Agrivoltaics: A Sustainable Synergy Between Agriculture and Solar Energy | Hacker News Reader

Agrivoltaics: A Sustainable Synergy Between Agriculture and Solar Energy

mercurialtrends.com

103 pointsthunderbong71 comments

The writing style of this article is very repetitive and drawn out. Maybe AI generated?

> Reduced Greenhouse Gas Emissions

> Agrivoltaic systems can also help to reduce greenhouse gas emissions in agriculture. Traditional farming methods rely heavily on fossil fuels for irrigation, transportation, and fertilizer production. These activities contribute significantly to greenhouse gas emissions, which contribute to climate change.

> They can also help to reduce greenhouse gas emissions by generating clean energy from solar panels. By using renewable energy, farmers can reduce their reliance on fossil fuels, which can help to lower their carbon footprint. Additionally, Agrivoltaic systems can reduce the need for conventional electricity, which is often generated from fossil fuels."

Human or AI generated, it's clearly SEO optimized. I think that's the real problem.

Really I blame Google for this, obviously any online publication needs to optimise for traffic, they need to pay the bills. But Google's latest algorithm changes quite clearly prioritise longer prose, and so bulking out text in articles has become the norm. It's a shame, and Google have the resources to do better, but unfortunately not the incentives. Most of the pages have some amount of Google ads on them.

Edit: oh okay just downvote because of an observation. Nice community here!

That there isn't an author listed other than the site name should be a giveaway that there's something funny about it.

I would assume that the biggest factor in this would be that the racks and solar panels make it very difficult to use large machinery such as tractors and harvesting machines? Somehow this isn't even addressed.

You're correct that this is limited to manual harvesting but isn't that pretty common for partial shade crops?

Partial shade crops include broccoli, asparagus, kale, carrots, brussels sprouts, peas…basically all the healthy stuff. Adding a whole second revenue stream to their production would make them more competitive with the unhealthy stuff (corn, rice, wheat).

Corn is an absolute miracle. It probably took hundreds of years for native Americans to cultivate and domesticate corn to the nutrient crop we know. Those three crops feed humanity. They shouldn’t be shunned for what modern food processing practices. The US alone produces enough corn to feed well over 2 billion people per year.

Sure, but it’s just imbalanced in people’s diets, partially because of the cost differential.

It's also pretty common to use solar fields for pasturing, especially where the slopes are too steep for heavy machinery.

these look geared towards small-scale, high $/kg farming for berries, veg, and other hand-picked food. I'd imagine anything on a larger scale for high-yield grain farming would be a waste of land

The racking is either spaced to allow machinery between rows, or panels are suspended using cables and a structure above the machinery max height. Not a consideration for crops that are hand harvested.

https://www.farmersjournal.ie/agrivoltaics-can-crops-and-sol...

https://d3mdtxxgfz6upn.cloudfront.net/WEBFILES/000/753/181/1...

If you're already putting structures in the field with the plant, I wonder if they could support the movement of smaller machines that do the same task.

Instead of driving a factory over the crop, imagine a variety of smaller robots zooming around on rails or something. Like https://farm.bot but huge.

I would also like to see that discussed. There may be enough space on the ground for more compact machinery to do a similar job. Each machine might be less productive, but they would cost less, so you could have more of them and the operation would be more parallelized.

Farm machinery got "big" because it enables one human to be more productive, cover more area in one unit of time. Human time is one of the most expensive resources in farming.

As we automate more farming, and move to self operated machinery, we can shrink those machines down again. We can design fleets of machines to work in tandem, and operate around other structures, such as solar. The age of the tram lines is going to come to an end.

This also provides opportunities for replacing chemicals with small robots, such as for weeding.

Or maybe use illegal cheap labour from another country. Something like feudalism, but more modern!

You joke, but there are a lot of crops that can't easily be machine picked, and probably never will be. Although I'm a proponent for legal safe immigration for sessional work with a route to permanent residency. The lack of legal routes results in unsafe working conditions and modern slavery.

Why would I joke? People are cheaper than machines.

Edit: "illegal" in terms of work law, minimal salary and safety standards. Legally imported workers are probably even cheaper and easier to exploit!

Until we establish socialism, human labour will always be exploited and cheaper than machines!

My mistake, I usually assume someone openly proposing illegal immigration, rather than safe legal immigration, as a solution is joking.

Ah but now supplemented with a push to legalize child labor in the US.

