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Hitachi

Photovoltaic Power Generation System

About Component Package

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.

  • Highly efficient equipment selected based on Hitachi’s considerable experience with building photovoltaic power generation systems.
  • Key equipment required for a photovoltaic power generation system, together with associated documentation. This helps speed up engineering, procurement, and construction planning work.
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The package does not include site preparation and electrical installation. Refer to the Customer Responsibilities section for more information.

PV module

  • Two product offerings to suit different levels of annual power generation
  • PV module output : 1.3MW or 2.6MW
  • Equipment supplied by Hitachi:No.7, 8

Image : PV module

PCS (Power Conditioning Systems)

  • Boosts power generation by achieving high efficiency across a wide range of voltages
  • PCS output : 1.0MW or 2.0MW
  • 98% maximum efficiency
  • Equipment supplied by Hitachi:No.6

Image : PCS

Feature 1 : Supports a wide range of DC voltages

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.

Feature 2 : Higher efficiency means higher power output

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.

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Depends on location and conditions at installation site.

Amorphous transformer

  • A smart approach to power sales with low standby power when not generating
  • 73% reduction of standby power when not generating
  • Equipment supplied by Hitachi:No.5

Image : Amorphous transformer

Feature 1 : Low standby power when not generating

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%.

Feature 2 : Higher conversion efficiency increases power output

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.

Switchgear

  • This acts as the point of interconnection between the photovoltaic power generation system and the electric utility’s grid.
  • Equipment supplied by Hitachi:No.1, 2, 3

Image : Switchgear

Monitoring system

A service is provided for realtime measurement and monitoring of the photovoltaic power generation system.

Why do you provide a PCS with a lower output than the output of the PV modules?

Unusual correlation between PV module output and PCS output

Annual power generation for different combinations of PV module output and PCS output

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.

Over the course of an entire year, high light levels are only present for a short time

PCS efficiency curve

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.

That is, when year-round light levels and PCS efficiency are considered, the optimum combination is a PV module with an output of 1.3MW and a PCS with a net output of 1.0MW.