AC-coupled vs DC-coupled Batteries
Learn the differences, features, benefits, and costs of AC-coupled compared to DC-coupled battery storage systems.
A DC-coupled system is commonly preferred when adding PV solar and battery storage for new installations. It is a more efficient and often more cost-effective approach.
Solar PV modules generate Direct Current, or DC power, which can be sent through an inverter and converted to AC power for use in the home, or stored in DC batteries when using a hybrid solar inverter.
A DC-coupled system simply means that the solar panels (producing DC power) can charge the batteries (storing DC power). The hybrid inverter can convert power from either source into AC power for use in the property. If needed, the hybrid inverter can also work in the opposite direction, converting AC utility grid power into DC power to charge the batteries.
Alternating Current (AC) or AC power is the type of electrical current provided by utility companies for use in a home or business.
An AC-coupled system is typically in two scenarios:
- Add battery backup power to a property without solar.
- Retrofit with an existing grid-tied solar array.
In an AC-coupled system, the DC solar panels are not directly wired to the DC batteries. Instead, the panels can charge the batteries by going through two conversion steps: DC-to-AC and then AC-to-DC.
First, DC power flows through a grid-tied solar inverter to be converted to AC power. Then the AC power flows through an off-grid battery inverter to be converted into DC power to charge the batteries. Each time the power is converted, there is power loss
You can add an off-grid, back-up battery to any home by simply wiring an inverter and battery to its own circuit breaker, with a transfer switch in-between. There are many inverters available today from SMA, Schneider Electric, Sol-Ark, and Outback Power that allow for AC-coupled installation.
