Are Enphase inverters made in the US?

No, Enphase inverters are not made in the USA; but they are ARRA compliant.

Here is some info from the Enphase Energy website:

Enphase Microinverters received a waiver for the Buy American provisions (section 1605) of the ARRA, per a determination of inapplicability made by the office of Energy Efficiency and Renewable Energy at the U.S. Department of Energy. 

Please read the attached MoD from Department of Energy.

I'm also attaching other brands' ARRA compliance letters below.