Wind and solar energy production is intermittent and variable, causing voltage fluctuations in the power system. These fluctuations can affect supply and demand balance, leading to voltage instability. In some cases, integrating solar and wind energy can result in overvoltage or undervoltage conditions, which can negatively impact the power grid's operation. The research examines the effects and challenges of integrating wind and solar energy into power grids, concentrating in particular on issues with voltage stability. The investigation explores fundamental issues like voltage stability-based distributed power generation (DG) unit sizing and optimal locations, stability of voltage assessment and methods for enhancement. Experiments are conducted to examine the effects of energy storage devices, adaptive alternate current (AC) transmission lines, static caps and other electric components of the system on the stability of the voltage of the distribution and transmission networks. It provides a comprehensive examination of the technical difficulties, such as the stability issues associated with incorporating massive solar systems into the electrical grid. The research obtained results on technical methods to address the power instability challenges with the integration of solar power on a massive scale into the transmission system and its subtransmissions, known as the medium voltage distribution system.