveness and protect local jobs. As a large user of electricity, Burder saw solar power as an effective way of reducing its operating costs. It was a big capital investment for the company, but they saw it as essential for their long-term competitiveness.

Were there any grants or funding available for the project?

Yes. With help from EnviroGroup, Burder negotiated a grant through the AusIndustry Clean Technology Innovation Fund. This grant was available to Australian manufacturers attempting to maintain competitiveness in a ‘carbon constrained’ economy, and covered 50 per cent of the cost of the installation. A provision of the AusIndustry agreement was that installation had to be completed and all paperwork submitted by 30 June 2014, which put us on a very tight deadline. We had to proceed quickly in nforeseen pre-approvals and liaise closely with the electricity distributer, AusNet Services, throughout the project to meet all of their requirements. Excellent planning and communication ensured that the system was installed within two months, leaving a month to spare for nforeseen n of grant paperwork.

How exactly did the client’s power needs lend themselves to a solar PV solution?

The client operates during daylight hours, six days a week, with a fairly flat load curve during operating hours. A major rewire of the premises was also required. It was a good opportunity to install PV generation and take advantage of the subsequent grant opportunity all in one project.

How did you determine the size of the installed system? What percentage of the client’s power needs does this represent?

Our aim was to meet 90 per cent of the site’s load requirements, and this meant installing panels on every available surface. We used all available roofs, including three separate buildings. The roof orientations included north, north-east, north-west and south-west facing. There were tilted and flat roofs, as well as a number of skylights and vents, so we had to be very careful to design around these while still nforeseen yield and meeting the requested capacity rating. We also incorporated a north-facing solar façade on the side of one of the buildings, due to limited north-facing roof space.

What were some of the challenges of this multi-rooftop layout?

There were significant space issues that made installation very technical. Every nforeseen of space was at a premium, making inter-array shading and shading from the various building ridge caps and plant equipment a serious concern. EnviroGroup’s design team used solar shading analysis tools (Pathfinder) to ensure that winter sun angles did not result in system shading. We also installed 20 SMA 17 kW Tripower inverters with duel MPPTs, providing a high level of fault tolerance and flexibility. Where shading was unavoidable, the design team nforese the multiple MPPTs available to reduce the impact of the shading without causing major output losses. Due to the high number of different panel angles and orientations for each MPPT, the resulting overall generation curve is flattened to better match the site load profile.

What other technical challenges did you encounter?

There were several major issues we had to overcome:
1. The client site comprised two land titles with three power connections.
2. All three power connections were linked to the one overloaded transformer shared with neighbours.
3. There was significant distance of some loads to the one overloaded transformer, with undersized existing cables, causing volt drop issues.
4. There was a large plasma cutter on site causing flicker issues.
5. All three power connections had poor power factor.

To overcome these problems, we had to install a bit of extra infrastructure and come up with a few innovative solutions. To get around the land title issue, we designed the installation as two systems, with 29.75 kW of PV on the first property and 325 kW of PV on the second property. In order to stop overloading of the existing transformer, we project-managed the installation of a new dedicated 500 kVA transformer and supply at a location closer to the plasma cutter, and provided in-house engineering support for removal of the second and third supply, rewiring of the factory and design of a new main switchboard. To eliminate the poor power factor, we installed 200 kVAr of power factor correction, and to eliminate the flicker from the plasma cutter we installed a 400 A series reactor. On top of these issues, the placement of the SMA inverters proved to be quite difficult, as there was nowhere identified within the facility where they could fit. The facility also gets very dusty, and the SMA 17000TL inverters have an in-built fan which can get clogged if they are subjected to too much dust. In order to manage this, we came up with the solution of installing a mezzanine especially for the inverters in one of the three buildings where inverters were installed. To keep the costs down, the mezzanine was designed, built and installed by Burder using their expertise as a metal shop. In the second building, an existing lean-to was modified for the inverters, also by Burder.

Did splitting the system over two land titles create any other nforeseen complications?

A couple, yes. With two adjacent land titles, we effectively had two separate solar installations. However, the system monitoring had to be unified in a single web-based system. To overcome this, we placed a single SMA Bluetooth repeater to connect the two communications systems. As such, only one ‘SMA web box’ datalogger and web communications system was required. The location of the single repeater provides excellent communications reliability, despite having inverters in three separate buildings spread far apart. We also had issues with certificates because we ended up with a small-scale system (29.75 kW) generating STCs on the first land title, and a large-scale system (325 kW) generating LGCs on the second land title. As such, we had to carefully negotiate both the accreditation as a power station and the application for generation of LGCs. EnviroGroup designed and installed the solar power logging required for creation of LGCs and trained the client on how to use the system before handover.

What do you think made this project stand out to the Solar Design and Installation Awards judges?

I think spelling the company name across the roof using solar PV panels was a factor. But also the construction of the second-storey mezzanine for inverter placement, the new 500 kVA substation, the 200 kVAr Power Factor Correction to correct power quality and increase energy efficiency, and the innovative solutions required to fit 355 kW of solar PV panels in a constrained roof space. Also the fact that we completed the installation in 26 days, enabling all government grants and rebates to be claimed by the client.