As a solar-electric installer, I had my reservations about using a system that was such a departure from what I knew, but Claire was persistent—and I eventually agreed. At the time, 180 W was the biggest module Lumos Solar offered with a black back-sheet. The company I work for was installing mostly 235 W modules and 180s seemed a little behind the times. However, we had plentiful roof space, so power density was not a huge concern.
I settled on six strings of nine modules each, which required a fair bit of wire management. But the Lumos LSX rails have a spacious channel that accommodates everything nicely. I brought all the home-runs into an OutBack combiner mounted to the fascia on the north side of the roof, through a 60 A Eaton DC disconnect, and down to the power wall. That kept the south roof—with that amazing-looking frameless array—uncluttered.
The Lumos LSX modules and racks are an integrated system. Through four mounting holes, the modules are attached by bolts onto nuts constrained in the proprietary racks. It takes some getting used to—more time is spent perfecting the layout than with traditional systems, but there is a payoff—once racks and mounting nuts are all tuned, mounting the modules is very quick. I was nervous about the modules staying put as I worked, but the rubber strips on the rails eliminated sliding. The frameless modules are heavy, and no frame means no edge to grip. But it also means no metal parts to bond. In a 54-module system, that’s a significant time-saver, not to mention fewer potential points of failure. I used bonding jumpers at the rail splice locations and tinned #6 solid from rail to rail. The tinned wire is extra protection against dissimilar material interaction over the metal roofing.
Although I spent a frustrating couple of hours getting to know the system, we quickly learned to get along famously. I racked most of the 54 modules unassisted in just over a day. I can’t imagine doing that with traditional modules and rails.
Wire management channels in the rails (above) keep wires neatly organized and protected (below).