Large PV systems are installed on premises that normally have high levels of self-consumption, such as factories or dairy farms. During daytime hours and weekdays most or all of the electricity being produced will be consumed directly on site with very little being exported. Only on days such as weekends and bank holidays is there potential for all the power generated to end up exported onto the grid. To avoid issues with the grid, Distribution Network Operators (DNOs) require that no more than a pre-determined amount of electricity can ever be exported onto the grid. With export limitation, the DNO doesn’t have to worry about large amounts of surplus electricity entering the grid on weekends and bank holidays (when it is least needed).
A major expense when installing commercial PV systems over 16A per phase can be the cost to upgrade the grid infrastructure to accommodate the increased power flowing from the array to the grid. The cables and transformers need to be able to deal with the maximum energy the PV system is going to export. Unfortunately, because of this some commercial PV systems are considered non-viable due to the high costs. With export limitation the installation owner can reduce their electricity bill with a PV installation without the extra cost of upgrading the grid infrastructure.
The PV installation will never export more than the allowed power onto the grid. So you do not need to include costs for upgrading the grid infrastructure and the DNO will not have to worry about an extra burden on the grid.
Your customer can install the full capacity of PV that the location can support, without exceeding the DNO limitation. Produce all the PV power needed, exactly when it’s needed. During evenings, weekends and bank holidays the system will automatically limit the export power. And unlike most similar systems, the SMA export limitation system does not shut down the inverters completely, but only reduces their output power.
The SMA export limitation system is incredibly clever, yet also very easy to implement. Adding the system to an installation is basically plug-and-play. Once set-up, the Cluster Controller or the Sunny Home Manager will control the export power based on data received from the SMA Energy Meter and the inverter(s). There’s no extra work for the end user.
The SMA export limitation system has been extensively tested and has proved that it meets all DNO requirements for the grid. Thanks to a fail-safe system, hard wire communication and other safety features, your customer can count on a reliable operation.
The SMA export limitation system is a sophisticated yet simple to implement way of managing the amount of exported power. The system requires the SMA Cluster Controller or the Sunny Home Manager, the SMA Energy Meter and compatible SMA inverters with Speedwire/Webconnect interface.
The Active Power Feed-In Value is configured in the Cluster Controller and the Sunny Home Manager. This is the maximum amount of power the system is allowed to export onto the grid. If the balance between PV generation and self-consumption reaches a point where the system might export more than this value, then the Cluster Controller or Sunny Home Manager can tell the inverters to limit their production. It does not completely shut down the inverters, as most other systems do. With this solution the amount of generated PV power is maximized, matching exactly the local power demand plus the maximum possible export power.
The SMA Energy Meter is a bidirectional meter that takes measurements of the grid at the point of connection. It communicates the power consumption and export values to the Cluster Controller or the Sunny Home Manager via Speedwire (Ethernet cable) every second. This meter can be used for single-phase or three-phase systems and its maximum current is 63A.
Generated PV power with SMA export limitation = local power demand + export power
|Cluster Controller||Sunny Home Manager|
|Installation size:||Max. 75 inverters||Max. 12 inverters|
|Set up:||In Cluster Controller interface||In Sunny Portal|
|Settling time:||3 – 10 seconds||5 – 10 seconds|
|Reaction time Zero Export:||2.85 seconds||2.54 seconds|
|Connection to network router:||Ethernet cable||Ethernet cable|
|Active power export limitation:||100% of inverter nominal power||100% of inverter nominal power|
DNOs require a fail-safe system, hard wire communications between the components of the export limitation system, specific power quality and operational time. The SMA export limitation system meets all DNO requirements.
Combined with highly efficient SMA inverters, the SMA Cluster Controller is the central communication unit for system monitoring, recording data and controlling large-scale PV plants.
The Sunny Home Manager is the ideal solution for smart energy management thanks to its standard access to Sunny Portal. It provides an overview of all important energy flows, automatic load control and storage system integration.
The SMA Energy Meter takes phase-exact and balanced electrical measured values as a grid feed-in and purchased electricity meter and communicates these values via Speedwire.
The versatile specialist for large-scale commercial and industrial plants: The Sunny Tripower 20000TL/25000TL not only delivers extraordinarily high yields with an efficiency of 98.5%, but also offers enormous design flexibility and compatibility with many PV modules, thanks to its multi-string capabilities and wide input voltage range.
SEE DETAILS HERE
The Sunny Tripower 15000TL has new, cutting-edge features: The integration of grid management functions, including Integrated Plant Control, allows the inverter to regulate reactive power at the grid-connection point. This means that upstream regulator units are no longer needed, and system costs are lowered. Another innovation is around-the-clock provision of reactive power (Q on Demand 24/7).
SEE DETAILS HERE
The specialist for medium-sized residential PV systems: Our ultramodern three-phase inverter, the Sunny Tripower, meets the highest technological requirements and comes in different power classes up to 12 kW.
As an ideal inverter for small and medium-sized households, the Sunny Boy TL is already ensuring high yields in thousands of PV systems worldwide. It is not only available in different power classes, but also for different roof designs. Thanks to the right communications technology, such as SMA’s Webconnect integrated into the inverter, this data can also be accessed online.
A dairy farm in Bristol required a PV installation with export limitation. They wanted to place an installation of 50 kWp, while the grid was limited to 11 KVA. As SMA has solutions for both, we were very happy to work together with the installer and DNO for the installation and witness test of the system.
|Plant size:||50 kWp, limitation to 27% of the Maximum Rated AC Power|
|Witness test date:||28 October 2015|
|Annual yield approx:||53.2MWh annually|
|CO2 reduction approx:||28 tons of CO2/year|
|Inverters:||2 x SMA Sunny Tripower 20000TL-30|
|Monitoring & Control:||Cluster Controller and SMA Energy Meter|
|DNO:||Western Power Distribution (WPD)|
Solarsense installed the PV system and added the SMA export limitation system with the Cluster Controller and the SMA Energy Meter. SMA provided Solarsense with technical support for setting up the export limitation system. Both the end user and the installer were very pleased with the results of the system. Solarsense is now looking into installing more plants with the same configuration and export limitation.
The DNO, had a long list of requirements for PV installations with export limitation. However, they were very impressed with the SMA export limitation system with the Cluster Controller and SMA Energy Meter.
An advantage for SMA is that we now know the issues the installers may find and the sort of tests the DNO will perform. With the information gained from this test, we are now fully prepared to support end users, installers and DNOs interested in export limitation.
The SMA Solar Academy regularly gives webinars on SMA’s export limitation system. You can find information on this new webinar and the upcoming dates here.