​Solar now loses almost two-thirds of the NEM’s average price due to saturation at the time of day it dispatches. A battery shifts that generation into higher-priced hours. There are three ways to connect solar and storage: AC-coupling, DC-coupling, and reverse DC-coupling.

The choice of coupling shifts NEM energy revenue by less than 2%, so the revenue forecast alone is not prescriptive. This guide compares them across three themes: design and performance; registration and dispatch; and cost, revenue and risk. A summary of the considerations can be found in this comparison table.

Executive summary

• Solar and battery couple in three ways: AC, standard DC, and reverse DC. In the NEM, the choice shifts energy revenue by less than 2%.
• DC coupling's edge is real, but limited: 1-2% lower round-trip losses and a slight capital saving. Recovered clipped solar is worth under 1% of revenue.
• Combining assets increases risk. AC can keep the solar and battery separate across timelines, financing, contracts, and inverters. DC ties them together behind one inverter.
• The technology track record is still building. AC is proven for retrofits, and the first AC greenfield is now online. DC and reverse DC are moving to the first deployments in 2027.

The three coupling types defining hybrid systems

1. AC coupling: the solar array and the battery each have their own inverter and LV/MV transformers. The two meet on the AC side, at a shared connection point.
2. Standard DC coupling: solar and battery share one inverter. The battery connects to the DC bus via a DC-DC converter, charging directly from the array's DC output. The solar sits in front of the converter and uses a solar inverter, so it is grid-following. Grid-forming hybrid inverters are emerging, but have not yet met AEMO standards.
3. Reverse DC coupling: solar and battery share a single inverter, but the solar connects to the DC bus via the converter. The battery still charges directly from the solar, but sits in front of the converter and uses a battery inverter, so it is grid-forming.

Standard DC was the first DC architecture. It adds storage on the DC side, while retaining the more mature solar inverters. It is also more efficient for solar's direct export, which suits an undersized battery with less storage capacity. Fulham and Blind Creek, both due in 2027, are standard DC. In each, the battery is two hours and undersized relative to the solar.

The average storage duration has since increased, and reverse DC technology has advanced, with proven grid-forming capabilities. So, reverse DC is now the standard for DC architecture. Smoky Creek and Guthrie's Gap, also targeting 2027, are the NEM's first reverse DC assets.