The $400B Wiring Problem That Solar Can't Solve Alone

In 2009, a solar panel cost roughly $2.10 per watt. Today that number sits around $0.20. The learning curve did its job. Panels became commodities. Installers raced to the bottom on price. And the world celebrated because solar had finally beaten fossil fuels on cost.

But here's the part the celebration missed: the panel is only about 25% of the total installed cost of a utility-scale solar project. The rest goes to what the industry calls balance of system (BOS), the less glamorous collection of cables, combiners, inverters, wiring harnesses, fuses, disconnects, and monitoring hardware that actually turns sunlight into grid-ready electricity. While panel prices dropped 90% over the past 15 years, BOS costs have been far stickier. Labor is rising. Copper is expensive. And the projects themselves are getting bigger, more complex, and more demanding.

This creates a problem that very few people outside the solar construction world think about. When a utility-scale solar farm scales from 100 megawatts to 500 megawatts, the number of individual connections between modules doesn't just grow linearly. It compounds. More modules means more junction boxes, more homeruns (the long cable runs that carry power from strings of panels to the inverter), more combiners, and more points of potential failure. A 500-megawatt project might have over a million individual electrical connections. Each one is a place where resistance losses eat into output, where a bad crimp can cause an arc fault, where water intrusion can slowly corrode a contact until one day a string goes dark and the owner doesn't notice for months.

This is why the most sophisticated solar developers have started paying very close attention to what's called the electrical balance of system (EBOS), a subset of BOS that focuses specifically on the DC side of a solar plant. EBOS encompasses every wire, connector, combiner box, and monitoring device between the panel and the inverter. It's the circulatory system of a solar farm. And for years, it was assembled on-site by electricians pulling cable through conduit, hand-crimping lugs, and wiring combiner boxes one terminal at a time.

The inefficiency was staggering. A 2023 study by the National Renewable Energy Laboratory found that electrical installation accounted for roughly 30% of total labor hours on a utility-scale solar project. On a large site, that could mean hundreds of electricians working for months, making tens of thousands of individual connections in the dirt. Every connection made in the field was a quality control gamble.

Then someone had a better idea: what if you built the entire DC electrical system in a factory?

The concept is called a Big Lead Assembly, or BLA. Instead of running individual wires from each panel string to a combiner box and then from the combiner to the inverter, you pre-fabricate the entire wiring harness as a single plug-and-play unit. The cables come pre-cut to length, pre-terminated with weatherproof connectors, pre-tested for continuity and insulation resistance. You ship it to the site on a spool. The installer unrolls it, plugs it in, and moves on. No crimping. No conduit. No guesswork.

The labor savings are dramatic (40-60% reduction in electrical installation time by most estimates), but the real value is in reliability. A factory-made connection tested under controlled conditions is categorically more dependable than a field-made connection assembled by a crew working in 100-degree heat on a deadline. Over the 30-year life of a solar plant, those quality differences compound into meaningful differences in energy production and maintenance cost.

This shift from field-built to factory-built EBOS is one of the most important trends in solar construction, and it's still early. The majority of utility-scale projects worldwide are still wired the old way, by hand, on site. But the transition is accelerating as project sizes grow, labor gets more expensive, and developers realize that the cheapest panel in the world is worthless if it's connected by bad wiring.

The company that essentially invented this category, the one that holds the patents on the BLA concept and has shipped EBOS for over 60 gigawatts of solar capacity, started not as a solar company at all. It began in 1996 as a small electrical components shop in Tennessee, making wire harnesses for industrial equipment. Its founder, Dean Solon, was an electrician by trade who got tired of watching crews waste time and make mistakes doing repetitive wiring work that could be standardized. He figured there had to be a better way. Three decades later, his company sits at the center of the solar industry's most important supply chain shift.