diff --git a/PLC/GVLs/GVL_CONFIG.TcGVL b/PLC/GVLs/GVL_CONFIG.TcGVL
index 8eee4d3..ea76357 100644
--- a/PLC/GVLs/GVL_CONFIG.TcGVL
+++ b/PLC/GVLs/GVL_CONFIG.TcGVL
@@ -10,6 +10,8 @@ VAR_GLOBAL CONSTANT
 	uiNumberOfUnits : UINT := uiNumberOfStrings * 12;
 END_VAR
 VAR_GLOBAL PERSISTENT
+	axStringEnabled : ARRAY [0..uiNumberOfStrings-1] OF BOOL;	
+
 	// ===========================
 	// Unit hardware config
 	// ===========================
diff --git a/PLC/POUs/MAIN.TcPOU b/PLC/POUs/MAIN.TcPOU
index 070924c..620fb46 100644
--- a/PLC/POUs/MAIN.TcPOU
+++ b/PLC/POUs/MAIN.TcPOU
@@ -156,6 +156,9 @@ VAR
 	_fbPowerMeterPower : FB_PowerMeter;
 	_fbPowerMeter24V : FB_PowerMeter;
 	
+	// Number of activated strings (from configuration)
+	_uiNumberOfActiveStrings : UINT;
+	
 	_xGetPowerMeterData : BOOL;
 END_VAR
 ]]></Declaration>
@@ -306,7 +309,7 @@ _tonStartupDelay(IN := TRUE);
 
 // Call string 1
 _afbStrings[0](
-	xEnable := _xEnableString,
+	xEnable := _xEnableString AND GVL_CONFIG.axStringEnabled[0],
 	uiStringNumber := 0,
 	xErrorShutdown := _xErrorShutdown,
 	xStartBalancing := _xStartBalancing,
@@ -335,7 +338,7 @@ GVL_MODBUS.stBMSErrorReg.wBMSWarningActive.stBitmap.bSafetyIntlkString1 := (NOT
 
 // Call string 2
 _afbStrings[1](
-	xEnable := _xEnableString,
+	xEnable := _xEnableString AND GVL_CONFIG.axStringEnabled[1],
 	uiStringNumber := 1,
 	xErrorShutdown := _xErrorShutdown,
 	xStartBalancing := _xStartBalancing,
@@ -380,8 +383,18 @@ _rMinCurrentInverterDCVoltage := 10_000;
 _rHighestSegmentVoltage := 0.0;
 _rSmallestSegmentVoltage := 1_000.0;
 _xStringsInAutoMode := TRUE;
+_uiNumberOfActiveStrings := 0;
+_rStringsSumVoltage := 0;
 
 FOR _ui := 0 TO (GVL_CONFIG.uiNumberOfStrings-1) DO
+	// Ignore deactivated strings
+	IF (NOT GVL_CONFIG.axStringEnabled[_ui]) THEN
+		CONTINUE;
+	END_IF
+	
+	// Count number of active strings
+	_uiNumberOfActiveStrings := _uiNumberOfActiveStrings + 1;
+	
 	// Check ready state
 	IF (NOT _afbStrings[_ui].xReady) THEN
 		_xStringsReady := FALSE;
@@ -437,6 +450,9 @@ FOR _ui := 0 TO (GVL_CONFIG.uiNumberOfStrings-1) DO
 		_rHighestSegmentVoltage := _afbStrings[_ui].rHighestSegmentVoltage;
 	END_IF
 	
+	// Calculate sum voltage
+	_rStringsSumVoltage := _rStringsSumVoltage + _afbStrings[_ui].rCurrentVoltage;
+	
 	// Get auto mode status
 	IF NOT _afbStrings[_ui].xAllModulesInAutoMode THEN
 		_xStringsInAutoMode := FALSE;
@@ -446,7 +462,7 @@ END_FOR
 // ===============================
 // Calculate sum power for string balancing
 // ===============================
-_rStringsSumVoltage := _afbStrings[0].rCurrentVoltage + _afbStrings[1].rCurrentVoltage;
+// _rStringsSumVoltage := _afbStrings[0].rCurrentVoltage + _afbStrings[1].rCurrentVoltage;
 
 
 // ===============================
@@ -928,20 +944,22 @@ _fbPowerMeter24V();]]></ST>
 END_CASE
 
 // Calculate string power balancing
-IF _rStringsSumVoltage <> 0 AND (GVL_CONFIG.uiNumberOfStrings <> 0) THEN
+IF _rStringsSumVoltage <> 0 AND (_uiNumberOfActiveStrings <> 0) THEN
 	FOR _ui := 0 TO (GVL_CONFIG.uiNumberOfStrings-1) DO
-		// Calculate delta u to middle voltage
-		_rDeltaUm := (_afbStrings[_ui].rCurrentVoltage * GVL_CONFIG.uiNumberOfStrings - _rStringsSumVoltage) / _rStringsSumVoltage;
-		
-		// Discharging
-		IF _rPowerInverter > 0 THEN
-			_arPowerString[_ui] := (_rPowerInverter / GVL_CONFIG.uiNumberOfStrings) * ( 1 + (_rDeltaUm * GVL_CONFIG.rBalancingFactor));
-		// Charging
-		ELSIF _rPowerInverter < 0 THEN
-			_arPowerString[_ui] := (_rPowerInverter / GVL_CONFIG.uiNumberOfStrings) * ( 1 - (_rDeltaUm * GVL_CONFIG.rBalancingFactor));
-		// Nothing
-		ELSE
-			_arPowerString[_ui] := 0.0;
+		IF GVL_CONFIG.axStringEnabled[_ui] THEN
+			// Calculate delta u to middle voltage
+			_rDeltaUm := (_afbStrings[_ui].rCurrentVoltage * _uiNumberOfActiveStrings - _rStringsSumVoltage) / _rStringsSumVoltage;
+			
+			// Discharging
+			IF _rPowerInverter > 0 THEN
+				_arPowerString[_ui] := (_rPowerInverter / _uiNumberOfActiveStrings) * ( 1 + (_rDeltaUm * GVL_CONFIG.rBalancingFactor));
+			// Charging
+			ELSIF _rPowerInverter < 0 THEN
+				_arPowerString[_ui] := (_rPowerInverter / _uiNumberOfActiveStrings) * ( 1 - (_rDeltaUm * GVL_CONFIG.rBalancingFactor));
+			// Nothing
+			ELSE
+				_arPowerString[_ui] := 0.0;
+			END_IF
 		END_IF
 	END_FOR
 ELSE