Stick with Solis for superior AC/DC protection
Recent years have highlighted the value of energy storage for our triumph against the ever-worsening energy crisis.
Because solar batteries store surplus energy for use when electricity from the grid is unavailable, these applications allow homes and businesses to mitigate the effects of load shedding for an uninterrupted power supply.
Solar batteries are not just a short-term solution, though. By making it possible to rely primarily on renewable, sustainable power from the sun, energy storage can make our dreams of a ‘green’ future a reality.
There are, however, a few things to consider when implementing a solar battery in a PV system. Do you opt for an AC-coupled or DC-coupled system, and what is the difference between the two?
AC and DC explained
Whilst the national grid and most household appliances use alternating current (AC), solar panels produce, and solar batteries store, direct current (DC).
A solar inverter is, therefore, needed to convert DC to AC. The inverter you need, however, depends on whether your battery is AC or DC-coupled — with ‘coupled’ referring to how solar panels connect to a battery.
AC-coupled batteries are connected to the AC grid mains from the street the system is located on.
AC-coupling is a popular option for residential battery backup and large commercial systems alike because it is easy to add additional batteries to the system down the line — resulting in less labour time for installers and, therefore, lower installation costs.
However, the current in AC-coupled systems must be inverted three times to be used for energy storage. The DC must first flow from solar panels to an inverter to be converted to AC for use in home appliances or go through another inverter to then be converted back to DC for storage.
This process can result in small efficiency losses, which is why some turn to DC-coupled systems.
DC-coupled systems are generally more efficient than AC-coupled equivalents because they only require one inverter and thus waste less energy during current conversion.
However, despite the costs saved by fewer components being needed, DC-coupling is usually the more expensive option. This is because installation for DC-coupled systems is much more complex and time-consuming, something that those installing a brand-new PV system, as opposed to a retrofit, will need to consider carefully.
The intricacies of DC-coupled systems can also complicate safety measures. Because they are more complex than AC-coupled systems, it can be challenging to protect them from common dangers — one of the most important considerations when installing PV systems.
Ensuring system safety
AC and DC disconnects are a means of protecting PV systems against damage by disconnecting the inverter from the electrical grid when it is not safe to continue running. This is needed during fires, when an inflow of power could exacerbate the spread of flames, and during storms and floods.
Installing disconnect switches with each PV system helps to prevent potential risks, but is not the only way to ensure system safety. By selecting products with safety-enhancing features, such as those from Solis’ S5 inverter range, you can have absolute peace of mind in the safety of your systems.
The recently released S5 range comprises a selection of high-quality inverters with models from 25 kW to 60 kW. These products come with type-II over-voltage surge protection for both DC and AC, the technology used to eliminate fire risk when voltage exceeds a circuit’s limit — a problem that can result from wiring errors or isolation failures.
Solis S5 inverters also come with DC reverse polarity protection, preventing system damage should a reverse electrical current occur, and DC integrated arc-fault (AFCI) protection — stopping loose or damaged wires from leading to an electrical fire.
Solis also offers the Solis Product Matrix to provide guidance to customers looking to crossmatch AC and DC protection boxes with compatible inverters.