Lots of customers are adding solar batteries to their solar PV systems, thanks to their impressive list of benefits. After all, having a solar battery allows you to access the power at night, saving more money on your electricity bills, even when the sun isn’t out.
Introducing AC and DC coupling
In order to make the most of solar batteries, you need to understand that there are two possible systems – known as AC and DC coupling. It essentially refers to the way that your solar panels link to a battery or energy storage system. DC stands for direct current, while ac refers to alternating current.
The main difference between the two is in the journey that each outlet takes once the electricity has been generated by your solar panels. If solar generates DC power, it must then transform into AC electricity to power the majority of your home’s appliances. But it’s common for most solar batteries to store energy in DC form.
In the past, AC battery storage systems were used primarily for residential and commercial purposes, but as DC has become more widely available, DC coupling is also increasingly becoming the most popular option. There are pros and cons to AC and DC coupling, and the way that your solar panels generate electricity will determine which approach is best for you.
AC Coupling
If you have an AC-coupled system, it means that DC electricity flows to your home via an inverter. The role of the inverter is to transform the electricity into AC electricity that can power your home. If the electricity isn’t required to power your home, another inverter converts it back into DC to enable its storage in batteries until it is required.
AC batteries are a relatively new product in the world of grid-connected home energy storage, and most AC batteries have a lithium battery module, a management system, and an inverter and charger all in one. This makes them ideal for home installation and is the main reason that they’re popular with homeowners.
Pros of AC
- AC coupled batteries are easy to retrofit.
- Battery faults won’t directly influence your solar PV generation, making them reliable.
- AC systems are flexible as they’re not restricted to where you put your batteries or inverters.
Cons of AC
- Because AC requires separate inverters for your battery and panels, it can be expensive.
- Some AC batteries aren’t capable of providing a backup supply of energy.
DC Coupling
In contrast to an AC system, a DC system directly connects to your solar panels before the generation meter. As such, direct current runs directly from your solar panels to a charge controller that then feeds into your battery system. In essence, the current only needs to be inverted once from DC to AC.
Pros of DC
- Because the panels and batteries share an inverter, a DC system is cheaper than its AC counterpart.
- A DC-coupled battery system makes it easier to oversize, meaning you can harvest more solar power from your roof.
Cons of DC
- DC systems cannot charge from the grid.
- When installing a DC system, there’s less flexibility as the batteries need to be next to the inverter for the system to work.
The verdict
The reality is that both AC and DC systems can be used for powering your home. But the bottom line is that installing a battery storage system can increase your home’s use of renewable energy, making it a great addition to your solar system this year.
