FAQ

Our development team has worked incessantly to turn the BSP into the central brain of our Xtender system. We have improved the robustness of the central battery charge current control. When activated, the BSP manages the global battery charge current, measured directly by the BSP in the battery, and controls the VarioString, Variotrack and Xtender charge currents. This control will implicitly apply a solar priority strategy. Thus, the current will be taken primarily from Variotrack and VarioString. For further information, please see our BSP manual available in the Accessories User Manual section from the Downloads section.

Did you know that a list of more than 220 messages accompanied by a troubleshoot description are available in our product manuals?

For instance, in our demo installation we received the following message (170):

Looking into the RCC Quickguide or the VarioString Manual we are able to identify the following information:

Please check our products manuals and the RCC quickguide for further information.

The Xtender can be operated with any earthing system. In all cases it is imperative that the protective earth is connected in compliance with the applicable standards and regulations. The information, notes, recommendations and diagrams mentioned in the manuals are always subject to local installation regulations. The installer is responsible for the conformity of the installation with the applicable local standards.

The Xtender has a different role when there is an AC source connected or when operating off-grid.

In case the Xtender is connected to a source (generator, grid), the Xtender synchronizes with the AC input and closes the transfer relay. The Xtender is just a bridge from AC-input to AC-output. In this case, the earthing strategy from the source is then transferred to the output and there is no need to configure anything in the Xtender.

When off-grid, the Xtender is forming the grid with energy from the battery, using the inverter function. In this case the Xtender is the source and we should configure the earth according to the desired strategy.

In most applications, the source should have the neutral connected to the ground, especially if there are residual current circuit breakers (RCCB) installed. There are two options for configuring the neutral to the ground in the Xtender:

• Xtender ground relay (1485)  

By allowing the ground relay, the Xtender will automatically connect the neutral to earth in the AC-output, when the Xtender is off-grid in the inverter function.

This relay is automatically open (no more liaison between neutral and the earth within the Xtender) when the Xtender is connected to a source. The earth strategy is coming from AC-in, from the grid or generator.

• Continuos neutral from AC-in to AC-out (1486)

For stationary applications, we can configure the Xtender to tie the AC-in neutral with the AC-out neutral. There is an AC-in continuous reference (grid or generator) and the neutral is always transferred to the AC-output. In this configuration, the transfer relay will open only the AC-input phase, leaving the neutral connected, when the Xtender is on inverter function. 

Both strategies are not compatible to be configured simultaneously, the installer should choose one. We recommend configuring the ground relay (1485) for most applications and continuous neutral (1486) for stationary applications. If none of these strategies is configured, the installation will not have the neutral referenced to the ground when the Xtender is off-grid. This could lead to a not proper functioning of the RCCB devices in the installation.

Studer Innotec SA is an equipment manufacturer, not an installer, integrator or electrical specialist. Please check the local regulations and contact with a specialist on the field for an assessment.

Similar to AC, we recommend contacting a specialist for an assessment on DC earthing: battery and/or PV solar generator.

There are the following standardized earthing schemes, according to the Electrical Installation Wiki, depending on the earthing strategy in the source and in the exposed protective parts:

TT Source neutral = T Exposed conductive = T T = Terra (latin), earth
TN-C Source = T Exposed conductive = N Neutral is protective conductor (C)
TN-S Source = T Exposed conductive = N Protective conductor and neutral separate (S)
IT Source = I Exposed conductive = T No connection between neutral and earth in the source

The dimensioning of the solar generator is crucial for having enough energy to charge the battery and supply energy to the loads. The configuration of the solar array must be done according to the voltage and current limits of the VarioTrack (VT).

To get the optimum solar voltage the PV modules should be connected in series to form a string with the desired voltage. The optimum operating voltage of the string (Vmpp) should always be above the battery voltage. The maximum operating voltage must always be lower than 145Vdc, under any temperature and irradiation condition. This value should be calculated according to the modules open circuit voltage with the temperature correction for the lowest temperature expected for the installation.

