Description

Used product. Original KOSTAL PIKO DC-TRENNSTELLE electronic board, namely the electronic board of the DC disconnect/interruption section of the KOSTAL PIKO photovoltaic inverter. This is not simply a manual switch: the PCB electronically manages the connection and disconnection of the DC photovoltaic strings through power relays and dedicated power supply, control, and driver circuits.
The photographed board is in the 3-String configuration and features three power relays, three IN/OUT connection sections, a switching power supply circuit, transformers, protection components, and electronic control circuits.

⚙️ Technical Specifications

• Manufacturer: KOSTAL
• Type: DC-TRENNSTELLE
• Function: electronic board for DC circuit disconnection and management
• Photographed configuration: 3-String
• Power relays: 3
• Power connections: IN / OUT sections
• Connectors: X2, X3, X5, X6, X7
• Auxiliary power supply: integrated on the PCB
• Relay control circuit: integrated
• Switching power supply: integrated
• Transformer: present
• Electrolytic capacitors: present in the power supply section
• Diodes and protection components: integrated
• Control ICs: present on the board
• Construction: industrial PCB with power supply, control, and DC section disconnect circuits.

⚡ Function in the Photovoltaic System

The DC-Trennstelle is the electronic section of the inverter responsible for enabling or interrupting the DC current path coming from the photovoltaic strings.
During KOSTAL PIKO startup, the board receives its auxiliary power supply and manages the control sequence of the DC relays. Correct operation of the board therefore allows the voltage coming from the photovoltaic panels to be correctly managed and transferred to the subsequent inverter sections.
A malfunction of the DC-Trennstelle can therefore prevent the PIKO from completing startup even when photovoltaic voltage is present.

🔧 Faults, Errors & Symptoms

A fault in the DC-Trennstelle may be particularly associated with startup and DC circuit enabling problems.
Possible symptoms include:

• inverter remaining “Aus / Off”;
• DC voltage from the panels present but startup failing;
• DC relays failing to switch;
• relays producing repeated clicks during startup;
• failure to complete the initialization sequence;
• “XXX” displayed during the startup phase;
• DC/AC values not correctly available on the display during initialization;
• LEDs behaving abnormally;
• inverter failing to perform a normal restart;
• intermittent operation;
• failure to correctly transfer DC voltage to the subsequent stage.
  In particular, the condition in which the PIKO remains switched off or displays “XXX” despite photovoltaic voltage being present is a symptom compatible with a DC-Trennstelle problem.
  Important: “XXX” does not exclusively identify a DC-Trennstelle fault. The same behavior can be caused by other inverter sections; diagnosis must therefore be performed by checking the entire system.

🛠️ Component-Level Faults & Repair

The DC-Trennstelle can be repaired at electronic component level, making it a particularly interesting replacement for recovering PIKO inverters of this generation.
Among the components to be checked in the power supply section are particularly important:

• C4 – electrolytic capacitor, subject to loss of capacitance with aging;
• D10 – diode in the power supply/switching section;
• other electrolytic capacitors;
• diodes and protection components;
• switching circuit transistors;
• power supply transformer;
• auxiliary power supplies;
• relay driver circuits;
• coils and contacts of the three relays;
• solder joints and tracks;
• connectors and wiring;
• control and feedback circuits.
  A degraded C4 capacitor can cause unstable power supply to the board and prevent correct relay energization. Problems associated with D10 in the same electronic section have also been documented.
  Repair can therefore be aimed at restoring conditions such as startup failure, relays not switching, intermittent startup, and incorrect management of the DC circuit.

🌐 Compatibility & Applications

The board belongs to the family of DC-Trennstelle boards used in first-generation KOSTAL PIKO DCS.
It is used in various versions of the KOSTAL PIKO series, including:

• PIKO 3.0
• PIKO 3.6
• PIKO 4.2
• PIKO 5.5
  Compatibility must nevertheless be verified before replacement by comparing the inverter model, PANEL, BOARD, board revision, and string configuration.

🏭 Construction & Product Condition

The board is used and shows normal signs resulting from previous installation and handling.
The photographs show the main DC-Trennstelle components, including the three power relays, transformer, switching circuit, capacitors, diodes, integrated circuits, connectors, and wiring.
The PCB appears structurally intact from the photographs and shows no evident extensive burns or generalized damage.

🛡️ Safety

The DC-Trennstelle operates directly in the photovoltaic DC section of the inverter, where high and potentially lethal voltages may be present even with the AC grid disconnected.
Replacement, repair, and testing must be performed exclusively by qualified personnel, using the correct safety procedures for securing the inverter and photovoltaic generator.
After work on the board, insulation, connections, tightening, revision compatibility, and operation of the complete inverter must be correctly verified.

📦 Package Contents

1 × original KOSTAL PIKO DC-TRENNSTELLE electronic board, as shown in the photographs.

🚀 Final Description

The KOSTAL PIKO DC-Trennstelle is the electronic board of the inverter's DC disconnect section, responsible for the electronic management of the photovoltaic strings and control of the related power relays.
The photographed PCB is a 3-String version with three relays, switching power supply circuitry, transformers, protection components, and control circuits. It is a particularly useful replacement for repairing KOSTAL PIKO inverters presenting an inverter switched off with PV voltage present, relays failing to switch, startup failure, intermittent restarts, or “XXX” displayed during the initialization phase.
For repair, particular attention should be given to the switching power supply, C4, D10, electrolytic capacitors, diodes, transistors, relays, and solder joints. Replacing faulty components may allow recovery of the DC-Trennstelle without necessarily replacing the entire board.