Salisbury Battery Trial charges ahead

SA Power Networks has received national accolades for its innovative Salisbury Battery Trial, which is providing important information on the impact of new behind-the-meter technologies on the energy industry.

The unique Salisbury trial – the largest of its type in Australia at the time – rolled out subsidised battery storage systems to 100 customers to create a 300kW Virtual Power Plant (VPP).

The trial recently won a national award for innovation from Energy Networks Australia. The award, announced in Canberra last year, recognises initiatives aimed at improving outcomes for customers.

The project was planned and implemented by the network strategy team at SA Power Networks, headed up by Mark Vincent, who also won an award from the ENA for his contribution to the industry, particularly recognising his leadership in planning for transformation of the sector.

“In 2016, an opportunity arose for us to explore how customer-side investment in solar PV and batteries could be an alternative to investing in a network upgrade in Salisbury in northern Adelaide, where the local network was reaching capacity at times of peak demand,” Mark told Energy Source and Distribution.

“Modelling suggested there was potentially significant whole-of-market benefits available if residential customers could gain access to the full range of value streams that batteries offer, even though individual value streams may be insufficient to encourage investment.

“We wanted to test this hypothesis in a real-world trial to see exactly what benefits could be derived for customers and other market participants, and to what extent pursuing these various benefit streams may be in conflict.

“Salisbury was selected for the trial because a $2.9 million network augmentation was planned for the area.

“The number of trial participants was selected to enable sufficient demand reduction to defer the network augmentation for three years. If the trial outcomes are favourable, the potential for further deferral also exists.”

Customers enrolling in the Salisbury trial received a battery at a discounted price in return for allowing SA Power Networks the opportunity, if needed, to access power stored in the batteries at times of peak demand.

“The project has shown that centralised control of batteries can provide network support without reducing the primary customer benefit of bill reduction through solar shifting,” Mark said.

“In the longer term, the project also has shown the potential for residential batteries to mitigate emerging system-wide challenges in maintaining network reliability, quality and security of supply as the penetration of rooftop PV continues to increase.”

Market context
South Australia has one of the highest concentrations of solar PV in the world, with about 30 per cent of the state’s 760,000 residential electricity customers having installed solar and a growing number of businesses also investing.

South Australian rooftop solar PV capacity is currently around 800MW, compared with a state peak demand of around 3000MW. Energy generated in 2015/16 was 548,000MWh, which represented 5.4 per cent of the energy delivered to SA Power Networks’ customers.

“SA Power Networks supports and recognises the growing trend to distributed generation, such as solar panels,” Mark said.

“However, it poses a significant challenge for network management and future network investment to maintain safety, reliability and quality of supply.”

A key issue is the generation profile of solar PV is not well matched to demand on the electricity distribution network.

“During the South Australian summer, solar PV makes its major energy contribution between 9am and 6pm,” Mark explained.

“The residential demand at air-conditioned premises is usually highest between 3.30pm and 9pm, but on hot summer days net peak demand on the network in residential areas occurs during the 6pm and 9pm period. So,
unfortunately, solar generation does little to support the network peak.

“However, the emergence of residential battery storage products has the potential to store and shift the usage of solar energy into the early evening, potentially flattening load profiles on the network and reducing network costs.

“Batteries also have the potential to be used in orchestrated ways to manage specific network issues and potentially defer large investments.”

To manage system integration risks arising from the leading-edge products used, SA Power Networks worked closely with key technology suppliers Reposit Power, Tesla, Samsung, SolarEdge and Billcap, with extensive lab testing prior to deployment.

Other technical risks were mitigated by a rigorous product selection process, use of two different battery vendors, and a pre-pilot trial at ten employee premises to identify potential installation, integration and telecommunications issues and develop mitigations.

Another important element of pre-work was undertaking customer focus groups to test indicative commercial offers.

“It was clear, for customers, the primary investment driver was the reduction in their electricity bill that they might achieve,” Mark said.

“However, a desire for energy independence was also a key factor, as well as having a source of back-up power.”

Customers were enrolled for the trial using a combination of direct mail-outs, web-based promotion, advertising in local papers and outbound calling. Customers with relatively high energy consumption and existing solar systems were targeted first since modelling indicated that they would receive the highest benefits. Customers registering interest were then screened to assess site suitability.

“During implementation of the trial, a site visit was made to every customer who sought to participate, to confirm the suitability of their site, considering criteria such as space, surface types and potential hazards e.g. wiring issues or asbestos,” Mark said.

“A dedicated team has continued to support customers involved in the trial.”

Early findings
Mark said a review was conducted after the first full year of operation, and in the first 12 months, the VPP had:

• Generated 531,639kWh
• Stored 140,109kWh
• Achieved $86,184 in system savings.

“The project has demonstrated with appropriate controls, batteries can provide benefits to customers, networks and other market participants, and moreover that these different benefit streams are complementary, not mutually exclusive,” Mark said.

Most customers have readily achieved forecast savings of $600+ per annum from improved self-consumption of their solar output, validating the original benefits modelling. Customers surveyed after 12 months expressed a high degree of satisfaction with the outcomes and with their energy systems.

“We’ve found customers also highly value the availability of backup power from batteries,” Mark said.

“Consequently, SA Power Networks and Reposit developed an innovative scheme whereby we can remotely signal the battery to move to a fully-charged state if there are potentially damaging storm conditions forecast, to maximise the availability of backup power in the event of a blackout. Customer feedback on this has been highly positive.”

Important network learnings
Mark said a key learning has been with customers installing solar systems of 5kW or more, even with batteries, exports are still typically significantly exceeding imports as most customers’ batteries are fully charged by midday.

Also, in very hot weather, particularly if there is a level of cloud cover, the battery systems are not significantly reducing the network peak.

“The way most battery management software is currently configured, a solar PV/battery combination doesn’t help us sufficiently in managing the peak, nor does it help reduce PV exports in the early afternoon,” Mark said.

“We had hoped that batteries might have a much more positive impact on customers’ load profiles, but with a simple ‘solar-shifting’ algorithm they do little to reduce peak demand or peak generation, which are the drivers of network costs.

“To maximise the benefits of solar PV/battery installations, smarter algorithms in battery management software are needed to slow down the rate of charging of the batteries and their rate of energy discharge so we can lop off the demand and generation peaks.

“We are already working with our control system vendor, Reposit, to develop these sorts of algorithms.

“We also need to make sure that our tariffs are designed to encourage battery vendors to configure their systems in this way, so that customers will also see a benefit.

“Without those changes to the configuration of batteries so that they charge and discharge in smarter ways, widespread uptake of batteries has the potential to lead to inefficiencies that will require a significant response from us as network managers.”

Mark said provided there are appropriate controls in place, battery storage devices can provide benefits to customers, retail and network market participants.

“Although it doesn’t make financial sense for most customers to invest in batteries just yet, prices are reducing rapidly and we think it’s inevitable that customers will invest more and more in battery systems,” he said.

“Our challenge is to make sure that they operate these systems in ways that reduce and don’t increase network costs to all customers.”

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