System solutions with Sunny Central Storage battery inverters are used in storage power plants and PV hybrid systems worldwide. They ensure the stability of transmission lines and reduce energy costs through the use of photovoltaic energy and large-scale battery-storage systems in hybrid power generation systems.
Industrial-scale energy storage solutions have become mature technology, incorporated into utility scale power plants to serve in many different applications. One major area of application is providing ancillary grid services that provide generation capacity and support grid stability.
Frequency Control ‐ P(f)
Frequency is held to a very strict tolerance, therefore, deltas in frequency must be mitigated. Renewable energy can introduce fluctuations in grid frequency. Energy storage, specifically battery storage, is an ideal way to solve this issue due to its nearly instantaneous reaction time to frequency events. Enhanced inverter controls and rapid response times make for a great combination.
Voltage Control ‐ Q(V)
Fluctuations in grid voltage, especially at the far ends of distribution feeders, can cause damage to loads and utility equipment. Battery inverters can provide full, four-quadrant support to help maintain voltage levels at points of interconnection by utilizing the volt-var function or a voltage droop.
Mismatch between load and generation will be reflected into fluctuation of the grid frequency. Storage is an economically feasible option to offer this service
If demand within a distribution network increases to the point that an asset upgrade is required, it can be extremely expensive for the grid operator. Adding energy storage, at a fraction of the cost of the upgrade, can alleviate the stress on the network caused by the demand increase.
Energy arbitrage can be a great tool for grid operators without the need of renewable generation being in the network. By charging the energy storage system either at night or during another time when energy rates are low, the grid operators have the ability to discharge later on in the day to meet demand and reduce the need for peaker plants to be utilized.
Asset Life Extension
Even if demand growth is not increasing, adding energy storage to an existing distribution network can help extend the life of the assets within the network.
Battery inverters with a DC precharge circuit and grid forming features are capable of starting a grid while down and slowly ramp up voltage to successfully startup a medium voltage transformer. This feature can be utilized by an inverter whose intended application may be for something completely different, but with minimal effort and cost.
Uninterruptable Power Supply (UPS)
Battery inverters can be utilized in several ways to replicate UPS-like functionality at a fraction of the cost of a similar-sized industrial UPS. Double-conversion, online UPS-like functionality, can be accomplished while also providing ancillary grid services to the grid operator.
AC coupling allows the energy storage systems to be placed virtually anywhere within a distribution network.
The same inverter system can be utilized for a multitude of different applications.
Energy Shifting and Clipped Loss Capture
As module prices continue to decline, increasing the DC-AC ratio on a PV inverter continues to add benefit by allowing more energy production during the shoulder hours. The downside is that there is a large amount of energy loss due to inverter clipping since they have maximum AC power limits. These limits are typically defined by the interconnection with the utility. Adding DC-coupled storage can enable the system to capture what would have otherwise been lost due to clipping and export this energy at a later time.
Solar energy is well known for being an intermittent resource due to variability in weather. When energy storage is paired on the DC side together with a solar inverter, the asset as a whole becomes much more firm and can be controlled in such a way to make it dispatchable. When the asset is dispatchable, it gets treated in the same way a peaker-power plant or generation plant would, which further strengthens renewable energy’s position in today’s energy markets.
Ramp Rate Control
In some renewable energy markets there are requirements set regarding ramp rates. Controlling ramp-up rates is relatively easy for a PV inverter. However, controlling ramp-down rates can be challenging, even with advance weather forecasting tools. Adding DC-coupled storage to a PV inverter in this scenario can overcome these challenges by using the storage as a buffer, helping to smooth out the PV inverter’s output power without increasing the nameplate rating of the plant.
Frequency Control Frequency is held to a very strict tolerance, therefore, deltas in frequency must be mitigated. Renewable energy can introduce fluctuations in grid frequency. Energy storage, specifically battery storage, is an ideal way to solve this issue due to its nearly instantaneous reaction time. Enhanced inverter controls and rapid response times make for a great combination.
Nameplate Power Rating
Add energy storage without increasing total power capacity.
Guarantee that all energy flow to and from battery is from renewables.
Increase the overall efficiency of the system.
Can be added to a PV site even after it has been commissioned and is operational.
Same inverters can be utilized for a multitude of different applications.
Most efficient to install next to the substation serving the PV site.
This DC coupled storage solution consists of SMA’s Sunny Central EV-US line of inverters with a DC coupling ready option and up to six 500kW SMA DC-DC Converters. It is ideally designed for new PV plants, but it can also be used to retrofit existing PV plants for those operators who want to enjoy the benefits of solar-plus-storage. SMA’s DC coupled solution offers significant operating cost and efficiency advantages over AC coupled systems.
The Sunny Central Storage is designed to compensate for fluctuations in solar energy generation and offers comprehensive grid management services such as automatic frequency control
The new SMA DC-DC converter allows designers to increase their PV power plant’s yields by oversizing the DC array without compromising energy losses. This is accomplished with the new DC-coupling option and the generous DC–AC ratios of the Sunny Central EV inverter series.
SMA PV diesel solutions offer independence from fossil fuels and reduce operating and maintenance costs, especially in remote areas far from the utility grid. Diesel fuel costs are reduced and all environmental regulations, including those regarding CO2, can be met reliably.