Child labour is already legal (to some extent) in agriculture, unfortunately.

And even more often overlooked by those benefiting from it.

I don't know about never. Strawberry picking robots seem to be in the piloting phase (out of the lab, not yet in mass production). Same with harvesting salad greens, and grape picking. Other fruits and vegetables look like just a matter of time and investment.

As we move down the robotics learning curve, prices will fall to the point where investment for designing blackberry pickers or cherry pickers (for example) is affordable.

> Human time is one of the most expensive resources in farming.

Not any more. A combine costs around a million bucks and has a total useful lifespan of about 10,000 hours which is $100 an hour (not counting maintenance and fuel costs which approx doubles this rate) which far exceeds the cost of a human operator. Capital costs exceed labor costs for almost all types of farming these days.

You might check your math here buddy. Sure a combine (which is called that because it does three jobs all at once, reaping, threshing and winnowing) may cost 100$/hr over it's useful lifespan, but it replaces much more than one person (more like 150-300 people), especially when you consider that harvesting is extremely time-sensitive, sometimes in a matter of hours...

Edit: after some research and calculations, my estimate is that a single modern combined harvester can replace between 350 and 700 men.

But it doesn’t matter how many people it replaces. TODAY it’s a capital heavy business.

Side note: textbooks like to talk about the "amazing" productivity growth in manufacturing, but that's only been something like 6 to 20 times, not 350 - 700 times.

The real story of productivity growth is in agriculture, and it's still going on, with autonomous vehicles and robotics. An amazing world we live in, where the process of growing food was capable of such incredible labor efficiency gains. Imagine if medicine was the same way...

Sorry if I seemed to imply a productivity gain of 350-700 times. This is a very rough estimate for only the tasks accomplished by a combined harvester, which happens in a very narrow timeline in the season. I was certainly not talking about the overall productivity of the farms.

Seems pretty straightforward to seeing appropriate machinery and use that instead of machinery designed for an entirely different setting.

This is a specific application of a broader design pattern found in the permaculture world: planting combinations of plants at different canopy layers, ecological functions, and yields. The solar panels would be taking the place of an understory or shrub canopy layer, while there are herbaceous, ground cover, and root zone layers you can work with.

While solar panels have an yield useful for humans, it would be even better if it can participate in the ecological system. Planting instead say, a palo verde would yield edible beans, with the tree itself acting as a nitrogen fixer. A sea buckthorne tree also acts as a nitrogen fixer, with roots propogating (more sea buckthrone trees pops up on its own) and yields high vitamin-c berries.

What ecological function can a solar panel contribute to?

How do solar panels interact with condensation?

I don’t know. But that gets into the broader design pattern of engineering a microclimate, whether that is changing local humidity and temperature levels.

Perhaps, the structure itself can also provide some other functions. The pylons, for example, can double as a way for deep root watering.

Providing shade and lowering peak temperatures - allowing sensitive plants to survive in a broader range of climate & light conditions.

That’s a result of occupying a certain canopy layer. Any other plant that occupies that canopy layer can do the same.

But 1) they don't generate electricity 2) they might require care to avoid spreading or attracting bugs (i'm speculating)

The idea to benefit from an energy source at the ecological layer is the main idea IMO.

Generating electricity is a yield to humans. Other plants have other yields.

In an ecosystem, something spreading and growing is a feature, not a bug. It means that, as a living system, it self-heals and regenerates. This is better than just being sustainable. A solar panel neither self-heals or regenerate. It in fact, degenerates —- the cells wear out over time, yielding less electricity year over year, and will require replacement at some point. Without human intervention, it will eventually stop functioning.

My question still remains unanswered: what does a solar panel contribute to the ecosystem itself, that is not a result occupying a canopy layer or a yield for humans?

Your viewpoint, as good as it is, is not appropriate here imo. It's a human need being discussed, not an ecosystem one. If you breed the best ecosystem the people will not get tangible benefits, maybe some increase in soil quality, plants resistance, nutrients but is it enough to improve their production and finances ?

At least that's how I see it with my limited information.

The shade can be controlled with tracking panels. Full shade at noon when photosynthesis stops due to heat to preserve water, less at other times.

The PV can also perform a nitrogen fixing role via electrolysis and ammonia production.

On a broader scale it can lead to the land being habitable at all by driving a coal or gas generator out of business.

Not better, but more likely to be deployed.

