Photovoltaic inverter works at night

Photovoltaic (PV) inverters are vital components for future smart grids. Although the popularity of PV-generator installations is high, their effective performance remains low. Certain inverters are designed to operate in volt-ampere reactive (VAR) mode during the night.

One solar power inverter that exemplifies the benefits of the Q at Night function is Sungrow's 6.25/6.8 MVA MV Turnkey Station. Here's what makes this inverter system a standout choice for large-scale solar applications:

For photovoltaic (PV) inverters, solar energy must be there to generate active power. Otherwise, the inverter will remain idle during the night. The idle behaviour reduces the efficiency of the PV inverter. However, if there is a mechanism to use such inverters in a different way at night, its efficiency can be increased.

Retaining the active power at zero in Fig. 8b indicates that the inverter has the ability to inject pure reactive power without consuming active power from the grid. Finally, the results validated that this inverter model can be used during the night as a pure reactive power generator without consuming any active power from the grid.

The PV inverters theoretically can be developed as reactive power supporters, the same as the static compensators (STATCOMs) that the industrial standards do not address . Typical PV inverters are designed to be disconnected at night. Alternatively, it is possible to use its reactive power capability when there is no active power generation.

In addition, the needs of additional generators can also be addressed by providing extra reactive power, offering an additional source of income. In order for the PV system to also be able to feed in reactive power at night, the inverter must be fitted with the "Q at Night" option.