Editor's Note: Scientific American's George Musser will be chronicling his experiences installing solar panels in Solar at Home (formerly 60-Second Solar). Read his introduction here and see all posts here.

Solar power involves wondrous quantum physics and materials science, but its fate may hinge on whether contractors can learn to bolt on the panels without losing too many screws. The panels themselves account for only about half the cost of a solar array; the rest is the installation and back-end equipment. As panel makers slash their prices, the nuts and bolts loom ever larger. Fortunately, a quiet revolution is now underway in installation. Brendan Neagle, the chief operations officer of Borrego Solar, a major U.S. installer, says they've sped up installation by 40 percent over the past two years. Zep Solar has invented a new roof mounting system, already supported by the module maker Canadian Solar, that speeds things up by another factor of two. And Nat Kreamer, president of Acro Energy, another large installer, says they've streamlined the preparation work and can get a system up on your roof within 30 days of your first phone call -- quite an improvement on the eight or so months it took me.

In fact, historically, most of the cost savings for solar power have come on the low-tech side. According to a Lawrence Berkeley Lab study last year, arrays in 1998 cost about $11 per watt of generating capacity: $5 for the modules themselves, $6 for the installation and equipment. By 2008 the modules have fallen by $1 per watt, the installation by $2. Prices have come down as installers have climbed up the learning curve. And there's clearly room for them to do even better. The study reported that arrays in Germany are $2 per watt cheaper than in the U.S. "Anything that is inefficient needs to be attacked," says Mike Miskovsky, the general manager of Canadian Solar.

Zep Solar CEO Jack West says he began to rethink mounting systems 12 years ago. The roof-mounted rack for a typical 5 kW array consists of 429 metal rails, screws, washers, and other parts that must be hauled up to the roof, kept organized so they don't go missing, and bolted together using a power drill and a set of nut drivers. The electrician must then run grounding wires to all the metal pieces for safety. Often the parts are a mix of copper, aluminum, and steel, creating dissimilar metal junctions that slowly corrode. In a few years, we may see a wave of grounding failures that create a risk of electrocution for anyone who touches an array.

The system he and his colleagues developed has 91 parts (see the comparison photo above, although it shows a 2 kW rather than 5 kW system) and requires just the drill and one specialized hand tool. The system has a minimalist elegance. A small, adjustable mounting bracket anchors each panel to the roof, and a lateral Erector-set-like piece connects adjacent panels, providing both mechanical support and a grounding connection. In the company's demonstration video, a pair of workers installed an array in 15 minutes, versus one hour for the standard array (not counting the set-up time on the ground). ZepSolar vice-president Daniel Flanigan claims that the system reduces labor and parts costs by about 50 cents per watt. It also makes it easier to remove and replace a panel should the need arise.

I should point out that I haven't verified these claims firsthand, although I can attest to the difficulty of assembling a conventional mounting frame. Neagle agrees that most mounting systems are baroque and says he likes the Zep approach, although he's waiting to see how it proves itself in practice.

Neagle told me about the myriad other ways Borrego has cut installation costs. They preassemble panels into units of four before arriving on the site, standardize practices such as which side of the array to run the wires on, and, adhering to the "measure twice, cut once" adage, thoroughly plan out the installation before anyone gets near a ladder. The company has a team of people who do Frederick Taylor-like controlled experiments of new techniques, using a stopwatch and timekeeping logs. They both collect ideas from workers and train and retrain them. Kreamer offered similar lessons and also says that cost-cutting generally means consolidating smaller firms into a larger company to spread out the overhead costs.

One challenge, says David Kaltsas, vice-president of SunWize, a large distributor of wholesale solar equipment as well as a residential installer on the West Coast, is a shortage of experienced and talented workers. And that's also a reason that solar arrays are, for the most part, not quite a DIY project yet. Putting them up take expertise and, if anything, the amount of expertise they take has been increasing. Over time, the efforts to simply the process for the professionals may filter down to us weekend warriors. For now, though, I think homeowners would be grateful simply for lower prices.

Photo courtesy of Zep Solar