diff --git a/include/Utils.h b/include/Utils.h
index b4387b8..dbcea81 100644
--- a/include/Utils.h
+++ b/include/Utils.h
@@ -6,4 +6,5 @@
 class Utils {
 public:
     static uint32_t getChipId();
+    static uint64_t generateDtuSerial();
 };
diff --git a/src/Utils.cpp b/src/Utils.cpp
index 17769b7..7fd090d 100644
--- a/src/Utils.cpp
+++ b/src/Utils.cpp
@@ -8,4 +8,27 @@ uint32_t Utils::getChipId()
         chipId |= ((ESP.getEfuseMac() >> (40 - i)) & 0xff) << i;
     }
     return chipId;
+}
+
+uint64_t Utils::generateDtuSerial()
+{
+    uint32_t chipId = getChipId();
+    uint64_t dtuId = 0;
+
+    // Product category (char 1-4): 1 = Micro Inverter, 999 = Dummy
+    dtuId |= 0x199900000000;
+
+    // Year of production (char 5): 1 equals 2015 so hard code 8 = 2022
+    dtuId |= 0x80000000;
+
+    // Week of production (char 6-7): Range is 1-52 s hard code 1 = week 1
+    dtuId |= 0x0100000;
+
+    // Running Number (char 8-12): Derived from the ESP chip id
+    for (uint8_t i = 0; i < 5; i++) {
+        dtuId |= (chipId % 10) << (i * 4);
+        chipId /= 10;
+    }
+
+    return dtuId;
 }
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index 0aa72ea..6004b44 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -7,9 +7,10 @@
 #include "MqttHassPublishing.h"
 #include "MqttPublishing.h"
 #include "MqttSettings.h"
-#include "NtpSettings.h"
-#include "WebApi.h"
 #include "NetworkSettings.h"
+#include "NtpSettings.h"
+#include "Utils.h"
+#include "WebApi.h"
 #include "defaults.h"
 #include <Arduino.h>
 #include <LittleFS.h>
@@ -76,9 +77,22 @@ void setup()
     WebApi.init();
     Serial.println(F("done"));
 
+    // Check for default DTU serial
+    Serial.print(F("Check for default DTU serial... "));
+    CONFIG_T& config = Configuration.get();
+    if (config.Dtu_Serial == DTU_SERIAL) {
+        Serial.print(F("generate serial based on ESP chip id: "));
+        uint64_t dtuId = Utils::generateDtuSerial();
+        Serial.printf("%0x%08x... ",
+            ((uint32_t)((dtuId >> 32) & 0xFFFFFFFF)),
+            ((uint32_t)(dtuId & 0xFFFFFFFF)));
+        config.Dtu_Serial = dtuId;
+        Configuration.write();
+    }
+    Serial.println(F("done"));
+
     // Initialize inverter communication
     Serial.print(F("Initialize Hoymiles interface... "));
-    const CONFIG_T& config = Configuration.get();
     Hoymiles.init();
 
     Serial.println(F("  Setting radio PA level... "));