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Hitachi has put together a package of products with top priority given to annual power generation.
Photovoltaic power generation operates under rapidly changing weather and other conditions. As only a few days a year will have the right conditions for maximum power generation, a key consideration is how to increase total annual power generation efficiently so that electric power can be sold back to the grid. It was to meet this challenge that Hitachi came up with this package for photovoltaic power generation systems featuring equipment selected on professional criteria. The benefits of using the package extend beyond just simplifying the process of equipment selection, they also include highly efficient operation and low standby power when not generating.
As light levels can change rapidly, the power output from the PV modules varies widely. This means that the PCS must be able to cope with a wide range of DC input voltages. The PCS can efficiently convert DC voltages between 230V and 600V into AC.
The high 98% conversion efficiency increases the power output. For example, a 1% improvement in system efficiency increases the photovoltaic power generation system's annual power generation by 13.7MWh or 27.3MWh.
Because photovoltaic power generation does not work at night, reducing no load losses is important. Compared to Hitachi’s electrical steel transformers, the amorphous transformer reduces standby power when not generating by 73%.
Because the low-voltage AC power input to the transformer varies widely, it is important that it be converted efficiently to high-voltage AC power for connection to the grid. The low transformer losses mean higher conversion efficiency and increased power output.
A service is provided for realtime measurement and monitoring of the photovoltaic power generation system.
When different combinations of PV module output and PCS output are compared, it is found that annual power generation is maximized by combining a 1.3MW PV module with a 1.0MW PCS.
This means that power generation must be efficient. The PCS only operates efficiently above a certain load. Using a PCS with an output lower than the PV module increases annual power generation by allowing it to operate in a higher efficiency range.