Bi-Directional Inverter Assists with Load Balancing Strategies

The bi-directional inverter enables storage systems to react in real time to capacity and price signals.
Published: Wed 09 Apr 2014

The Smart Grid Research Group of Germany's Fraunhofer Institute has chosen Eguana Technologies’Bi-Direx inverter to assist distributed energy storage systems contribute to load balancing strategies, implemented by utilities and energy aggregators.

The inverter has been chosen for its flexibility and advanced high speed bi-directional controls which enable the storage systems to react in real time to capacity and pricing signals from the power grid.

According to Brent Harris, CTO of Eguana Technologies Inc., smart “edge of grid”power electronics will be a critical element of the system control strategies that will make decentralized residential and commercial storage capacity available to the power grid for load balancing in real time.

Distributed energy storage will drive distribution generation growth

In the US, distributed energy storage is expected to drive growth in distributed generation from the current 1% of total installations to as much as 33% of America's installations by 2017.

Navigant Research predicts a US$3.6 billion per year market in energy trading by 2020 in Germany, where energy aggregators are expected to gather portfolios of smaller generation and storage systems to match load fluctuations through forecasting, advance metering and computerized control.

Performing real-time optimization of energy resources, these virtual power plants represent an 'Internet of Energy,' tapping existing grid networks to tailor electricity supply and demand services for the customer.

Bi-directional inverters, like Eguana's Bi-Direx inverter, which are able to move from charge to discharge mode; and to respond in real time to capacity and pricing signals from the power grid will be critical components.

Household bi-directional inverters

Essentially, bi-directional inverters can convert DC to AC (so the array can power the house or feed into the grid) or AC to DC (so the grid can charge a bank of batteries). If a power outage occurs, the system is able to drop the grid and continue powering the house.

Not only does a bi-directional inverter and battery bank provide power, they also provide solar homeowners the flexibility of choosing when to buy power from or sell power to the grid. This allows consumers to take advantage of tiered rates.

In some places, such as Hawaii, the utility doesn’t allow customers to sell power back to the grid since too many people are doing it and the system can’t handle the influx. A battery system will allow the consumer to buy when rates are at their lowest.

The fact is that grids have a limited capacity to absorb electricity from household solar panels and wind turbines. Not only does solar and wind output fluctuate, distributed power generation can open the network to failures.

As the volume of intermittent renewable supplies escalates, the grid will become less stable. This could cause a major problem for cities that are aiming for large-scale renewable energy generation. Germany, with its ambitious clean energy strategy, Energiewende, has already experienced grid imbalances.

However, energy storage in the form of batteries can help consumers to stabilize power swings; and household invertors can help to stabilize the grid by adjusting their AC waveform.