The future of ripple control and peak demand management in New Zealand
December 16, 2020

Peter Brown

All 29 of NZ electricity distribution businesses (EDBs) use ripple control to help manage electricity demand. To inform future planning around management of peak demand, the Energy Efficiency and Conservation Authority (EECA) wanted to better understand the current use of ripple control and EDB’s future plans around demand management. They engaged PSC to prepare a report looking at these factors and also barriers to effective use of ripple control.


Ripple control is one of New Zealand’s primary tools for managing electricity demand during peak times. As it plans for the future, EECA needed to understand the current usage of this technology, any barriers to its efficient use, and what alternatives will become available in the medium term. PSC engaged with EDBs and key stakeholders and conducted desktop research and consumer surveys to prepare a report to help EECA plan for the future of demand management in New Zealand. In this post we outline some of our notable findings.

Current use

All of New Zealand’s EDBs use ripple control, though ownership varies. Depending on the area, ownership of ripple relays is split between EDBs, electricity retailers and metering equipment providers (MEPs). The report concluded that most ripple control plant is in good condition and $16m in capital expenditure is expected up to 2029.

It was interesting to see that while its primary use was to reduce peak loads, a high proportion of EDBs surveyed noted other motivations and uses. These included:

  • 80% used ripple control to manage emergency load shedding
  • 70% used it to alleviate distribution network constraints
  • 70% indicated it helped to defer capital investment

Another interesting finding was around the use of ripple control to earn revenue:Some EDBs use ripple relays to drop load in response to low-frequency events by having low frequency load shedding as a function programmed into ripple relays. This enables them to earn revenue in the reserve market for fast, interruptible load. Low frequency activation typically only occurs a few times per year, and EDBs usually participate only outside the winter months, as ‘ripple reserve’ cannot be offered during periods when ripple control is already in use.”

It was also noted that adverse interactions, which have been anecdotally thought to be an issue, were in fact not widespread. 98% of consumers surveyed did not feel that ripple control interfered with their other electrical appliances or cause lighting to flicker or buzz.


The survey of EDBs found that ripple control is not being used to its full capability. The main barrier is the lack of a national, industry-wide strategy around load control. There is also a lack of financial incentives for both EDBs and consumers. The report found that fear of reputational damage and public expectations that EDBs provide a stable and secure electricity supply was actually the greatest motivator in maintaining ripple control plant. Further, the report states, “EDBs also point out there is a disincentive to providing ripple control because by allowing peak loads to rise, EDBs could upgrade their network and increase their revenues.”

Future use and alternatives

While in the next few years most EDBs see ripple control as a cost-effective method of managing domestic hot water load, in the longer term it appears that ripple control is on the way out. Technologies set to displace it include advanced smart meters and home automation, appliances that can adjust load according to price signals, consumer-level energy trading software and cellular and broadband communication.

The report finds that “These technologies will combine to monitor, forecast, control and coordinate energy generation, demand and storage. They will surpass ripple control in their ability to control consumer equipment according to market conditions and provide real-time data on consumption at the household level. Some retailers and EDBs in New Zealand are carrying out small trials of these technologies, however, their introduction is slow and piecemeal.”

 The full report can be accessed from EECA’s website here.

For more information, get in touch with the report authors, PSC’s  Ross Gaspard and Keith Fisk, or Michael Lord, independent climate change researcher.