For example, if we are working with a 60 cells PV module with the following characteristics:

• Open circuit voltage, V_oc = 39,1V_dc (at STC, 25°C)
• Thermal coefficient for V_oc, β_Voc = -0.33 %/°C

For this module the open circuit voltage at -10°C (lowest temperature of your installation) will increase by 11.55% up to 45.16V_dc. Therefore, it is possible to install up to 3 of these modules in series for this installation, in order to respect the maximum of 145Vdc of the VT-80.

Thus, we have a maximum of 3 standard modules (60 cells) per string in our typical configuration for 24 and 48V batteries.

Possible arrangement in series for common PV panels according to the number of cells and type

The voltage calculation is critical, as a potential voltage above 145V will damage the device and may cause fatal defects in the installation.

In terms of power, several strings are usually connected in parallel. Each string connected in parallel should be composed of the same number of modules of the same type. The number of strings connected in parallel will determine the solar charging current. The VT has a current limit: 65 Amps for VT-65 and 80 Amps for VT-80. This will be the maximum current that the VT is able to take from the solar array towards the battery. If the number of strings in parallel is increased, the VT will reach its maximum charging current quicker and even when solar irradiation is lower. This will also mean that there would be a bigger potential of energy that will not be used when the solar irradiation is high. As soon as the voltage limit is respected, the solar power to be installed depends on the dimensioning of the installation. Thus, it is possible to oversize the solar power to maximize the solar production, even if this means an increase of potential solar energy not used.

 

 

In terms of irradiance this could be relevant, for example in European countries, during most of the year the solar production is lower than the nominal power because of low irradiation (winter, clouds, etc.). If we take the example of our factory in Switzerland, we could have a 10% over dimensioning in solar power, which will represent a very little excess of solar (solar not used) during summer, but a 10% increase in the production all over the rest of the year:

 

 

In addition, there are other weather and context conditions that could drastically influence your solar production and that you should consider (such us dust, air particles, pollution, snow, shadows, etc.). For example, in countries where there is snow during the winter, the dimensioning should consider the reflexion (albedo) can be quite high and the irradiance on the solar modules can be higher than the standard test value of 1000W/m2, influencing the Voc and Isc values of the modules in winter.

The Scom Web Service is the Application Programming Interface (API) for easily integrating the data from your Xtender installation in your web-based platform. 

The Scom webservice "https://xcom.studer-innotec.com/scomwebservice.asmx" is available with the following functions:

1. List of the installations registered by the client (GetInstallationList)
2. Messages from one installation (GetMessages)
3. Reading of one parameter (ReadParameter)
4. Reading of a real time information (ReadUserInfo)
5. Changing one parameter (WriteParameter)

The functions "GetDatalogValues" and "GetRemoteScreen" are not available. There is a "Datalog File Provider Service" available, further description could be provided upon request.

Please find below an example of request/response using the different functions available:

In a hybrid system is very important to have an automatic management of the backup generator, according to different conditions. The main goal of the backup generator is to protect the battery from deep discharge. At Studer we know that the protection of the battery is critical, therefore we have preconfigured the automatic start of a generator according to battery voltage using the Xtender's Auxiliary Contact 1 as factory settings. You only need to cable the Xtender's Auxiliary Contact 1 and the generators' automatic start. The preconfigured factory settings will do the rest, starting your generator when the battery voltage is low. When your battery is charged, the Auxiliary Contact 1 will be deactivated and your generator will turn off automatically.

Your Xtender system is prepared from the factory for an easy integration of a backup generator to protect your battery. The battery voltage conditions are preconfigured by us. We recommend adjusting the battery voltage values according to your system design and the battery manufacturer recommendations. Configuring the Xtender to automatically start the generator according to other conditions and events is also possible in the Xtender settings menu.

