Journal of Japan Solar Energy Society
Online ISSN : 2433-5592
Print ISSN : 0388-9564
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Research paper
  • Hiroki TAKEGATA, Ryo NISHIMURA
    2020 Volume 46 Issue 5 Pages 57-62
    Published: September 30, 2020
    Released: October 06, 2020
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    Arid land is desirable place for PV power generation because of fine weather. However, sand accumulation on PV modules decrease the generated power in such area. It is not appropriate using water to remove the sand in arid land. Electric field curtain (EFC) is one of a promising method to remove the sand without using water. In this paper, we report on the sand removal characteristics of three-phase EFC for various voltage, electrode distance, tilt angle and cover glass thickness, which corresponds to cover glass of PV module, of EFC. It is shown that high EFC voltage, large tilt angle, thin cover glass and narrow electrode distance give good sand removal characteristics.

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  • Ren ISHIKAWA, Hironobu MATSUO
    2020 Volume 46 Issue 5 Pages 63-70
    Published: September 30, 2020
    Released: October 06, 2020
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    To evaluate the economy of installing a storage battery system to a post-FIT photovoltaic power system for residential use, we conducted a power transmission simulation and calculated the annual economic effect in Hamamatsu, Japan. The simulation was performed using the battery capacity, connection method, charge/discharge control method, and working time of heat pump water heater (HPWH) as parameters. As a result, it was found that the initial cost of the battery system cannot be recovered under any conditions. The initial cost can be recovered if the cost drops to 35% of the current level, the battery life reaches 28 years, or the power price increases to 186% of the current level. By shifting the working time of HPWH to daytime without installing a battery system, it is possible to reduce 3700 yen annually, which is effective for homes that have installed more than 5 kW PV system with relatively high irradiation areas.

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  • -Method for temperature control of shaded cells-
    Koki UEDA, Sanshiro YAMANAKA, Yasuhiro AOYAMA, Yuki NISHIDO, Hiroshi K ...
    2020 Volume 46 Issue 5 Pages 71-78
    Published: September 30, 2020
    Released: October 06, 2020
    JOURNALS RESTRICTED ACCESS

    An open failure of the bypass diode (BPD) of a photovoltaic module can damage the cell. With existing inspection methods, it is difficult to find an open failure of a BPD. A method for finding open failure of BPDs using thermal imaging was investigated. The following points were clarified in this study. In a partially shaded cell, the unshaded portion of the cell generates heat. There are two types of heating: surface heating and point heating. They occur simultaneously. Point heating causes the back sheet to burn. However, if the shaded area is 10%, the cell does not burn as a result of point heating for a long time. Surface heating can cause the heat generation temperature of the cell surface to become high. The heat generation temperature can be adjusted by setting the number of shaded cells so that multiple cells are shaded. The heat generation temperature of a partially shaded cell differs depending on whether the BPD is open.

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  • Masaya IKUKAWA, Ryo NISHIMURA
    2020 Volume 46 Issue 5 Pages 79-85
    Published: September 30, 2020
    Released: October 06, 2020
    JOURNALS RESTRICTED ACCESS

    PV power plants installed in arid lands can generate large amounts of power because of fine weather. However, sand accumulation on PV modules decreases the generated power in such area. It is not desirable using water to remove the sand in arid land. Electric field curtain (EFC) is one of a promising method to remove the sand without using water. If EFC is adopted to PV modules, high-voltage conductor is placed very near the PV cells. In this paper we report on the effects of high voltage conductors placed on the PV module surface on the power generation characteristics. It is shown that high voltage stress at high temperature may degrade the power generation performance.

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