This chapter has revealed the necessity for developing grid standards in integrating RPPs into existing transmission networks. A variety of technical issues such as reactive and real power control, voltage and frequency ride through, and frequency and inertial response have been found to be addressed in the existing international grid codes. However, these regulations are subject to continuous changes. HVRT and reactive power support during the fault period are two major additions in grid codes over the last few years. The authors believe that the comprehensive comparison of principal grid codes presented in this chapter would be beneficial for network operators as well as for manufacturers of RPPs. This study would help new TSOs to develop their requirements and compare them with the requirements set by the TSOs in countries with a large share of renewable power. However, it is worth mentioning that each TSO should develop its own grid codes depending on the availability of renewable resources in the region, strength of existing network, and local utility practices.