Most generators have an automatic start available. If you have a generator with a three-wire contact, you can still configure the system for an automatic start of generator, using the extended functions of the Auxiliary Contacts 1 and 2.

There is a wide range of battery technologies available for energy storage applications. Studer devices are compatible with all battery types, including lithium batteries. While with the other battery types, adapting the configuration of the battery management cycle to the battery specifications is enough, with lithium batteries the communication plays a key role. Lithium batteries differentiate from other batteries by having an integrated Battery Management System (BMS).

There are two types of Lithium batteries:

1) Lithium batteries with communication

Most lithium batteries require communication between their BMS and the rest of the system for an optimal management of the battery (safety and lifetime). Every battery has its own specific protocol to communicate. The Xcom-CAN works as a bridge between the BMS and the Studer bus. It has several protocols implemented for Lithium battery management, which are compatible with a list of specific batteries. Please check our website for an updated list of compatible manufacturers.

When connected to an Xcom-CAN, the BMS takes over the control of the battery management, which is no longer available in the Xtender, Variotrack or Variostrings settings menu. The battery management information is sent from the BMS to the Xcom-CAN, which will steer the Studer devices adjusting their configuration accordingly.

Having a communicating BMS makes the system smart, enabling us to facilitate the configuration of the main functionalities of the system with a list of parameters unique for lithium batteries.

The configuration of an Xtender system with lithium batteries and an Xcom-CAN can be easily done using the following parameters: SOC for backup {6062} and SOC for grid feeding {6063}

For further information on how to configure an Xtender system with Lithium batteries, please see our Xcom-CAN manual (Accessories user manuals).

2) Lithium batteries without communication

Some lithium batteries with an integrated BMS do not need communication. These batteries will require a configuration of the battery management cycle as requested by the battery manufacturer. Our configuration assistant can guide you through this configuration. Selecting Lithium as battery type and choosing the right capacity is usually enough.

Please confirm with the battery manufacturer that these settings are suitable for your lithium battery. The battery management settings can be adjusted according to battery manufacturer specifications in the Xtender settings menu on your RCC.

In a grid-connected system, it is possible to feed excess solar energy into the grid, if grid injection is authorized. Please confirm with the local regulation and utility directives if grid feeding is allowed in your country and for your specific situation. 

There are two possible configurations for the grid feeding function:

1) Standard grid feeding

In this configuration, the system will inject excess energy from the solar system to the grid. The solar energy is used first to supply loads and charge the battery. Additional energy is injected to the grid, only when the battery is in absorption or floating phase.

*The maximum current of the source is respected {1107} (Input limit).

2) Forced grid feeding

With the forced grid feeding it is possible to discharge the batteries towards the grid during a given time frame. Thus, between the start time {1525} and the stop time {1526}, the Xtender will feed current from the batteries to the grid, discharging the batteries up to {1524} Battery voltage target for forced grid feeding.

*To be adjusted to the desired value.

Grid feeding regulation

The grid feeding function will apply the frequency control strategy, reducing linearly the feeding current when the frequency is above the nominal frequency of the inverter. In addition, this function has a protection for limiting the power when the grid voltage is too high.

Please check our RCC manual for further description on the configuration of this limit and control.

Grid feeding with AC Coupling

The grid feeding function from the Xtender is only related to the energy fed into the grid by the Xtender from the DC side (battery). In a system with a solar inverter coupled in AC, the grid function from the Xtender does not control or limit the energy fed into the grid by the solar inverter. For this, an external controller will be required. Please check the following description for configuring AC coupled system and contact us for further assistance.

 

AC Coupling is a term used to describe systems that combine grid-tie inverters (usually feeding all energy produced to the grid) and battery-based inverters (usually for off-grid or backup applications).

Grid-tie inverters or solar inverters convert the variable direct current (DC) output of a photovoltaic (PV) solar panels into a utility frequency alternating current (AC) that can be fed into a commercial electrical grid or be used by a local, off-grid electrical network. A grid-tie inverter synchronizes with an existing sine wave (grid) and shuts down upon a grid failure.

