Home Sizing the System The Structure The PV panels Field Wiring Tilt Angle

Field Wiring


AC Wiring

The AC system wiring was pretty straightforward, so I tackled it first. Since it involved four inverters, I elected to use four 15-amp two-pole circuit breakers in a sub panel to combine their outputs into a single pair of conductors that travel via disconnects and private meter to the main utility panel. I included the private kWh meter to monitor system performance.

The system is a 120-ft walk from the main utility panel, so there is a local disconnect next to the sub panel. The signage, required per NEC, was designed to SDG&E specifications and was laser-engraved at a local trophy shop.


I used #8 THWN building wire for the individual inverter circuits, and #4 THWN from the sub panel bus bar through the disconnects and meter and on to the main panel. All of these conductors are housed in schedule 40 sunlight-resistant PVC conduit. The planks form a catwalk for inspecting and cleaning the PV surfaces (bird problems mostly).


Here the system ties into the utility panel. Wiring from the disconnect to the panel is in the wall. The circuit terminates in the main panel at a two-pole 40-Amp breaker. The paint on the main panel had started peeling, so I scraped it off before affixing the signage. I'll repaint sometime this summer when I paint all the above-ground PVC conduit.


DC Wiring

The DC field wiring presented a few challenges,  beginning with selection of an appropriate type of wire. The PV panel wiring is exposed, but the conductors are gathered into PVC conduit runs for protected delivery to the inverters.


I accomplished the transition to conduit with PVC LB conduit bodies, drilled and fitted with elastomeric squeeze bushings similar to those included with the Kyocera panels.


Inverters 1, 2, and 3 each serve a cluster of five PV bays (strings) and are physically located a few feet north of their respective center bays. Inverter 4 serves a partial cluster of three bays with capacity for future expansion to two more  bays. DC conductors to each inverter are housed in two 1-1/4" conduit branches.

Here's a helpful hint. If pulling a bundle of wires through conduit takes more effort than you'd like, wipe each of them lightly with Armorall as they enter the conduit. It works much better than the "snot" they sell at the electrical supply house.


At last it was time to call for inspection, then sit back to enjoy the view.