I see the large lights used for illumination at night, but they are shaped kind of like a round ball and powered with generators. Thank you.
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バルーン投光器. You can buy one for $800 store.shopping.yahoo.co.jp/buymaruichi/2016-12h51.html – broken laptop Mar 15 '17 at 20:39
I think most people who are not in the construction industry just call them ライト (or something like 工事現場のライト).
If you really need a specific term for that purpose, you can use 投光器【とうこうき】 or 作業灯【さぎょうとう】.