It is an unfortunate reality that local electricity grid operators may limit the amount of solar energy you are allowed to put into the grid. Rules for solar export control are most prominent in regional grids (such as Queensland’s Ergon Energy network and Western Australia’s Horizon Power network), but they are also in place on the larger, more ‘mainstream’ grids around the country.
Why (and when) is export control necessary?
Without getting into the technical details, electricity networks have have prescribed limitations with regard to how much power they can handle without affecting power quality or resulting in a transformer blowout. Although this isn’t an issue most of the time, certain sections of the grid – especially those with a high penetration of solar PV systems – may be more prone to it. Larger solar systems slated to be sited on a commercial premises may also cause issues for the local network.
For this reason, networks may limit the size of solar systems allowed on the network, subject them to a case-by-case review, or require that an export control device be installed for them to be approved. Frequently, including an export control device in your system will earn an automatic ‘green light’ for grid connection approval, without the need for the bureaucracy to get involved for what can turn into lengthy review processes.
A map of electricity networks in the National Electricity Market. (Image via Energy One.)
Your electricity retailer vs your local network
Your electricity retailer is the company that sells you your electricity – they’re essentially a middle-man between the electricity generators and you (although they may have their own generators as well). They take on the risks associated with trading on a volatile electricity spot market and in turn deliver you predictable prices. Your retailer is the company that sends you your electricity bill.
Your local network company (or grid operator) is the company that owns/operates the physical infrastructure (‘poles and wires’) that allows for electricity to be delivered to your home. You pay for the services that the network provides indirectly through the ‘supply charges’ component of the electricity bill that your retailer sends you.
In some areas, your retailer and your network company might be one in the same. If you live in Western Australia, Tasmania, the ACT, the Northern Territory or far north Queensland, your network company may also be your retailer.
Types of solar export control
Depending on your location and the size of the solar system you have installed or intend to install, the rules may differ. That being said, there are three basic approaches to solar export control (which are summed up nicely by Horizon Power):
Solar smoothing:
The electricity generation of a solar PV system is not always smooth and consistent; passing clouds and shading from nearby objects can result in an output curve that is inconsistent or erratic. This unpredictability can be a headache for the local network (especially the smaller networks), who are constantly trying to ensure that electricity supply matches demand. A solar smoothing device (which usually includes a small battery) helps to improve the predictability and consistency of solar energy production.
A graph of a smooth solar generation curve
A graph of an inconsistent solar generation curve
Solar feed-in management:
- On the simplest level, the local network company may pre-program or remotely control your solar inverter to switch off when your solar export reaches a set threshold (e.g. 3 kilowatts – kW). With this crude approach, it may be the case that you lose all of your solar energy production for as long as your system’s output remains above the threshold.
- A second approach would be for the solar energy to be ‘clipped’ if it exceeds the threshold, so that any energy above the allowed limit is shunted into earth; this approach is less wasteful than the first, but still imperfect.
- Ideally, a more sophisticated network should be able to remotely turn on devices within your home to ‘soak up’ excess solar when available, allowing your solar system to continue to produce power. This way, the amount of solar energy wasted is as minimal as possible.
Zero solar export:
- With a zero export requirement, none of the solar power produced by your system is allowed to go into the grid at all.
- In the default approach, all solar energy produced that is in excess of demand within your home or business is shunted off, serving no useful purpose.
A smarter approach (in which a smart energy management system like carbonTRACK is deployed) would allow this excess energy to be either put to good use then and there, or sent into a battery for later.
carbonTRACK as an ideal solar export control solution
Regardless of where you are located or what the local network rules are, these days the best way to get the most out of a solar energy system is to consume the energy it produces directly, inside your home or business. Our platform has been developed to maximise savings for homes and businesses with solar – as well as those without.
