I don't think solarwinds supports L2 netflow with nexus yet. Assuming it doesn't work for 7k it also doesn't work for 6k.Netflow for Nexus 7000
Updated August 24, 2016
This is an overview of what the configuration would look like on a Nexus 7000.
All NTA versions
Netflow can only be enabled for VLAN because it will allow Layer 3. The interfaces will only do Layer 2 and NTA does not support Layer 2 at this time.
flow exporter FLOW_NAME
destination <Solarwinds Sever IP> use-vrf management
transport udp 2055
template data timeout 90
flow monitor FLOW_NAME
See also Netflow 7000 for more information.