The future of solar doesn't track the sun • Hacker News Board

Re: The future of solar doesn't track the sun

#51

Post by tzs » Sat, May 03, 2025, 3:42 PM UTC

I wonder if you could make a DMD [1] where instead of mirrors the tilting part is tiny solar panels?

The panels would only have two positions, but you could install half the DMD devices so that the two positions are south and southeast, and half so they are south and southwest. You could then have half your panels southeast and half south in the morning, all of them south midday, and have southwest and half south afternoon.

That would get you at least some tracking and it should be mechanically a lot more reliable than the systems that move large panels.

DMDs were designed for use in video projects, where they have to move the mirrors more times in 4 hours of video than a solar array would need to move the panels in 1000 years.

[1] https://en.wikipedia.org/wiki/Digital_micromirror_device

Re: The future of solar doesn't track the sun

#52

Post by Veserv » Sat, May 03, 2025, 4:39 PM UTC

jillesvangurp wrote: post #14

rini17 wrote: post #2

When panels are cheap what about vertical mounting? Less susceptible to hail and snow. And maybe placed north-south, to maximize production in morning and evening when it's needed most.

The article seems to be mostly about grid scale solar. Of course an increasing amount is private or domestic solar installed on e.g. building roofs or wherever there is space. When cost drops low enough, any surface with any exposure to sunlight is in scope for installing solar on if it can yield more energy than the cost of installing solar on it. It stops being about what is the most efficient and starts being abou…

Domestic solar is a rapidly decreasing fraction of total solar deployments [1]. Not because it is not growing exponentially, but because grid-scale is much more exponential with no signs of that changing.

[1] https://news.ycombinator.com/item?id=42591918

Re: The future of solar doesn't track the sun

#53

Post by hinkley » Sat, May 03, 2025, 6:39 PM UTC

tgsovlerkhgsel wrote: post #19

Looking at the graphs, the tracking arrays may have the added benefit of generating power in the mornings and evenings. If everyone builds non-tracking arrays, power during peak will become almost worthless if solar is a big part of overall generation capacity, so the economics might change even with panels being cheap. Of course, just building 2x as many permanently tilted panels might also work. Edit: the article a…

This is one of the areas where double sided panels reportedly win out. You can orient them to morning/evening light and they shed heat by convection better. Hot cells produce less electricity, which is why it’s difficult to construct Maxwell’s Demon from eg infrared-sensitized photovoltaics and band gapped radiators.

Re: The future of solar doesn't track the sun

#54

Post by hinkley » Sat, May 03, 2025, 6:43 PM UTC

ericd wrote: post #42

yummypaint wrote: post #32

Earlier quoted context omitted.

Demand isn't fixed in time either, though. Industrial processes that presently run at night to use cheap power will switch to daytime when it makes sense to do so. Summer mid-day also has the highest electricity demand all year in many places due to air conditioning, so arguably solar is addressing one of the biggest stress points.

Not an expert, but my understanding is that the challenge there is that a big cost in industrial production is the initial capital outlay for the equipment, and oftentimes to pay that back reasonably, you need to run the equipment nonstop. Also, some processes are challenging to stop/start.

This has been my understanding as well. But on the plus side, while you may run a machine all day, the price of cooling your equipment varies with the outside temperature and that is highly correlated with available renewable power. The AC units and diesel backup power are systems you buy and prefer to have idle. But not your press or data center.

Re: The future of solar doesn't track the sun

#55

Post by nbadg » Sat, May 03, 2025, 6:46 PM UTC

quesera wrote: post #29

dylan604 wrote: post #22

Earlier quoted context omitted.

anti-hail netting? you must not be from somewhere that receives a lot of hail. hail punches through solid coverings at the right size. if it's not the right size, then it's not that damaging. netting? ha! thanks for the funny visual so early in the morning.

I think a hail net would be feasible for some cases. Golf balls break solid coverings too (and windows, car roofs, etc), but we have nets for them. You want high tensile strength and some level of flexibility/elasticity to absorb the hailstone energy over a greater-than-zero distance. Or to shatter the hailstone well above the solar panel. Probably too light-blocking to leave up continuously, and maybe awkward and fa…

I agree with your implicit point that the key question is probably cost effectiveness compared with insurance. However, in the context of the OP, insurance premiums in hail-prone regions was listed as a prime reason why single-axis-tracking panel installations are, in some regions, probably still a better bet at grid scale.

The point I'm trying to make is just that there are a lot of off-the-shelf (or nearly so) hail protection strategies that seem like they might have better economics than single-axis-tracking installations, which might improve the cost effectiveness of a fixed panel installation to the point where, even in hail-prone regions, it might be doable.

