Alison Lennon1

1, UNSW Sydney, Sydney, New South Wales, Australia

Photovoltaic (PV) systems are increasingly being used to harvest solar energy for increased sustainability. Because solar energy is ubiquitous, electricity can be generated closer to where it is required, thereby reducing transmission costs and losses and diminishing our reliance on traditional fossil fuels. Photovoltaic generators can come in the form of large-scale solar farms or small-scale systems integrated within the built environment. Either way it is more economical to use power closer to where it is generated. For example, many freeways have large noise minimising facades on the sides of the freeway. These, surfaces like residential roofs, can be used to harvest solar energy for the purposes of lighting, tunnel ventilation and electric vehicle charging.

However PV generators can exhibit high-frequency variations in their power output due to the intermittence of illumination. These variations can reduce the power quality and reliability in mini or micro-grids due to the reduced synchronous inertia. Energy storage can be used to address these issues by decoupling generation from demand. In addition to enabling load shifting, stored energy can be used to reduce the ramp rate of generated power and also improve power quality by reacting to detected frequency variations when the PV inverter connects to the grid. However, these latter fast frequency responses require that the energy storage system can be charged and discharged quickly and is capable of many cycles to be cost effective.

This paper will discuss the potential of integrating electrochemical capacitors capable of fast charging and discharging with the electronics of PV inverters or module-level power maximisers. With the increased availability of internet connectivity, the power buffering provided by these fast responding storage systems can be tuned according to expected shading events and/or external control systems for increased efficiency and power quality. Reliable local power can make possible a range of distributed power applications and allow higher PV penetration levels.