[RE-wrenches] Designing PV systems for lightning prone areas

[North Texas Renewable Energy Inc]

James
It's hard to beat buried copper. At an array of 4-14 foot high trackers we
installed in 2005 we buried over 700 feet of bare copper in the same
trenches, a foot above the conduit runs. The ground was limestone so driven
rods were out of the question. There was also a Ufer ground to each 8 foot
pier.
The site received a direct lightning strike to a 24 ft weather station mast
only 100 feet from the nearest tracker. The arc jumped to a steel well
casing another 100 feet the opposite direction from the trackers.
I'm convinced the lightning never "saw" the trackers due to their low
impedance to earth. The steel casing didn't hurt either but the trackers
were a much bigger target.

Jim Duncan
North Texas Renewable Energy
NABCEP Certified Solar PV
Installer No.031310-57
TECL 27398
ntrei at 1scom.net
817.917.0527
www.ntrei.com


Dear Wrenches,

Does anybody have any best practices for designing large PV arrays on metal
building in lightning prone areas? Lightning arrestors on the DC side and
Surge suppressors on the AC load side? Any input or resources would be
greatly appreciated.

Sunny Regards,

James Rudolph
NABCEP Certified Installer
Master Electrician
SF Energy









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