To be clear: anti-hail nets are already a COTS product, just not for this application (as far as I'm aware). Nets are just really, really good at absorbing kinetic energy. I mean, that's effectively what kevlar ("bulletproof") vests are made of -- netting with a very small cell size. But it seems to me like some kind of roll-out kevlar or dyneema netting could be really effective at protecting panels, though I think you'd need some kind of better strategy for safely dispersing the hailstones after they were caught, so you don't end up with a huge collection of hailstones on the net.

I agree that there's probably too much light blocking to leave them up continuously, and I'd also be worried about UV damage. But remember that the comparison here is to single-axis-tracking installations; I think automatic deployment of anti-hail netting could easily be made at least as reliable as the tracking system, if not significantly more so. Maintenance and testing would also be very cheap in comparison, since you could do it at night (ie without affecting power production), and damage to the protection system could be repaired without taking panels offline.

The more I think about it, the more I'd be interested in seeing it deployed.

Re: The future of solar doesn't track the sun

#56

Post by mchannon » Sat, May 03, 2025, 6:47 PM UTC

I've been in solar energy as my primary vocation since the 1990's.

I've built solar cars, I've built solar panels, I've installed solar panels, I've designed solar trackers. I know this industry inside and out.

I'd never heard of an east-west array before (though I did experiment with one-cell-wide "crinolations" at 60 degree angles, did not find any value to using them but it was a different application where low-angle light wasn't a factor). I'd never thought of such an array on this scale, at this low angle, before.

I don't think most of the people reading this article quite understand that this is a completely different kind of array topology to flat-plate fixed-tilt, or tracking-based systems. Do yourself a favor, if you consider yourself intellectually curious, and if you came away from skimming this article thinking there's nothing new under the sun, read it again with a keener eye toward the novelty of it.

Re: The future of solar doesn't track the sun

#57

Post by WillPostForFood » Sat, May 03, 2025, 6:48 PM UTC

yummypaint wrote: post #32

leoedin wrote: post #27

Earlier quoted context omitted.

Yeah - you can’t talk about renewable energy generation without also considering when it is generated. Then future price of energy will be incredibly time dependent. Finding a way to generate at a different time than everyone else - whether by east/west panels or time shifting with batteries or building a different kind of renewable generation is where all the big profits will be.

Demand isn't fixed in time either, though. Industrial processes that presently run at night to use cheap power will switch to daytime when it makes sense to do so. Summer mid-day also has the highest electricity demand all year in many places due to air conditioning, so arguably solar is addressing one of the biggest stress points.

"summer mid-day also has the highest electricity demand all year in many places due to air conditioning,"

Peak electric demand is 3-7pm in the summer. You might think you could then just set panels to to optimize for afternoon, but especially in winter, you get a big peak between 6-9am.

Re: The future of solar doesn't track the sun

#58

Post by [deleted] » Sat, May 03, 2025, 6:53 PM UTC

[deleted]

Re: The future of solar doesn't track the sun

#59

Post by bob1029 » Sat, May 03, 2025, 6:55 PM UTC

tzs wrote: post #51

I wonder if you could make a DMD [1] where instead of mirrors the tilting part is tiny solar panels? The panels would only have two positions, but you could install half the DMD devices so that the two positions are south and southeast, and half so they are south and southwest. You could then have half your panels southeast and half south in the morning, all of them south midday, and have southwest and half south aft…

A DMD is a really good thought, but I don't know if the surface area would work out at scale.

I think the power handling limit of typical devices is something like 100W/cm^2.

The UV from the sun would also degrade these devices faster.

Re: The future of solar doesn't track the sun

#60

Post by nbadg » Sat, May 03, 2025, 6:57 PM UTC

dylan604 wrote: post #38

medoc wrote: post #33

Earlier quoted context omitted.

Anti-hail netting is definitely a thing (protecting cars or fruit trees), for the reasons you state. Even big hailstones are rather slower than fast golf balls.

Hail damage at car dealerships in my area is so expensive that the dealers have added coverings for the lots (pretty sure highly encouraged by the insurance companies), and they are most definitely not nets. Nets would have been cheaper, so that should say something about their effectiveness (or not)

Hail protection nets are a COTS product. Full stop. Properly-designed nets are exceptionally strong; that's why we make "bulletproof" vests out of them (that's all they are, just a fiber net with a very tight weave).

Just because your local car dealership(s) didn't opt for hail protection nets isn't on its own evidence for or against their effectiveness. There are a great many factors that go into such a decision and, unless you were privy to the decisionmaking process itself, whether or not nets were considered -- much less their effectiveness -- is pure speculation on your part.