FAQ Steca Solarix PLI

  • Why do the fans turn permanently?
    The fans generally start as soon as the unit goes into operation. If the inverter is switched off and there is no PV energy, the lights and the display will remain off. As soon as the inverter is switched on via the ON/OFF switch or when PV energy is available, the display will switch on and the fans will also start. The fans always run at a constant speed. There is no speed control.
    Since the energy density of the Solarix PLI is very high, the fans always run at low speed to keep the air moving at about ¼ speed. The fans are PWM-controlled and operate proportionally to the power of the inverter. This cools the power components before any build-up of heat occurs. This provides the advantage of a longer service life for the components. This is because the average temperature of the components is lower throughout the life of the inverter, compared to a strategy where the fans operate only in response to a rise in temperature.

    This is why it is not recommended to install the unit in a residential area, for example, as the volume of the operating noise could be unpleasant.
  • What are the requirements for connecting a generator?
    Since the generator not only supplies the loads at the AC output but also recharges the battery in grid mode, it is generally recommended to use a generator that is 2 times the size of the inverter.

    Additional technical requirements of the generator:

    - Generator waveform THD: <30%.
    - If the generator outputs a square wave, output duty should be greater than 60%
    - Generator Vrms range: 100 ~ 270Vac
    - Generator voltage crest factor (Vpeak/Vrms): 1.6
    - Generator peak voltage: 380V
    - Generator frequency range: 45Hz ~ 63Hz
    - Generator frequency slew rate: < 0.3Hz/sec
  • Why does the PLI not accept the grid connected to the AC input?
    The PLI cannot stabilise the network in this sense, instead it either accepts it or not. There are 3 modes of operation:

    1. No voltage at the AC input, a voltage below 170 Vac (in UPS mode) or above 280 Vac, or a frequency below 40 Hz or above 65 Hz.

     The islanding inverter in the PLI operates independently of the grid at 230 Vac/50 Hz
    2. The AC input has a voltage within 170 – 280 Vac and within 40 – 65 Hz. However, the grid is not connected due to the parameters of the PLI (bypass relay is open).

     The islanding inverter in the PLI operates with a stable 230 Vac and exactly the same frequency as the grid. It is therefore synchronised with the grid (in terms of frequency)
    3. The AC input has a voltage within 170 – 280 Vac and within 40 – 65 Hz. The grid is connected, i.e. the bypass relay is closed.

     The grid is now simply ‘passed through’; the consumers are connected directly to the grid via the bypass relays. As long as the grid operates within the voltage and frequency window, it is essentially ‘accepted’ by the PLI and not stabilised in any way. However, the grid is disconnected as soon as the voltage or frequency goes outside of these windows.

    Whether the batteries may be charged from the grid is defined in programme 16 ‘Priority of charging source’. It is never possible to charge the battery from the grid and operate the PLI in battery mode at the same time. If charging is currently taking place from the grid, the loads must also be supplied directly from the grid via the bypass relays. It would also not make much sense to charge the battery from the grid and discharge the battery at the same time in order to supply the consumers via the inverter (poor efficiency level). This is technically impossible because the islanding inverter is also the charger and can only either charge from the grid or act as an islanding inverter in battery mode, but cannot do both at the same time (which would also not be permitted under the standards, because then it could theoretically feed into the grid).
  • What is the maximum cross-section of the connecting cables?
    Maximum cable cross-sections:

    AC terminal 3 pin M4 max 6mm²   All versions
    DC terminal 2 pin M5 max 6mm²   PLI 2400-2424
    DC terminal 2 pin M5 max 10mm²   PLI 5000-48
  • How loud is the operating noise of the units?
    At idle:  36 dB
    Under full load: 58 dB

    Measurement 1 m from the unit.
  • PLI5000-48: Can a load larger than 5KW be operated in bypass mode?
    When the AC grid is available and the inverter is operating in AC mode, the inverter can bypass the AC grid to output up to 40 A of current, which is approximately 8800 W. The inverter can also bypass the AC grid. However, when the inverter is operating in inverter mode, the maximum power is limited to 5 KW.
  • Are the settings lost when the unit is disconnected from the battery?
    The settings are stored in the EEPROM without using the battery. If the battery has not been charged by the PV or AC grid for a long time, we recommend disconnecting the battery from the inverter. This has no influence on the customised settings.
  • PLI5000-48: Can lithium battery storage be used with the inverter?
    At the present, we can confirm compatibility with certain lithium battery storage units from the manufacturer Pylontech. 

    Please note the following documentation.

  • PLI5000-48 What is the self-consumption during the different system states?
    Battery mode without load: 53 W
    Standby mode 10W
    Energy saving mode: <10W
    Bypass mode: 0.6W 
    Grid operation with full battery: 50W

  • What needs to be considered regarding the operating temperature?
    The operating temperature specified in the PLI manual refers to the ambient temperature in which the inverter can be used:
    Operating temperature: 0°C to 55°C, power reduction (derating) from 40°C

    The internal temperature sensors are located on the radiators. If the temperature measured exceeds 100°C, the error 02 ‘excess temperature’ is triggered.
    When used outside the operating temperature, or if the air supply/exhaust is blocked, the temperature at the coolers of the charge controller and inverter can rise to this level.
  • Why is Programme 28 not accessible, or what is it used for?
    Programme 28 is only required when using several units with the help of the parallel kits (available separately).

    This setting can only be made when the inverter is in ‘standby mode’. Operate the inverter only in battery mode.
    1) Main switch to ‘On’
    2) Main switch to standby mode ‘Off’, then the display remains on for approx. 30 seconds and during this time the menu item ‘28’ can be set
    3) Main switch back to ‘On’
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