What is DC Coupling?

With DC coupling, your solar panels and battery usually share one hybrid inverter. Spare solar power can charge the battery without first being converted into household electricity. When you need that stored energy, the inverter converts it for your home. If you're installing solar panels and a battery together for the first time, DC coupling usually stores solar power more efficiently than AC coupling because it avoids extra conversions that lose energy.

Why there is an inverter at all

Solar panels make direct current (DC), but your home runs on alternating current (AC). An inverter converts one to the other. A battery can join your system in two ways, and the difference is where that conversion happens.

How DC coupling works

In a DC-coupled system, one hybrid inverter looks after both the panels and the battery. Solar power flows to the battery as DC, so it is converted to AC only once, when your home needs it.

With AC coupling, the battery has its own inverter and connects to your home's AC wiring beside the solar inverter. Power is converted more times, so it is a little less efficient. That is the trade-off: DC coupling wastes less, while AC coupling is easier to add to solar you already have.

Who DC coupling suits

• New solar and a battery installed together. One hybrid inverter can do both jobs, so there is only one inverter to buy and install.
• Homes planning for backup. A hybrid system can keep some circuits running in a blackout, but only if it is installed for backup. It is not automatic.

When it may not be the best fit

• You already have solar. Adding DC coupling can mean replacing your existing inverter with a hybrid. AC coupling is usually the simpler way to add a battery to existing solar.
• You have microinverters. These are small inverters under each panel. A hybrid inverter cannot be connected to them, so a battery needs its own inverter.
• You're buying a "battery-ready" hybrid for later. Advice differs. Some guides suggest a hybrid inverter if you plan a battery down the track. Others warn that one bought well before the battery may not suit the battery you eventually choose, or may be out of date by then.

How to tell what you have

Your inverter's model number is on its label, usually underneath. Look it up, or ask an installer.

What Smarter Solar does

Smarter Solar looks at how much electricity you use, any solar you already have and what you want from a battery. It gives you a free personalised plan to discuss with vetted installers. Your installer confirms which set-up suits your home.