Wholesale electricity prices in Japan markets firmed up in the week ending October 9 as supply from photovoltaic (PV) power centers lessened under overcast skies. And weak supply from non-PV plants in west Japan widened the gap between low east and high west, an unordinary price structure. Based on the Rim Power Index (Day ahead 24 hours), weekday power prices in the eastern market, including Hokkaido, Tohoku and Tokyo area, averaged out at 4.62 yen per kilowatt hour (kWh), up 0.33 yen/kWh or 7.7 % from the previous week, meanwhile prices in the western, made up of the Chubu, Hokuriku, Kansai, Chugoku, Shikoku and Kyushu area, at 6.16 yen/kWh, up 1.30 yen/kWh or 26.7%.

Cloudy conditions crimped PV generation nationwide, tightening the balance of supply and demand for daytime. Additionally, in west Japan, non-PV plants, including a 870-megawatt nuclear reactor suspending for periodical checkups on Oct 7, seemed to power down, driving prices higher than east.

The premium of Hokkaido to Tokyo stood at minus 0.13 yen/kWh in the previous week, with Hokkaido's 24 hours average 4.52 yen/kWh (previous week's ave:4.29 yen) and Tokyo's 4.65 yen/kWh (4.29 yen), which are reckoned in conformity to data compiled by the Japan Electric Power Exchange (JEPX). Hokkaido prices often drift at higher levels than other areas especially in the winter season. But, weather conditions in Sapporo, the largest city in Hokkaido area, were better than Tokyo, appearing to provide a better supply from PV. Tohoku's central city, Sendai also saw more sunny spells, and Tohoku's 24 hours averaged out 4.52 yen/kWh, 0.13 yen/kWh lower than Tokyo.

Kansai's weekly average got higher to 6.22 yen/kWh from 4.70 yen/kWh, and Kyushu's rose to 5.93 yen/kWh from 4.70 yen/kWh. The difference of the two areas reoccurred, standing at 0.29 yen/kWh compared with zero observed in the previous week. Kansai area is the biggest market in the western Japan, and Kyushu's prices are incline to move at less expensive levels alongside of other areas.

On JEPX, the weekday average of System Price (Day ahead 24 hours), which were figured based on the data of 9 areas, gained by 0.83 yen/kWh or 19.2% to 5.15 yen/kWh, with the average volume decreasing by 16, 720 megawatts per hour (MWh) or 1.9% to 843,595 MWh compared to the prior week's.

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