New rules for rooftop solar installed in South Australia after 2020 to create smarter, more resilient network
Rooftop solar systems installed after 2020 in South Australia had to high-standard inverters and the ability to be disconnected and connected remotely.
Image courtesy Infinite Energy
The South Australian government’s new smarter homes rules for the installation of rooftop solar systems from 2020 involved inverters, remote disconnecting/connecting of solar systems and flexible export limits.
Under the new rules, inverters – connecting solar panels to the grid – had to be able to ride through higher levels of voltage disturbance without tripping off. An inverter, the workhorse of the solar energy system, was a box of electronics where all the solar power produced by panels passed before being transported to the home for use by in appliances – or, when surplus energy was generated, to the mains grid. Inverters couldn’t be installed unless they met new undervoltage-ride-through standards.
Also, all smart meters installed had to have at least two elements and inverters to have internet capability. All solar systems had to be capable of being disconnected and reconnected remotely and customers needed to appoint a relevant agent (e.g. SA Power Networks, Origin Energy) responsible for turning their system off and on in an emergency.
The new rules were designed to ease impacts on the South Australian power system during disturbances. The Australian Energy Market Operator reported large parts of the grid connected power inverter fleet in South Australia being disconnected during disturbances which resulted in brief low voltage excursions. This appeared to be due to some models of inverters disconnecting immediately upon measuring a grid voltage below the minimum set by Australian standards.
The new rules didn’t affect existing solar customers replacing their inverter under warranty. Some parts of South Australia’s electricity distribution network were reaching their maximum capacity to host solar exports. This was causing customer inverters to trip off or ramp down, and voltage issues for other non-solar customers nearby. In some areas, reverse solar power flows are beginning to exceed the capacity of zone substations. This had the potential to overload or damage network equipment that might lead to blackouts.
Electricity distributor SA Power Networks was working with the solar industry to develop and introduce a smart option to enable new solar customers to export up to 10kW from their solar panels. This aligned with the state government’s smarter homes rules, requiring all new solar installations to have dynamic (flexible) export limit capability.
To manage the growing amount of solar, existing South Australian solar customers currently were limited to an export limit of 5kW (kilowatts). As network congestion from solar increased, some electricity distributors in other states had introduced reduced or zero export limits in some areas, and these soon would need to be introduced in some limited parts of Adelaide’s southern suburbs.
SA Power Networks was working with the sector to develop a smart alternative – flexible exports –with a limit up to 10kW. This would be offered to new or upgrading solar customers in some congested areas, as an alternative to the option of a fixed lower export limit of 1.5kW per phase.
Less than 2% of new solar applicants in South Australia (about 800 customers) were likely to be in areas affected by this kind of network congestion. The proposal didn’t affect existing solar customers or those connecting or upgrading their systems in a part of the network that wasn’t congested. They will remain on the current limit of 5kW per phase.