What is an AC-coupled energy storage system?
An AC-coupled storage system is connected to your switchboard.
The main advantage of AC-coupled battery storage is that it is the easiest and generally more cost-effective way to retrofit batteries onto a pre-existing solar PV system.
Examples of AC-coupled solutions include the Varta Pulse 6, Sonnen & of course Tesla Powerwall 2.
View AC Coupled options here
What is a DC-coupled energy storage system?
A DC-connected energy storage system connects to the grid mains at the same place as the solar panels; this usually means that they share a ‘Hybrid Inverter’. You can think of this as a ‘one box’ solution, because there is only one inverter instead of two.
Because they contain fewer components (which usually translates into lower costs), we generally recommend DC-coupled systems for homes considering a brand new solar & storage system (as opposed to a retrofit).
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This is probably the most relevant question to ask. Does the proposed battery solution work when the grid is down. For some people it’s not that important, for others it is crucial.
As a general rule DC coupled options have the better backup capability. We prefer Sungrow SH5k-20 or Solar Edge (Both DC Coupled options) if backup is preferred , Varta Pulse does not offer backup power why the Sonnen battery has the ability to backup one circuit.
Which one is right for you?
Whether an AC-coupled or DC-coupled battery solution is right for your home depends on a number of factors, including whether you have a pre-existing solar system or are starting from scratch with a brand new system.