This works for me:
gdbus call --system --dest net.hadess.PowerProfiles --object-path /net/hadess/PowerProfiles --method org.freedesktop.DBus.Properties.Set 'net.hadess.PowerProfiles' 'ActiveProfile' "<'power-saver'>"
sleep 0.1
gdbus call --system --dest net.hadess.PowerProfiles --object-path /net/hadess/PowerProfiles --method org.freedesktop.DBus.Properties.Set 'net.hadess.PowerProfiles' 'ActiveProfile' "<'balanced'>"