Today many manufacturers have included "frequency shift" behaviour on their grid-tie inverters. This allows the grid-tie inverters to reduce their power output depending on the grid frequency.

Figure 1 Frequency shift behaviour from SMA

One or various solar grid-tie inverters can be installed in an Xtender system, coupled on AC. The system will work as described below:

1) AC Coupling with a Xtender Off-grid system

When off-grid, the Xtender is forming the grid with energy from the battery, using the inverter function. In this case, a solar inverter can be connected on the AC output of the Xtender. It will synchronize with the grid created by the Xtender and will feed its solar production into the grid to supply the loads and charge the battery.

When there is an excess of solar production and the batteries are full, the system will need to limit the solar production. We can use the frequency control function from the Xtender, that will increase the frequency of the AC output according to the battery voltage. When the battery is fully charged, the solar inverter will stop its production, thus both the battery and the system are perfectly secured.

The frequency control function is activated by setting the parameter 1549 "Inverter frequency increase according to battery voltage" to YES.

2) AC Coupling with an Xtender connected to the grid

When connected to the grid, the Xtender will synchronize with it and close the transfer relay. In this case the Xtender acts as a current source inverter. Both the voltage and frequency are set by the grid and the Xtender synchronizes with them and exchange current.

The solar inverter connected in the system, will feed solar energy that will be used directly by the loads and to charge the battery through the Xtender. In this case, the Xtender can't do any frequency control (the grid is controlling the frequency), therefore, the excess of solar production from the solar inverter will be then fed into the grid.

3) AC Coupling with an Xtender connected to a generator

Similarly, as when the Xtender is connected to the grid, the Xtender connected to a generator will synchronize with it and close the transfer relay. Again, both the voltage and frequency are set by the grid and the Xtender synchronizes with them and exchange current.

The main limitation of this situation is that it is not possible to feed energy back to the generator, as it will damage the machine. For safety reasons, it is recommended to use the Xtender's Auxiliary contact to open a circuit-breaker isolating the solar inverter from the Xtender inverter when the generator is working. During times when the generator is not used, the system will work as described in the off-grid situation (1).

For grid connected systems, adding battery storage provides a back-up energy source in the case of grid failure. The Studer standard application maintains the battery fully charged and supplies loads using solar and grid energy. If grid injection is authorized, excess solar energy is exported to the grid. Otherwise, with standard settings, excess solar energy is not used.

With the self-consumption application, the Xtender system allows the battery to be discharged at night in order to store excess solar energy during the day, and thus increase the amount of solar energy consumed onsite.

The following options are available for configuring the self-consumption in your Xtender system:

Battery priority function

By activating this function (1296) there is a battery priority voltage (1297) as reference and the behaviour of the Xtender will be different if the battery voltage is above or below this level:

- Battery voltage above battery priority voltage

• The battery will be charged only with energy coming from Variotrack/Variostring (solar) and not from the grid.
• The AC-in input limit will be automatically reduced from the value set by the user (1107) to a minimum of 1Amp

- Battery voltage below battery priority voltage

• The battery will be charged from both Variotrack/Variostring (solar) and from the grid (AC-in). 
• The AC-in input limit remains fixed at the value set by the user (1107)

Advantages:

• The grid is always available to support in case of peak of demand on AC-out
• The Xtender is always at transfer/boost/charger function. There is no transition from one function to another

Disadvantages:

• There is always a minimum of 1 Amp consumed from the grid. It is not possible to reach 0 consumption from the grid.
• There is some excess of solar energy that will be not used

Grid as generator function

In this case we use the grid as if it was a generator. The Xtender will be off-grid as soon as the battery level is good (according to battery voltage). When the battery voltage reach a certain level (1245), the Auxiliary Contact 1 from Xtender will be activated. The Remote Entry will be automatically activated according to Auxiliar 1 status. The Remote Entry will allow the connection to grid by disabling the transfer relay prohibition (1538). 

