Right now SAM only supports four types of utility rate units: kWh, kWh/kW, kWh daily, and kWh/kW daily. However, URDB supports additional rate units such as kVA and hp: https://openei.org/services/doc/rest/util_rates/?version=8

If the user attempts to download one of these rates, provide a notice that they may need to do the conversion themselves.

An example rate: https://openei.org/apps/IURDB/rate/view/539fbce2ec4f024c27d8756d#1__Basic_Information

A comment from Steve on a previous PR with more possible examples: NatLabRockies/ssc#580 (review)