Reports are somewhat varied here but we find that about 10-20% of the overall site cost goes into labor. The bulk of the rest is component cost for solar modules and tracking systems, which are relatively commoditized and so are a thin margin above the cost of the raw materials to make them (silicon, steel). Those costs won't drop unless the underlying materials get cheaper.

We find that beyond the direct cost, the logistics of getting hundreds of people to a remote site is a significant challenge for construction companies. We directly saw how much of a hurdle this can be when we were on a site with the closest city an hour and a half away. Weather conditions are also a factor here, work on the site was actually shut down due to conditions that were too cold for laborers.

As we've interviewed solar construction companies, all of them have told us that they're turning down potential jobs just because they don't have enough people/capacity to build them. Unfortunately they can't simply raise their hourly rate by a few dollars to make this problem go away, because the challenges are more the regional specificity and logistical challenges of getting workers to sites.

I am a little surprised that silicon is still competitive. I had the impression that cadmium telluride was much cheaper, in bulk. Or is it about reliability/lifetime?

(For home use, I worry about my neighborhood becoming a superfund site in event of a fire. I read claims that fire burning the house under CdTe panels will not release the 8g/m^2 of cadmium on them, but don't know how to evaluate that.)

Yes, silicon is still the majority[1], and it really just boils down to all-in cost. In watts per dollar thin-film ends up being reasonably competitive with silicon, but only because it's manufactured in the US which has steep import tariffs on foreign PV modules.

[1]https://www.usa-cdte.org/

Ah, thanks, I missed the tariff bit.

Is the solution than perhaps the rapid build up and turn down of mini cities for workers during the build phase? The problem sounds like Black Rock City public works for solar projects, versus robots for labor needs that can change rapidly (trenching, racking install, panel mounting, etc).

TLDR Worker housing and logistics vs robotics.

Black Rock City's DPW for solar is a really interesting idea! Temporary housing is definitely used at times for more remote projects, but it's more expensive than just booking out all the local hotels (of course, once you've saturated hotel rooms you might not have the option).

Fortunately the labor needs are typically predictable, with each step you mentioned happening in parallel across a site spanning 100's or 1000's of acres. One of the main reasons that larger sites are particularly appealing for us is that the work done by our robots is continuously in demand somewhere, as opposed to a small site which might move in more discrete stages and have the rapidly changing needs you mentioned.

I'm more interested in what kind of possibilities this unlocks. Sure, labor might not be a huge cost in projects at present moment. But that might be because all projects today are happening in places where labor is cheap. What if this unlocks projects in more remote and harsher terrains?

We joke that Mars will be the easiest market for us to penetrate :)

Not really from what I’ve seen. There’s a rabbit hole of research reports, but the key chart is shown here: https://www.solarreviews.com/blog/what-is-a-solar-farm-do-i-...

Maybe 10-15% of total cost depending on install type.

This is the real question

From my experience the biggest cost other than Panels and copper wire is the framing and structural infrastructure. Building codes, wind loads, etc. make it so its not as simple as propping up a few panels and plugging them in. It's significant and also cost inefficient in many ways.