Q. See question 4391 regarding blowing shofar during Elul when there is no minyan.
Horav Kalman Ochs Shlit’a commented that since some Poskim maintain that the shofar applies during Elul even without a minyan present (see Siach Yitxchok 264). And since the blowing is done with the purpose of awakening people to do Teshuva, it is worth to do so.
Rabbi A. Bartfeld as revised by, Horav Dovid Pam, Horav Aharon Miller, Horav Chanoch Ehrentreu and Horav Kalman Ochs Shlit'a