DC-coupled battery

Written and checked by the Energy Merchants desk · Reviewed 3 October 2026

A DC-coupled battery sits on the DC side of the system. The panels and the battery share one hybrid inverter, and solar power can flow into the battery directly without first becoming AC.

What that means for efficiency

Because the solar energy is not converted to AC and back, DC coupling usually has a better round-trip efficiency for charging from the panels. The saving is real but modest, and it matters more in a system sized to charge the battery fully from the roof each day.

In practice

DC coupling is the natural choice for new installations, where the hybrid inverter, the panels and the battery are specified together. It is harder to retrofit, since an existing solar inverter may need to be replaced with a hybrid unit. That adds cost and makes the AC-coupled route attractive for existing solar. See AC-coupled.

The coupling choice does not change how STCs are calculated. The battery’s usable capacity and the factor in force on the installation date decide the number. Eligibility rules still apply: CEC-approved, VPP-capable, accredited installer, one battery per property. See battery STCs.

Worked example

A new 10 kW solar array with a 10 kWh usable DC-coupled battery is installed in 2026. The solar STCs follow the panel rating, zone and deeming period. The battery STCs follow 10 x 6.8 = 68. Both claims are made against the one installation date, but are separate calculations.

Common confusion

DC-coupled is not the same as DC-connected load. Home appliances still run on AC. It also does not mean the battery cannot charge from the grid. A hybrid inverter can charge from either, subject to the program’s and the network’s rules.

Inverter sizing is a separate subject, though related for DC-coupled designs. See inverter oversizing.

See the battery submission guide, how it works and the glossary.