@michael-rudek Lol, well that does make a difference! 
Above mentioned sketch still gives me weird readings. However, i found another sketch and now i see readings that start to make some sense.
With nothing plugged in, I get:
sensor_max = 385 (rises to 386 sometimes)
The amplitude of the current is(in mA) -6201.2
The effective value of the current is(in mA) -4385.6
With power usage according to power consumption meter:
385 watt (1,687 A, voltage 228)
sensor_max = 422 (rises to 423 sometimes)
The amplitude of the current is(in mA) -4394.5
The effective value of the current is(in mA) -3107.9
Now i would have to find a way to calculate the difference between the sensor_maxes, telling me the power usage is 385 watt.
The sketch I’m currently using:
#define CURRENT_SENSOR A0 // Define Analog input pin that sensor is attached
float amplitude_current; // Float amplitude current
float effective_value; // Float effective current
void setup()
{
Serial.begin(9600);
pins_init();
}
void loop()
{
int sensor_max;
sensor_max = getMaxValue();
Serial.print("sensor_max = ");
Serial.println(sensor_max);
//the VCC on the Arduino interface of the sensor is 5v
amplitude_current=(float)(sensor_max-512)/1024*5/100*1000000; // for 5A mode(185),you need to modify this with 20 A (100) and 30A (66) mode;
effective_value=amplitude_current/1.414;
//for minimum current=1/1024*5/185*1000000/1.414=18.7(mA)
//Only sinusoidal alternating current
Serial.println("The amplitude of the current is(in mA)");
Serial.println(amplitude_current,1);
//Only one number after the decimal point
Serial.println("The effective value of the current is(in mA)");
Serial.println(effective_value,1);
}
void pins_init()
{
pinMode(CURRENT_SENSOR, INPUT);
}
/*Function: Sample for 1000ms and get the maximum value from the S pin*/
int getMaxValue()
{
int sensorValue; //value read from the sensor
int sensorMax = 0;
uint32_t start_time = millis();
while((millis()-start_time) < 1000) //sample for 1000ms
{
sensorValue = analogRead(CURRENT_SENSOR);
if (sensorValue > sensorMax)
{
/*record the maximum sensor value*/
sensorMax = sensorValue;
}
}
return sensorMax;
}
I’m not too experienced with electronics. The ultimate goal with this little project is to measure the output of my solar invertor, since the Mastervolt intelliweb server goes annoyingly down about every sunny day.