Why don't we connect the direct DC power that we get from the solar photo-voltaic to the HVDC transmission?

Connecting direct DC power from solar photovoltaic (PV) systems directly to High-Voltage Direct Current (HVDC) transmission lines is not straightforward due to several reasons:

1. Voltage Levels: Solar panels typically produce low-voltage DC power, which needs to be stepped up to match the high-voltage levels required for HVDC transmission. HVDC systems operate at much higher voltages, often in the range of hundreds of kilovolts, to minimize transmission losses over long distances12.

2. Power Conversion Efficiency: While solar panels generate DC power, the output voltage and current need to be adjusted and stabilized to match the requirements of the HVDC system. This often involves using DC-DC converters or other power conditioning equipment to optimize the energy transfer5.

3. Maximum Power Point Tracking (MPPT): To maximize energy output from solar panels, MPPT controllers are used. These controllers adjust the operating point of the solar panels to extract maximum power, which is crucial for efficient energy production. Direct connection to HVDC might not allow for optimal MPPT tracking without additional conversion stages14.

4. Grid Integration and Stability: HVDC systems are designed to handle large-scale power transmission and often require sophisticated control systems to ensure grid stability and synchronization with AC grids. Directly connecting solar PV systems to HVDC without proper conditioning and control could compromise grid stability1.

5. Safety and Reliability: High-voltage DC transmission requires specific safety measures and equipment to handle the high voltages and currents involved. Direct connection of solar PV systems would need to meet these stringent safety standards to prevent accidents and ensure reliable operation2.

In summary, while it is technically possible to connect solar PV systems to HVDC transmission, it requires additional power conversion and conditioning steps to ensure compatibility, efficiency, and safety. These steps include voltage adjustment, MPPT tracking, and integration with sophisticated control systems to maintain grid stability and reliability.