Home Batteries: AC-Coupled vs. DC-Coupled

With the introduction of feed-in tariffs, it has become even more important to use the energy you generate yourself directly—since you now have to pay for energy fed back into the grid. To increase your self-consumption, you can use either an AC-coupled or DC-coupled home battery. Here, we explain the difference!

From Solar Panels to Inverter

Let’s start at the beginning. Solar panels generate direct current (DC), while the electricity used in your home is alternating current (AC). This means the DC must be converted, which is done by an inverter.

There are central inverters, typically mounted inside the home, and micro-inverters, which are much smaller and installed underneath each individual panel.

From Inverter to Fuse Box

A central inverter is connected to the solar panels via DC cabling. The inverter converts the DC to AC, and the AC then flows through a power cable to the main fuse box (meter cupboard). From there, it’s either used in the home or fed back into the grid.

Micro-inverters, on the other hand, convert the current to AC directly on the roof. The AC then flows straight from the solar panels to the fuse box, where it’s distributed or sent to the grid.

The AC-Coupled Home Battery

A home battery stores energy in DC form. In an AC-coupled system, the current is converted three times:

1. From DC (solar panels) to AC (inverter),

2. From AC to DC (into the battery),

3. From DC back to AC (to power your home).

Brands like Enphase, APsystems, AlphaESS and Sessy offer AC-coupled batteries.

The DC-Coupled Home Battery

In a DC-coupled setup, the current is converted only once—when it leaves the battery to power your home. The DC flows from the panels to either the battery or the hybrid inverter. This setup requires a hybrid inverter. Brands such as SolarEdge, BYD, and Dyness offer DC-coupled solutions.

Advantages of AC-Coupled Home Batteries

• Compatible with any existing PV system
• Wide choice of brands, capacities, and cell types
• Easy to export surplus energy to the grid
• Separate power output from solar and battery inverters
• Ideal for retrofitting to existing systems

Advantages of DC-Coupled Home Batteries

• No separate battery inverter needed
• Single connection in the fuse box
• Only one conversion (DC to AC), reducing losses
• More compact setup
• Often lower total purchase price compared to AC + separate inverter

Disadvantages of AC-Coupled Home Batteries

• Three-stage conversion increases energy loss
• Requires an additional fuse box connection
• Requires a dedicated battery inverter

Disadvantages of DC-Coupled Home Batteries

• Limited compatibility based on inverter brand
• Hybrid inverters are more expensive than standard ones
• PV inverter limits how much power the battery can supply

As you can see, both systems have their pros and cons. A home battery helps increase your self-consumption and reduce feed-in charges. The right solution for you depends on your energy needs and setup.

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