Solar panel neutral spike

Body

Staying at a friends who had PV solar installed.  When they were away
they came back and found a power strip melted that went to a treadmill
and a few of the ceiling fan controllers burned out.  Began to check the
circuit and found the ground wire from the Sunny Boy inverter cut at the
sheath inside the service panel.  The solar panels are about 100 yards
from the house and grounded to the concrete sunk racks, I really think
there should be a dedicated grounding rod also, but the grounding wire
inside the feed to the pair of breakers just cut not bonded to the
panel.  I am pretty sure this is against code besides being a hazard. 
Likely a lightening strike nearby pushed a nice big pulse through the
neutral wire and reflected off the inductive loads.

I am furious at this kind of stupidity but before I give hell to the
installer I want to make sure my thinking is correct.  Perhaps Dave can
give his two cents if for any reason the inverter should be floated like
this instead of bonded to the panel.

There seems to be a controversy on the topic:

https://www.solarpaneltalk.com/forum/solar-panels-for-home/solar-panel-system-equipment/16949-grounding-code-690-47-c-3-implementation-with-sma-sunnyboy-tl-us-22