I've been using an active directory account with domain admin rights to perform SolarWinds functions. Does this account need domain admin rights, or can I use lower privileges?
Depends on what you mean by "solarwinds functions".
If you mean "the account used for polling servers with wmi", yes that is the easiest but not required. That account need to be local admin on all polled server, domain admin is.
Otherwise, please tell us more what you want the account to do.