Solid uptake of domestic solar electricity has as many supporters as it has detractors. While most would find it difficult to argue against the benefits of the more than 25 years of clean electricity that a solar unit can provide, the main opposition comes from those who feel they are not gaining any benefit from solar, and indeed, are paying to subsidise it.
The intent of government subsidies, whether it be an upfront discount (federal), or a feed-in tariff (state) seems to be lost in the negative press that surrounds these schemes. More recently, issues about domestic solar have been raised by electricity distributors, concerned that the power network is being strained by the extra feed-in of electricity.
A buzz about electricity
Electricity consumption increases by 25-30 per cent in the period between 5:00pm and 8:00pm, causing tremendous stress on the electricity network and generation plants. The design of the network and generation must be sized to suit this high demand, while taking into consideration the fact that at other times portions of this asset are essentially idle.
Finidng ways to consume and store energy to accommodate these fluctuations has been the holy grail for producers and consumers alike. Grid-demand storage units tackle this issue.
What is a grid-demand storage unit?
A grid-demand storage system is a small, high-capacity battery unit which fits next to a meter box, and is similarly sized. Coupled with an existing or new solar photovoltaic (PV) system, the unit collects and stores the energy generated by the solar panels, ready for release at the time when it is needed most – the early evening.
A grid-demand storage unit comprises a battery management unit, controls used to manage the switching in and out of the system, and a ripple control receiver which helps to monitor power supply.
The modular design of a grid-demand storage unit accepts 30 amp-hours lithium iron phosphate packs at 120 volts (v) direct current. Up to four packs at 120 v can be fitted to best match an inverter’s capacity. These are charged individually and then linked in series at the time of discharge into the inverter.
As the storage system is based at the source of the power and the load is located at the same location, and given that the power is discharged into the grid in the early evening when people are at home, the effects on electricity infrastructure, if there are any, are negligible.
Grid-demand storage systems deliver power at the full rating of the grid-connect inverter, rather than the capacity of the installed solar panels, allowing a dependable and hard-hitting boost to the electricity supply system at critical evening peaks.
Benefits of grid-demand storage
One of the benefits of grid-demand storage systems is that they can be charged from the grid during early, off-peak hours, with excess and cheap energy from the grid. This energy can then be released at the behest of the distributor to address morning demand peaks.
As a proportion of the cost of solar PV systems, a grid-demand storage unit represents a 25 per cent cost impost. This could, however, be easily compensated by a legitimate feed-in tariff, given the benefits it can provide to all electricity consumers, and its environmentally friendly nature.
Furthermore, in New South Wales, the Australian Capital Territory and Victoria, where the government has had to virtually quarantine solar feed-in tariffs to newcomers due to ill-conceived and overly generous schemes, the opportunity exists to restore the equity of the system by legislating the installation of grid-demand storage units into existing solar PV systems.
Rob Campbell has been involved in the electrical contracting industry for 27 years. Mr Campbell is currently based in Queensland and is managing director of Vulcan Energy, a contracting business that incorporates Australian Solar Systems Pty Ltd, established in 2007.
