Here we explain the basics of a Solar Power Generation System, from the initial installation through to routine maintenance.

Equipment and System Components

  • What are PV cells, modules, and arrays?
  • What is conversion efficiency?

Equipment and Installation

  • What is the ideal roof gradient?
  • Are only roofs with a southern exposure suitable for installation of PV arrays?

Care and Maintenance

  • What is the durability and service life of a typical system?

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Equipment and System Components

Q What are PV cells, modules, and arrays?
A Cell: The basic unit of a PV system is the cell. First a silicon crystal is grown into a bar shape called an ingot. This is then cut into thin slices and electrodes are attached to create the cells.Module: A module is a package in which a set of cells are arranged in rows and covered with sturdy glass so that they can be mounted on a roof.Array: An array consists of multiple modules (panels) arranged either in series or in parallel and mounted on a frame.
Q What is conversion efficiency?
A The conversion efficiency expresses the percentage of light energy from the sun that is actually converted into electricity.The following formula can be used to calculate the conversion efficiency of a PV module.*

Calculation using exterior dimensions with protrusions omitted.

Equipment and Installation

Q What is the ideal roof gradient?
A The ideal PV panel angle from the standpoint of volume of electricity generated is 30 degrees in Japan. Though there are regional variations when installation and maintenance are taken into account, there should be no problem if the roof gradient is between 20 and 40 degrees. This amount of variation from the ideal will only result in a difference of about 2% in the amount of electricity produced.
Q Are only roofs with a southern exposure suitable for installation of PV arrays?
A Which direction does your roof face? The amount of electricity produced differs depending on the orientation of the roof. Make sure to confirm the orientation of your roof before installing PV panels. Note that it is also possible to combine panels oriented east and west, for example, in the same system.

Care and Maintenance

Q What is the durability and service life of a typical system?
A Service life: Typically, PV modules have a service life exceeding 20 years. The other equipment used in the system employs parts with a design service life of about 10 years.