In order for the panels to function as a nitrogen fixer, you’d not only have to add that functionality to the panel, you also reduce the yield in order to power it.

Are people willing to do that? Are there better ways to contribute?

When designing plant guilds in this way, these are the common ecological functions plants contribute to:

- nitrogen fixer

- deep-tap root dynamic accumulator (roots bring up nutrients below most other plant’s root zones and makes it bioavailable at the surface)

- pollinator attractor (usually flowers)

- aromatic confusers (part of integrated pest management strategies)

- sentinels (helps control plants that spread, or protect fragile plants from animals)

- animal and insect habitats

Then there are keystone species that have so many contributions, the local ecology would fall apart without it. An example is a baynan, from the fig family. These are actually a parasite that takes over a host tree with invasive roots, but they are also keystone species that contributes so much that no one wants to get rid of them.

In contrast, I don’t think anyone designs solar panels like this. So it yields something with minimal participation in the ecosystem. Humans want it for the electricity, but it may as well be an invasive species that just extracts resources without really giving anything back.

One of the incentives the article doesn't mention is property tax. Where I live, agricultural land is taxed much less than other property. The moment you put solar on your meadow you pay the regular rate. I think it would be fair if property kept its agricultural tax status if it is used in an environmentally friendly way.

But in turn, this means that solar plants will be developed to have pretend-farming below it.

Not at all. My opinion is that you should be taxed the same way no matter how you use the energy that falls on your soil from the sky. It shouldn't matter if it goes through chlorophyll or silicon.

So you’re saying that solar farm land should be taxed like farmland?

That would remove the bad incentives. Personally I agree.

How difficult would be to have some checks for actual farming taking place ?

If this allows for more solar farms AND give people incentives to also grow more food locally I'd say it's a win-win.

PVs are always raised off the ground.

This is not some new invention, people just planted some stuff under the PVs.

You can also get some goats to clean the weeds in the place before that. They will appreciate the shaded area (but hopefully not the cables)

> PVs are always raised off the ground.

Not true.

https://www.erthos.com/

Do we have electric tractors?

Are they viable given that weight is a serious issue for machinery on fields?

Having lived on a rural farm, with solar panels on the barn, if you can use the harvested power on the farm, great, but once you start trying to distribute it, the problems start to show up because rural infrastructure isn't good, and there isn't enough demand in the local grid.

Sounds feasible. You’d need battery storage or less batteries and orchestration to charge farm equipment during solar production hours if no grid connection available, but micro grids are a well worn path at this point. Very popular in Australia’s western geography and their Northern Territory, where there is not much transmission infra to speak of.

https://electrek.co/2022/11/23/caterpillar-demonstrates-firs...

> infrastructure isn't good

I've heard this enough times that I might assume this is the bottle neck of a green transition of our electrical generation. What is being done about this? Is it an area where innovation or disruption can still happen? Are there any interesting things on the horizon for taking big leaps on fixing the electricity infrastructure? As a Fullstack/Cloud/Data engineer where could you put your feet down to contribute to solving this problem?

Decentralized power isn't what the power companies want.

The innovations aren't being pursued because of economics and greed.

So let's decentralise (human) power (over the grid)? But how?

The entire reason it's being done is the 3% of farmland which is sitting directly on interconnect is more than enough for all the solar that is needed and reactionaries keep having a hissy fit at the idea of replacing topsoil destroying and water polluting energy corn with less polluting PV. You can't then turn around and whine that the transmission line is too far away. Just don't build it on the other 97% of the farms.

Having solar panels might be a good way to hedge your bets against a bad harvest. I imagine it can get quite sunny during a drought.

Plants love sun, why would I put them below a panel into shade.

Article mentions blueberries which I grow and those which get the sunshine only half of the day (partly in shade) don't have the same sweet taste as other in better sunny spots of my garden.

You can get bifacial panels that let light filter through. Not sure what is filtered, but perhaps the remainder is sufficient for certain crops?

Here is a chart of DLI (daily light integral) needed for lots of common crops.

https://www.horti-growlight.com/en-gb/typical-ppfd-dli-value...

Here is a map of DLI in the USA by month.

https://www.researchgate.net/figure/Maps-of-monthly-outdoor-...

So there is some wiggle room maybe. Looks like about 30 is good DLI and the USA gets 40-60 in the summer.

My gut feeling though tells me that the best performance is panels that use all the light or plants that get full access to it.

Plants can also get too much Sun just like they can be overwatered.

