DC-coupled battery drives efficiencies
Hybrid inverters are proving their worth in residential PV systems, writes Fimer Australia technical sales lead Warren Merritt.
As more families look to get energy storage systems installed and home battery incentives from state governments continue, homeowners and installers need to look at new technology that will offer the best solution rather than doing what has been done before. In the past, there were many hybrid inverters and DC-coupled solutions manufactured independent of one another and although in theory this technology offered the best solution, it sometimes failed if technologies didn’t speak to each other. When a problem came up, finger-pointing ensued.
The workaround for installers and homeowners was and still is for households to select a separate solar “battery-ready” inverter and an AC-coupled battery, generally from different manufacturers. Although effective, the solution does not provide an optimal option. It also means in states where there is a 10kW restriction on each phase you aren’t able to generate enough solar to charge your battery, especially when a household already has a large solar system installed.
Selecting a combined hybrid inverter and DC-coupled battery solution presents a range of benefits over the traditional AC-couple battery approach. With an AC-coupled battery installation, energy is converted from DC to AC and back again several times before being used in the house. Having to convert the energy across the inverter and the battery up to three times equates to energy loss.
Looking at one of the latest combined solutions, the Fimer React 2 hybrid inverter and energy storage solution provides up to 10% more efficiency than other systems as the power from the solar PV is used to directly charge the batteries DC/DC and the inverter only converts the battery energy to AC when needed by the house.
Another way households can generate and store more energy with a combined hybrid inverter and energy storage system with an AC and DC side connection is to bypass the 10kW restriction and add more generation to the DC side that charges the battery so the AC side can generate and export to the grid.
One of the common pitfuls when looking at a DC-coupled energy storage solution and hybrid inverter manufactured by different companies is trying to get the two to communicate as well as integrating a power meter and troubleshooting. This can also be said for an AC-coupled battery and solar “battery-ready” inverter.
A combined solution from one manufacturer eliminates these risks as monitoring is made much more straightforward to eliminate the risk of errors and problems at installation time and down the track.
A combined system from one manufacturer allows a solar and battery solution to be installed and commissioned much quicker than installing a separate inverter and battery product as there are two different set-ups involved. Fimer’s React 2 has been built to be installed and commissioned easily and quickly with a simple plug and play cable on both the inverter and battery sides.
Technology is continually evolving, so buying a battery-ready solar inverter today may mean it isn’t compatible when you go to install a battery. By choosing a hybrid inverter that is part of a combined energy storage solution from a single manufacturer, you know you can connect the battery system when ready. For example, with the Fimer React 2, the system allows you to install the hybrid inverter by itself and when you are ready have the choice to install up to three 4kWh battery modules for 12kwh of energy storage, offering a lot more flexibility to the homeowner.