diff --git a/tools/esp8266/hmInverter.h b/tools/esp8266/hmInverter.h
index ca1e1bb6..321dec50 100644
--- a/tools/esp8266/hmInverter.h
+++ b/tools/esp8266/hmInverter.h
@@ -80,6 +80,7 @@ class Inverter {
         RECORDTYPE    *record;  // pointer for values
         uint16_t      chMaxPwr[4]; // maximum power of the modules (Wp)
         char          chName[4][MAX_NAME_LENGTH]; // human readable name for channel
+        bool          initialized; // needed to check if the inverter was correctly added (ESP32 specific - union types are never null)
 
         Inverter() {
             ts = 0;
@@ -87,6 +88,7 @@ class Inverter {
             powerLimit[1] = 0x0000; // 
             devControlRequest = false;
             devControlCmd = 0xff;
+            initialized = false;
         }
 
         ~Inverter() {
@@ -101,6 +103,7 @@ class Inverter {
             memset(name, 0, MAX_NAME_LENGTH);
             memset(chName, 0, MAX_NAME_LENGTH * 4);
             memset(record, 0, sizeof(RECORDTYPE) * listLen);
+            initialized = true;
         }
 
         uint8_t getPosByChFld(uint8_t channel, uint8_t fieldId) {
diff --git a/tools/esp8266/hmSystem.h b/tools/esp8266/hmSystem.h
index c2a7e28a..1070445a 100644
--- a/tools/esp8266/hmSystem.h
+++ b/tools/esp8266/hmSystem.h
@@ -91,7 +91,7 @@ class HmSystem {
 
         INVERTERTYPE *getInverterByPos(uint8_t pos, bool check = true) {
             DPRINTLN(DBG_VERBOSE, F("hmSystem.h:getInverterByPos"));
-            if((mInverter[pos].serial.u64 != 0ULL) || false == check)
+            if((mInverter[pos].initialized && mInverter[pos].serial.u64 != 0ULL) || false == check)
                 return &mInverter[pos];
             else
                 return NULL;