Hi,
We have been involved for several years with solar water pumping systems used in developing countries to bring water to villages in remote off-grid areas. I've directly installed 3 systems in Nicaragua and 1 in the Philippines. In a few weeks, I will be helping a local Filipino non-profit repair 2 systems that they installed a few years ago.
Brands so far include: Sunpumps (AZ), Grundfos, Mono (Australia), and the 2 for repairs are Lorentz. ALMOST ALL OF THEM SO FAR have had electronics damage apparently due to lightning, even though most of the systems include lightning arrestors, either wired into a main breaker (Sunpumps), or built into the controller (Mono).
A system down means that the villagers (usually women and kids) have to spend several hours every day fetching water down the mountain for their basic domestic needs.
I read in a detailed technical note pulled from this Alt-E site (SAND 2005-0342 Printed February 2005), a recommendation to use two separate ground rods: one as a direct path to ground from the array metallic structure (post, frame, and panel frames ground lugs), and another rod to connect the equipment ground (controller, motor). A DC lightning arrestor would then be connected at the breaker, connected to +, -, and equipment ground.
Does anybody have any experience with this?
All the manufacturer's installation manuals I've seen show a single grounding rod, and usually the metal case of the controller is attached to the array post anyway, so I suspect that technically their ground terminal is somewhat bonded to the casing and the post and array ground.
Would it make sense to install the breaker and controller to some unique support/post unrelated to the array? Then to use the 2-rod approach?
I also plan to inspect ground lugs and electrical connections between the frames and the existing grounding rods.
Can anybody think of anything else I should be looking for and implementing from now on?
Thanks a lot.
Michel
