Does my employer have the right to send me home?
The employer can send you home if he has the impression that you are sick or due to an infection, that presents a risk for your colleagues. The employer can also send you home as a precautionary measure. In both cases, your employer must continue to pay your wages. If you are healthy and able to work, the employer needs a good reason or your consent to send you home. If he has no good reason, you have the right to continue receiving your full wages.
If the employer does not have enough work for you he is not allowed to single handedly decide that you have to reduce your accumulated overtime hours, take vacation, or reduce the credit on your working time account. You can read what a working time account is here.