I'm a little rusty on making 110/120V systems work for gear like the S9's or Avalon 841's. They both have the ability or firmware to be underclocked to work but it's a stress on the system. Here is a thread from a while back that goes over the considerations, and has links to how people have made it work. https://bitcointalk.org/index.php?topic=2799754.0
Personally though I suggest you put in 220/240 V circuits for your miners. It's not difficult and would be offset by the cost of an additional PSU. Considering you said your power cost is low and not based on consumption, you can get a more powerful machine that is less efficient - which will help your earnings.

I linked another thread to review as I'm not sure where you are planning to place this machine but there are plenty of factors to consider before investing in gear. Good luck.

Topics for you to review:
First time/Small miner reference for getting started.
Current List of Competitive Hardware - July 2019

https://bitcointalk.org/index.php?topic=2799754.0