For large-scale solar projects across Australia, the central challenge is shifting from how much capacity can be built to how that capacity operates once connected to the grid. Rising curtailment, persistent negative daytime pricing, and more demanding connection requirements are forcing developers to reconsider system architectures in addition to the project size. In response, attention has turned to battery-centric DC coupling as a way to improve performance, reduce losses, and better align solar generation with market value. <\/p>\n\n\n\n
Battery-centric DC-coupled systems place the battery and its inverter at the centre of the design while using DC\/DC converters, such as String Optimizers, to manage power from the PV array. These designs are being adopted by developers to improve grid interaction, increase system performance, and reduce costs. While AC-coupled and other DC-coupled designs account for the majority of operating assets in the NEM, system owners are reassessing these architectures as grid and market conditions evolve.<\/p>\n\n\n\n
To get better insight into this shift, Giles Parkinson sat down with Russell French, Country Director \u2013 Australia at Ampt; Rob Mailler, Director at Kinelli; Glenn Clark, Grid Connections Director at Power Electronics; and James Larrett, Director at Solpod and Fresh Start Energy.<\/p>\n\n\n\n
Peak solar power generation coincides with the lowest-priced periods and curtailment is becoming more common as network constraints tighten. Together, these conditions erode revenue by forcing energy into low- or negative-price windows and limit how much generation can be exported. Integrating storage allows that energy to be captured and shifted into higher-value periods, while reducing exposure to curtailment<\/p>\n\n\n\n
As a result, utility-scale solar is being designed as an integrated solar-plus-storage system rather than a standalone asset. Projects that do not incorporate storage from the outset are finding it harder to secure financing.<\/p>\n\n\n\n
With DC-coupled storage, developers can shift energy delivery into higher-value periods and make better use of limited grid connections. \u201cWe can\u2019t really effectively do large-scale solar by itself anymore,\u201d says Rob Mailler, Director at Kinelli, a solar and storage development advisory firm, \u201cAdding storage to those projects, you can solve that economic conundrum.\u201d<\/p>\n\n\n\n
Among the available approaches, battery-centric DC-coupled designs are a leading option based on their technical and economic characteristics.<\/p>\n\n\n\n
PV-plus-storage power plants with a battery-centric, DC-coupled design retain the core architecture of a standalone battery energy storage system (BESS), which has a battery connected to a bi-directional, grid-forming inverter. <\/p>\n\n\n\n
The PV system connects directly to the shared DC bus between the battery and its inverter. It does so using DC\/DC converters\u2014such as String Optimizers\u2014deployed in the PV array that deliver full available power while following the battery state of charge (SoC). This also isolates the DC bus from PV voltage variability to allow the PV-plus-storage power plant and allows the system to operate with the operational advantages of a standalone BESS rather than a solar generator.<\/p>\n\n\n\n
\u201cWhat you have from the grid\u2019s perspective is a battery facing the grid,\u201d Mailler explains. \u201cIt\u2019s supported by a battery with a very stable DC voltage. The solar comes in from the side.\u201d<\/p>\n\n\n\n
The grid connection process remains a significant source of project development costs and delays. In AC-coupled plants, the PV system and the BESS each have their own inverter and medium-voltage transformer which export power directly to the grid. With multiple grid-facing inverters there are higher harmonic emissions and a wider range of operating conditions that must be assessed through time-consuming and expensive grid studies.<\/p>\n\n\n\n
In battery-centric, DC-coupled systems only the battery inverter faces the grid and the number of interacting devices is reduced. \u201cWhen you\u2019re charging your battery, there are no harmonic emissions going onto the grid,\u201d Mailler says. \u201cWith AC-coupling, you\u2019re maximally harmonically noisy at that time.\u201d<\/p>\n\n\n\n
Glenn Clark, Grid Connections Director at Power Electronics, an inverter manufacturer, says this makes battery-centric systems easier for network operators to assess. \u201cThese designs are good citizens in the network,\u201d Clark says. \u201cThey supply very valuable services, and they reduce the complexity of the connection process.\u201d<\/p>\n\n\n\n
Four-hour batteries are common in existing deployments but only cover a short evening peak demand. As demand for longer storage durations increases, system owners are incentivised to charge batteries during periods when low grid prices and peak PV generation coincide.<\/p>\n\n\n\n
Battery-centric DC-coupled systems allow charging from both the PV and the grid, increasing the volume of energy captured within the same time period. \u201cIf you want to go long duration,\u201d Mailler says, \u201cyou\u2019ve got to go DC coupling.\u201d By contrast, AC-coupled systems are constrained by the size of the interconnection. <\/p>\n\n\n\n
Russell French, Country Director \u2013 Australia at Ampt, which manufactures DC\/DC String Optimizers, identified this capability as a priority for power plant developers. \u201cLong-duration storage is going to be the future,\u201d French says. \u201cWe need assets that are rapidly deployed, lowest cost, highest efficiency.\u201d<\/p>\n\n\n\n
The shift to hybrid designs is changing how projects are developed. \u201cYou begin with the grid connection and look at optimising what you can connect at that location,\u201d says James Larrett, Director at Solpod and Fresh Start Energy. \u201cThat\u2019s really around the battery.\u201d<\/p>\n\n\n\n
This approach allows developers to focus on increasing total energy delivered rather than maximising peak output. By prioritising energy yield over time, sites that were previously overlooked\u2014such as non-flat terrain unsuitable for trackers\u2014become viable, and denser fixed-tilt east\u2013west layouts perform more competitively when paired with storage.<\/p>\n\n\n\n
\u201cIt\u2019s not megawatt-hours per megawatt peak we\u2019re after,\u201d Larrett says. \u201cIt\u2019s megawatt-hours per hectare.\u201d<\/p>\n\n\n\n
Battery-centric hybrid designs are shaping utility-scale solar-plus-storage projects, with their advantages becoming more pronounced as congestion and curtailment increase and project economics favor longer-duration storage.<\/p>\n\n\n\n
Battery-centric designs are being used in systems ranging from five to hundreds of megawatt interconnections. Panel participants are collaborating on a 400 MW \/ 1.6 GWh battery-centric DC-coupled project in Queensland.<\/p>\n","protected":false},"excerpt":{"rendered":"
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