That’s where agrivoltaics and irrigation can help.

This would vary so much by species of plant, cultivars within species, local climate, etc. I suspect in your case it wouldn’t make sense, but in some places it’s a common practice to shade crops with raised sheets of cloth for example. In those cases, assuming the shading is done fairly consistently (no need to put panels up and down frequently), using panels could be a great idea.

Where I live I need all the sun I can get as well. I have to start tomatoes in mid February and get them into the soil in June, and make sure they’re either in my greenhouse where it’s warm or in the most exposed spots in my garden. If I shaded anything my yields would be garbage.

> Plants love sun

No. Some plants love direct sunshine and others don't.

Unfortunately the article just hand-waves on this point, leaving it at "certain crops":

> However, certain crops are better suited for this system due to their ability to thrive under partial shade.

They do love sun, but they might not like intense heat.

Take those blueberries, Mine hate being in certain parts of the patio because whilst they get full sun, they also get longer and more extreme levels of heat. I almost lost them the year before last.

(this is with a decent irrigation system too)

Your anecdote is definitely better than all of the science showing quality and yield improvements.

Agrivoltaics seems like a cool idea but one of the things I rarely ever see mentioned is how chemicals from the panels interact with the crops. Steel can rust and if rust gets washed away into the earth and then the plants... well that cant be beneficial right? And I bet steel is the least toxic element of the panels.

There are plants that can do soil remediation on soil with heavy metals, though you can’t eat them and you still have to find a way to process or sequester the heavy metal. Cilantro (coriander) is an example.

Iron is often used as a fertilizer, so rusted support beams aren't a problem, either for the plants or for humans. And all the interesting parts of a solar panel are under glass, they aren't being washed away by rain.

Rust is just iron oxide, which in small quantities is a relatively benign substance. And probably there's more rust coming from old farming equipment than from the (likely high quality, because they are built for expensive solar panels) steel structures here.

The solar cells themselve are mostly made out of silicon, which also isn't a dangerous substance.

I don't think this is an issue.

the solar facilities i'm familiar with use aluminum beams for the structure. it is more than strong enough, lighter so it is easier to install/ship to site, and requires no special treatment to survive the environment for more than the life of the installation.

the panels themselves do not contain steel, either.

> And I bet steel is the least toxic element of the panels.

perhaps, but nothing on the panels comes off. they're solid objects largely impervious to all forms of precipitation. more of your house washes away in a storm than comes off a panel.

Steel structural members used outdoors are coated, normally with zinc (called galvanizing). You see rust when the galvanizing has been corroded through. Sometimes a zinc + aluminum alloy is used as it lasts longer than pure zinc.

You should be more worried about those elements washing into the soil. But it turns out that zinc is an essential micronutrient (as is iron) and aluminum is a large part of clay soils anyway.

Other components of solar modules, roughly in order of mass:-

- Glass. This is heavily purified and baked soil. Not a problem.

- Silicon. This is the reduced metallic form of dirt, the equivalent of steel compared to rust or iron ore. Rusted silicon is all around anyway.

- Aluminum wires and connectors. Already covered.

- Plastics used to insulate wiring. Here we might have a problem, with microparticles wearing off and entering our food. However, the effects of this are not at all obvious - people are not dying in millions from agricultural plastics, used for example on the ground as weed suppression around strawberry plants. More research is needed.

By comparison with other uses of plastic in agriculture, the scale of this is tiny.

- Copper internal wiring and connectors. Copper has been used for centuries as a crop spray, and it is permitted in nearly all "organic"/"green" farming certifications.

- Silver, in tiny amounts as top conductors on panels. Has antimicrobial properties in certain chemical formulations, but note the "tiny". Almost certainly benign, and if there is enough of it in the soil (well below any possibly toxic level) it will be recovered for re-use.

- Trace amounts of "exotic" elements in the silicon. If these make their way into the soil, it will be in concentrations of parts per trillion, likely far below background levels already in the soil. (Some of these are things like phosphorus which is an essential nutrient anyway.)

There is lead too in some, but even if it all somehow teleported out of the module and directly into the soil (as opposed to this never happening) it would be 10% as much as was already in the soil naturally before leaded gasoline was a thing.

That's because it's a purely imaginary problem shills invented.

Vastly higher quantities of toxins and heavy metals come out of the tractor exhaust than will somehow teleport through glass and time-travel from obsolete chemistries.

Reply on news.ycombinator.com