A friend of mine called with questions about overcurrent
protection for direct current (DC) output of photovoltaic (PV)
modules, the DC output of combiner boxes, the location of
disconnects for both DC side and the alternating current (AC)
side of an inverter, and sizing conductors on both sides. My
friend is very knowledgeable about the National Electrical Code
(NEC), was an electrical inspector for many years, and now
teaches the NEC and PV installations. As I explained the
requirements and provided the answers with references within the
NEC, I realized our discussion and the information was important
for anyone working on PV systems. PV modules are listed as an
assembly of solar cells, optics, a connection box and DC output
leads, which are typically assembled within an aluminum frame
with specific mounting and grounding means, such as bolts,
mounting clamps or grounding clamps. The solar cells within the
module are connected in series or are parallel combinations of
cells connected in series. Based on Ohm