Once the battery is charged and the battery voltage reaches the deactivation voltage (1255), the Auxiliary 1 will be desactivated, desactivating the Remote Entry and therefore forbidding the transfer relay again. The Xtender is again off-grid with 0 consumption from the grid.

Advantages:

• The self-consumption of solar energy is maximized in comparison to the first option.
• When the Xtender is off-grid the consumption from the grid is 0.

Disadvantages:

• There is a micro-shutdown (max. 15ms) during the transition from grid connected to off-grid.
• In case of peak of demand in off-grid mode, the Xtender will not have support from grid and risk of overload is higher.

Self consumption with Lithium Batteries

Additionally, when the Xtender works with Lithium batteries that are communicating through the Xcom-CAN bridge, the self-consumption could be easily configured thanks to the "SOC for backup" parameter (6062). For more information check the Xcom-CAN manual (Accessories user manual) or the FAQ for lithium batteries.

There are three communication solutions available for your Xtender system to communicate with the Studer Portal:

• Xcom-SMS

The communication device Xcom-SMS allows for connections to sites with a GSM (2G) coverage. A standard, local, prepaid SIM card provides a secured access to your remote Studer power system by sending or receiving an SMS. It is possible to use the Studer Xcom-SMS Access Android app.

• Xcom-GSM

The interface allows for remote interaction with the installation exactly as if on-site with the remote control RCC-02/-03, including: access to all parameters, real-time display of measured data of all devices included in the system and access to the last 30 days of log files. It includes a 3G Modem to insert your local SIM card with data package for GPRS or 3G internet connection.

• Xcom-LAN

The interface allows for remote interaction with the installation exactly as if on-site with the remote control RCC-02/-03, including: access to all parameters, real-time display of measured data of all devices included in the system and access to the last 30 days of log files. It includes a LAN Modem to connect with your LAN router for internet connection.

To use 4G or Satellite connection, the Xcom-LAN allows to connect a 4G Modem or Satellite Modem for the internet connection, instead of the LAN router. The 4G or Satellite modem are not provided by Studer Innotec.  

For further communication options please see our brochure for System Monitoring & Control.

Xcom Communication possibilities

Symptom

In a new installation, the Xcom-LAN has been configured following the manual instructions. The GUID is not found in the Xcom Portal and the Xcom-LAN does not work.

Solution

Please reconfigure the Xcom-LAN again, following all the steps (Xcom Configurator and reinserting the SD-card in the Xcom-232).

Disconnect the Studer Can Bus cable fom the Xcom232 and reconnect it again, it will reset the Xcom and Moxa)

The configuration will be finished only when the following message is received:

If the message "(090) Server connected" does not appear, there is either a configuration issue, an internet issue or a hardware issue.

Install Nport Search Utility and access to Moxa interface

Please go to the Moxa Nport 5110A website and download the Nport Search Utility from the Drivers & Software section (https://www.moxa.com/product/NPort_5110.htm)

1. Install the NPort Search Utility

Unzip and install NPort Search Utility included in the Zip folder.

2. Open Nport Search Utility

3. Search all devices by clicking on the "Search" button

4. Access the device through the contextual menu

5. Unlock the device by entering the password

Enter the password: xcomlan (default password)

Configuration issue

By default, the Xcom-LAN is in DHCP/BOOTP mode. You can set a static IP address by accessing the gateway (Moxa interface).

1. Click on " Network Settings " in the navigation bar
2. Change IP configuration from “DHCP/BOOTP” to “Static”
3. Set IP address, netmask, gateway and DNS server
4. Click on " Submit "
5. Click on " Save/Restart "

Internet/Network issue

If you are connected to a company network the TCP port 83 may be blocked due to security settings. Please change the outbound rule for this port.

Check the Network settings with your internet service provider.

