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Nov 26 2013

Seven years of success

Si Clean Energy first introduced the Aurora range of PowerOne inverters into Australia in 2006. Since then the Aurora inverter has proven itself to be one of the most flexible, reliable and highest performing inverters in Australia. The key to understanding what has made this success possible is inside the inverter. It is the technology itself, the electronic specifications that created a device that allowed all participants in the supply chain including sales, designers and installers, and the end user to work efficiently and attain outstanding solar yields. Since 2006, many advances have been introduced into the Aurora range of inverters, but always, it is the fundamentals that are addressed by the Italian design team at PowerOne.

The three key specifications that make a great inverter are its DC input voltage range, conversion efficiency, and its Maximum Power Point Tracking (MPPT) accuracy:

The DC input voltage range determines the flexibility of the inverter. For example, the single phase Aurora string inverters will track DC voltages from 90 to 580 Volts DC. This ultra wide range combined with a dual MPPT input, makes it is possible to successfully design and install any configuration of PV array from as little as 5 x 250W panels (1.25kW) through to as many as 24 panels (6kW). The crucial point is that inverter efficiency must be maintained across the entire DC input range, and this is what the Aurora does extremely well. The same level of flexibility is also possible with Aurora three phase inverters ranging from 6kW to 27.6kW. With such a wide DC input range, the sales process at the front end of the business is made all the more easier. It means that a residential sales person does not need to calculate whether the number of panels proposed to the customer will actually work with the inverter, it is a given. For a residential sales team, it becomes a physical dimensioning exercise with the available roof top space and not an electrical design exercise.

With a base conversion efficiency ranging from 96 to 97% depending on model, the Aurora inverter has from day one maintained an extremely high performance rating. The design of the inverter and the components used including the more expensive but highly efficient Silicon Carbide power transistors has allowed for minimal conversion loss and at the same time produced an extremely low output harmonic distortion. These two contrasting specifications, efficiency and distortion require a trade-off. If you want low distortion, you include more filter capacitors and inductors, which produce more losses. If you want high efficiency, you decrease the filtering, which produces more distortion. What the Aurora specification achieves best is a balance between efficiency and distortion that delivers an exceptionally high overall yield without sacrificing harmonic distortion performance.

The accuracy of the inverter MPPT determines how much energy is produced when cloud cover interrupts the direct sun. As the clouds scud across the sky, and irradiance rapidly falls and rises, the speed of response by the inverter to the changing irradiance conditions becomes the major factor by which yield is determined. In 2006, the Aurora inverter pioneered MPPT speed and efficiency with a level that was never seen before. Since then, even better performance has been introduced that includes techniques to determine false PV array maximum power points, and to lower any AC ripple that may be induced back through the inverter onto the PV array by the MPPT system.

The combination of these three inverter specifications is what predominantly determines the annual energy yield of the PV system for a given installation. The temperature de-rating specification can also be crucial depending on the local conditions. The Aurora inverter having been designed originally for the Italian Mediterranean conditions lends itself very well to the hot and high irradiance conditions of Australia.

Si Clean Energy maintains an advanced service and repair facility at its head office in Coffs Harbour that provides high level technical support.

Seven years of success in Australia has proven that the Aurora range of PowerOne inverters available from Si Clean Energy remains one of the best choices for solar power systems.