AC vs DC Coupling Explained

Written By Madeline Acri

The start of the new year is a great time to reflect on our accomplishments in 2020 and our goals for 2021. Storage grew as a prominent category over the course of the year and the momentum is here to stay. As technology evolves and new products launch, I would like to take a step back and review a foundational concept when considering solar plus storage: AC versus DC coupling. 

Let’s start by defining what AC and DC are. AC refers to alternating current, which is how our home appliances use power. DC refers to direct current, which is how solar panels and batteries create power. An inverter is a device used to convert direct current to alternating current, or vice versa. A traditional solar system uses a grid-tied inverter to input the DC from solar panels and output AC for use in your home. To add a battery to an existing solar system like the one just mentioned, an additional battery-based inverter will be installed in order to convert the DC from the battery to AC to be used by the house. This setup is defined by having 2 inverters, a grid-tie inverter and a battery-based inverter and this is called AC coupling. 

If we want to consider a DC coupled system, the DC from the solar panels and the DC from the battery can flow between each other without first being converted to AC. To accomplish this, only one battery-based inverter is necessary. However, a charge controller is necessary to enable the DC – DC relationship between the solar panels and the battery bank. Some battery-based inverters have the charge controller feature built-in and others need a separate charge controller device. 

Soligent has numerous solar plus storage offerings in both AC and DC coupled options. So, depending on if you already have solar or if you want to add batteries to a brand new system we have a solution that can meet your needs.