Добавления массива структур в класс

Сделал вот так

#ifndef SENSORMANAGER_H
#define SENSORMANAGER_H
#include <QObject>
class SensorManager : public QObject
{
Q_OBJECT
private:
struct Bal{
unsigned short int Voltage;
unsigned short int index;
};
Bal massifVoltageAndIndex[247];
public:
explicit SensorManager(QObject *parent = 0);
public slots:
void slotAutoModeBalancer(int numberBalanser);
};
#endif // SENSORMANAGER_H

При обращение

void SensorManager::slotAutoModeBalancer(int numberBalanser)
{
massifVoltageAndIndex.Voltage[0] = 1;
}

Получаю ошибку error: request for member ‘Voltage’ in ‘((SensorManager*)this)->SensorManager::massifVoltageAndIndex’, which is of non-class type ‘SensorManager::Bal [247]’ massifVoltageAndIndex.Voltage[0] = 1; Что не так ?