A reflection unit 31 to 34 has an outer reflection panel 311 to 314 and an inner reflection panel 321 to 324. The outer reflection panel 311 to 314 is disposed around power generation units 22 to 24. The inner reflection panel 321 to 324 is disposed substantively parallel to the outer reflection panel 311 to 314 between the outer reflection panel 311 to 314 and the power generation units 22 to 24. The reflection units 31 to 34 reflects solar light injected into gaps 361 to 364 between the outer reflection panels 311 to 314 and the inner reflection panels 321 to 324 to transmit the solar light into the power generation units 22 to 24.