Resource88 Solar PV System

A property management firm approached Blue Green Engineering in early 2010 to install solar PV onto one of their office buildings. The client had a strong emphasis on sustainability.

Originally our client was offered a 10kW peak PV system on their roof by one of our competitors. It was found that this was the maximum size the roof could fit in terms of solar panels. This offer was under serious consideration from our client. However, Blue Green Engineering took a more thorough inspection of the roof and the surrounding shading elements and found that a significant area of the roof was shaded during the cooler seasons. As a result, Blue Green Engineering proposed a 5.4kW PV system that would be 45% less costly and that would have the same annual energy output as our competitor’s 10kW system.

Problem diagnosis and solution

The design of the PV system for this particular client was not a simple matter, as the system was expected to achieve maximum energy production from most of the unshaded section of the roof. Blue Green Engineering took a number of steps to ensure that this goal is accomplished.

First, we surveyed the site using a solar pathfinder to understand how much shading was occurring on the roof at different times of the year. Based on this data, we were then able to choose areas of the roof that received the least shading in order to mount solar panels. High efficiency panels were chosen for the system, as there was a limited available area. We used solar panels with a module efficiency of 15.7%. Higher efficiency modules were also available, but they would have cost significantly more. In order to maximise the energy output of the panels we selected, we also chose to tilt them. This further helped the performance of the panels, as the roof was almost flat, sloping south. The solar panels were tilted enough so that they would be self cleaning in the rain. All mounting used adhered to Australian wind loading standards.

Secondly, we came up with a novel design of two separate inverters for the 5.4kW system. One inverter was connected to the panels that were not shaded throughout the year. The other inverter was connected to panels that were partially shaded in some of the cooler months of the year. The latter inverter had two maximum power point trackers that reduced losses accrued by the partially shaded panels.

Outcomes

Blue Green Engineering designed, supplied and installed a turnkey solar PV solution with high performance ratio for the property group. The system adheres to all relevant Australian standards and is now generating electricity which is fed into the grid. Furthermore, this solar PV system has added the benefit of green power to the already sustainable building design, and has increased the value of the premises.

Resource88 solar PV system