Hardware issue

It is possible that the Moxa's TX counter is not working. If this counter is at zero, the Xcom's TX line is damaged and must be replaced. Please contact Studer Innotec support in order to replace your set.

Click on "Monitor" in the navigation bar, then click on "Async".

If the Rx counter is at 0, it means that the hardware is defective. Please send the full Xcom-LAN set (Xcom232, Moxa and serial cable) to Studer for repair.

If both Rx counter and Tx counter are at 0 and you have configured a static IP address, please confirm that your DNS server is public (e.g. 8.8.8.8 (Google) or 1.1.1.1 (Cloudefire))

A working communication between the Moxa and the Xcom232 will show values in Rx and Tx (information is sent and received):

Reset to factory settings and reconfiguration Xcom

Similar to other Studer devices, an Xcom's SW reset is possible in order to return the Xcom to factory settings. Please see the FAQ section for more information about SW reset.

When using an Xcom-LAN or Xcom-GSM, the user has an Xcom232 plus a LAN or GSM modem. After executing the Xcom Configurator, the Xcom232 will be then configured as Xcom-LAN or Xcom-GSM for working with the respective modem. When a SW reset is applied to an Xcom-LAN or Xcom-GSM, the Xcom will be then reconfigured again as Xcom232i with factory settings. Consequently, the Xcom Configuration process is required again, creating a new configuration and therefore a new ID for installation in the portal. This operation could lead to an excess use of data for recovering all the local data from the Xcom in the portal. Please be aware that this n could lead to a high data traffic and therefore unforeseen expenses in your data connection. A SW reset for an Xcom-LAN or Xcom-GSM is therefore not recommended unless it is a new installation or required by SW incompatibilities.

The latest software version is always available on our Studer website in the Software and Updates section.

A software reset may be necessary in case of errors or problems in the system, in order to restore the factory settings and update all the devices in the system with the same software version.

When you download the latest software release, you will have in the computer a zip folder containing:

Please modify the name of the folder 02 to 03. Then copy the 03 Folder into the SD card of your RCC or Xcom device and insert the card in the device.

The process will be then similar to the process described in the FAQ SW Update.

Please read carefully the Updating procedure (PDF) before performing the reset.

RCC

The RCC will beep when the SD card is correctly inserted. Then confirm the update by pressing ok. The update is completed when the RCC displays the message "The update is finished" (051).

Xcom

The Xcom will blink red when the SD card is coorectly inserted. The update will start automatically. The update is completed when the LED indicator is green.

The update should be performed in all the RCC and Xcom devices in the system (all the devices having an SD or microSD card). All Studer products in a system should have the same software version.

The latest software version is always available on our Studer webiste in the Software and Updates section.

A software upgrade may be necessary during system commissioning, when adding a device to an existing system, after a device has been serviced, or to take advantage of a new function or parameter. When in doubt, contact Studer Innotec before performing the software update.

When you download the latest software release, you will have in the computer a zip folder containing:

Please copy the 02 Folder into the SD card of your RCC or Xcom device and insert the card in the device.

Please read carefully the Updating procedure (PDF) before performing the update.

RCC

The RCC will beep when the SD card is correctly inserted. Then confirm the update by pressing ok. The update is completed when the RCC displays the message "The update is finished" (051).

Xcom

The Xcom will blink red when the SD is inserted. The update will start automatically. The update is completed when the LED indicator is green.

The update should be performed in all the RCC and Xcom devices in the system (all the devices having an SD or microSD card). All the Studer products in a syst

The system stores by default a daily logfile on the SD card of the RCC and/or Xcom device. However, in order to have a complete system backup, including the logfiles, the current configuration parameters and the system messages, the function "Save all files (system backup)" should be used. Please go to RCC settings and follow the next steps:  

Once the backup is finished, please take out the SD card from the RCC-02 console. Then you could copy all the folders and files in the SD card using a computer.

Please insert again the SD card in the RCC-02 console when the process is finalized.