Used this last year and it worked well on composite.
https://www.amazon.com/DeckMAX-Concentrated-Composite-Wood-Cleaner/dp/B085P25DX7?pd_rd_w=PRrqG&content-id=amzn1.sym.b854a5c2-4475-41f8-a6d4-df92b2868104&pf_rd_p=b854a5c2-4475-41f8-a6d4-df92b2868104&pf_rd_r=CS16JFP5VMMXR28C16YB&pd_rd_wg=kWVLk&pd_rd_r=2cca0887-c232-430e-980d-a8e095b7ff33&pd_rd_i=B085P25DX7&psc=1&ref_=pd_basp_bia_rpt_ba_s_2_sc