How to convert char array to String in arduino?
you can use a cast to __FlashStringHelper to invoke the right constructor of the String class. It is the constructor which copies the char array from PROGMEM. __FlashStringHelper is intended as return type for the F() macro.

const char charArray[] PROGMEM = "Some text";

void setup() {

  Serial.begin(115200);

  String s((const __FlashStringHelper*) charArray);

  Serial.println(s);
}

void loop() {
}