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Comment by cschneid | Hacker News Reader

Something that's interesting is that most of our agricultural crops are bred for full sun (ie, a big flat field). I wonder if there's room for new partial-shade versions of crops, so they work better alongside solar panels. I doubt they'd be as productive in an absolute sense (less light = less total energy), but adding on solar panels value to the output of that land would likely be better than single-use of either.

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There are many studies examining the potential of agrivoltaics (it even has a Wikipedia page), and they find just as you suggest: the combined output of electricity + crops is better than doing either one alone, but the electric and crop is a bit less than devoting the field to either purpose solely, as it would need to be.

Efficiency increases are often 30% or more.

Some people get really, irrationally upset about solar being put on farm fields, but it really helps both the farmer and society to do that.

Actually, given the high investment costs for dual-use of solar and crops, it is economically better to just do each separately and commit the area fully to one or the other. That was the essence at least I got from an article about agrivoltaics in Germany.

I would like to see that article, as it runs contra the messaging I've heard from other studies over the past few years.

It may depend a bit on the actual location. Germany has some of the very very worst solar conditions of anywhere in the world, worse than pretty much all of the US, and I've been primarily looking at studies with solar resources at US levels. I wouldn't be surprised if Germany has different solutions than most of the est of the world.

It wouldn’t surprise me too if some of the studies in the US were places like Arizona, where too much sun is an issue for many crops (sun spotting, burning of leaves, excess water consumption), and some shade during peak insolation is not only beneficial for crops, but if you can do something with the energy? Even better.

One really beneficial coupling in a lot of cases seems to be HVAC + solar in hot western climates.

I wonder if we could store cold for an HVAC in hot climates the same way a sand battery works.

The poor man's version of this might look like this:

1- Connect your solar panel directly into a big freezer.

2- Fill your freezer to the brim with bottles full of saltwater.

3- Let it run to the coldest temperature possible.

4- Drill two ventilation holes (inlet up / outlet down) and connect to a small fan sucking the cold air where you need it.

Anyone knows something like this?

This exists for big refrigerated warehouses. By using an appropriate liquid with the phase change tuned for the working temperature you can shift the electricity usage to times with lower cost. That can be because you have your own generation or are just buying market rates that vary.

I think it's more that there's likely better land to put it on. In the UK for example there's arable land growing corn or cows or whatever, and there's scrub moorland which is closed from the public and used to shoot grouse once a year.

If you have 100 acres of solar to put on land, better to put it on the grouse moor.

But in what sense is it better to use grouse moor? That's habitat that is not currently touched much, and is a good reservoir for natural ecology, right? There's value in that.

The grouse moor is basically a grouse farm. The moor is periodically burned to promote the right kinds of growth, 100s of grouse are released and nature like birds of prey somehow end up with a shorter lifespan.

I thought they banned burns?

In any case, I will cede the environmental case to local ecologists. But if it's already farming of grouse, that seems less intensive use than farming of sheep, as an outsider I would be interested in learning more as to why grouse moors are preferable to sheep land. It seems that grouse moors would be far more amenable to rewinding. But as I said, I only have my non-expert opinion!

There's a partial ban that covers some of the most sensitive areas, probably 90+% of the grouse moor burning that happened before, still happens. You can see reports at https://twitter.com/wildmoorsuk.

I agree with you and would rather not see grouse moor turned to solar farms. I'd love to see more moor rewilded, the work that Moors for the Future is doing is amazing. Grouse moors are very much touched and managed though. Gamekeepers seek to minimise foxes, stoats, raptors and trees.

Presumably because the solar infrastructure gets in the way of the corn, but is unlikely to matter much for some grouse?

It really is touched a lot. The landscape is basically grouse farming.

They put hundreds of birds into those fields every year so that hunters have something to shoot. I wouldn't call that untouched.

The problem is, how do you navigate a tractor around the panels? Animals are a much better fit in that regard

Buy appropriately sized tractors. Typically farmers are upgrading these things all the time, should be pretty straightforward to swap out this single factor of production to the right sort of thing.

Our vehicles and machinery have this tendency to occupy prime mental real estate, as unchangeable monoliths around which everything must be planned. In reality, they are the most changable thing, and we must change our machinery to serve us, rather than the other way around.

There are also lots of crops that are not serviced by large tractors, but individual human hands. In fact most of the fruit and vegetables we eat are like that, and many of those crops do very well with a bit less than full Sun.

you either go up (expensive) or wide (less economical, lower energy yield)

Permaculture and agroforestry touch on this a lot. In permaculture designs usually photosynthesis per acre is maximized by planting guilds of crops that work well together – in this case, larger trees with shade-loving shrubs beneath them, and beneficial ground cover beneath them as well.

Towards the more conventional end of agroforestry, rows of trees are separated with rows of crops, grains, etc. There's lots of benefits to this way of farming, though it's still 'new' to a lot of people.

I think the crop or the plants would have to change a lot. Currently it's pretty easy to see which areas get full sun and which don't when you drive by a corn field in growing season.

Looks like its being tested though https://www.canarymedia.com/articles/food-and-farms/can-agri...

> most of our agricultural crops are bred for full sun

Some crops need shade, most often berries. Shade in Spain and Shade in North Scotland are very different of course.

Ginseng needs shade(1), farmers should install solar over ginseng crops. However, I suspect they need to drive equipment through at times. I wonder if there are solar installations where the panel can go perpendicular to the ground to allow tractors through?

1 - https://www.google.ca/search?q=ginseng+field

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