DC coupled battery

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

A DC coupled battery connects to the DC side of the system. Solar panels feed DC power to a hybrid inverter, and the battery charges from that DC bus directly. Energy is converted to AC only when it leaves for the house or the grid.

Fewer conversions mean fewer losses. It is why DC coupled systems commonly show a slightly better whole-system efficiency than AC coupled ones, though the gap depends on the products and operating conditions.

In practice

DC coupling is a natural fit for a new solar and battery install. One hybrid inverter manages everything, there is one app and one warranty, and the array can charge the battery even when the inverter’s AC export is limited.

Consider a 6.6 kW array with a 5 kW inverter. On a sunny midday the panels may produce more DC than the inverter can export. A DC coupled battery can absorb that extra energy that would otherwise be clipped, which is a small but real gain.

It is less convenient as a retrofit. If the customer already has a standard inverter, DC coupling normally means replacing it. That is when many installers move to AC.

For certificates, the coupling choice does not change the battery STC count. The program looks at usable capacity, the factor for the installation date and the tier percentages. See battery tier factor. The battery must still be CEC-approved and VPP-capable, and installation follows AS/NZS 5139.

Common confusion

DC coupled does not mean the battery has no inverter. The inverter is shared with the solar. Another mix-up is assuming a DC coupled system is always better. Where a customer wants to keep a recent inverter, the cost of replacing it can outweigh the efficiency gain.

See battery STCs and the Cheaper Home Batteries Program installer guide, plus the glossary.