Live data from Hacker News

Semi-transparent solar panels allow concurrent production of crops and power

onlinelibrary.wiley.com

201–210 of 226 posts

Re: Semi-transparent solar panels allow concurrent production of crops and power

#201
post #52
post #11

Earlier quoted context omitted.

Vehicles often crash into things beside a highway.

Planes sometimes fall on people's roofs. Let's not optimize for edge cases here?

The entire reason medians exist is because they are a crash safety device. Consideration for crashes is not an edge case, it’s the entire point of a median.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#202
post #117

I always wondered why you could not just place the panels a bit higher. So that the sun can pass on certain times etc.

Yeah, people are treating this solar panel like a hammer and finding any use-case that looks like a nail.

Instead of a entire roof of panels that pass 50% of the light, it’s is more simple to make a roof of half covered in panels that pass 0% of light... like a pergola.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#203
post #50
post #34

Earlier quoted context omitted.

I've been living in the west my whole life and have traveled between Colorado to California through Nevada, Utah, Arizona, etc 7 or 8 times, so yes I've seen an empty western road before. Tumbleweeds was tongue in cheek but there's plenty of dirt, trash and other flying debris that will get baked onto a glassy surface out southwest.

Well, even in the Sahara there's sand and sandstorms piling it on solar panels... There's no place that's 100% immune from all dirt/leaves/etc. Still shouldn't be much of a problem in practice...

I agree on both. It (degree fouling of the solar panels) is a fact of things, but shouldn't impact things much pragmatically.

I think that we can expect the same amount of accumulation of stuff as we currently get on these roads. Its not like we're out there street sweaping these rural highways, but they're also not covered in debris.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#204

Not just crops and power. I know a guy whose startup is using transparent solar panels in Germany on eco-friendly buildings with grass on roofs, to get power and eco-cooling, as well as Oxygen production - at least that is how he explained it. The concept is called green-roofs. Unfortunately I don't remember his startup's name. A link with details about the concept, minus the use of transparent solar panels: https://…

I'm also considering making a green roof. Apparently, since the plants (sedum/stonecrops and mosses) help cool the roof, the solar panels on top of it are a bit cooler too increasing their efficiency. It also helps retain some water so it does not go to the sewer directly after it rains of the roof and keeps the sewer from getting overloaded. Another claimed benefit it is that a green roof helps reduce fine particula…

Depending on the style of house, it also makes better use of space if you're otherwise trying to balance space for gardening or for your children to play, etc. I would love to be able to grow my vegetables on the roof and free up the ground level of a basketball ring or more lawn for the kids.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#205
post #133

Earlier quoted context omitted.

A thing that they are good at however, is lowering temperatures in cities (compared to e.g. stone surfaces which store the warmth of the sun) – this alone might be a good reason to look into green roofs, given that we just passed the point of no return for Greenland's ice sheet recently. It takes the same amount of energy to melt 1kg of 0°C ice into 0°C water as it takes to heat 1kg of 0°C water to 80°C.

I wonder how that compares to white painted or even reflective roofs? The paint solutions don't require a gardener at least.

Usual white painted surfaces get hot too. And if you use some superhigh-reflectivity surface, you have to keep it clean.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#206
post #111

Only people who spend most of their life in densely crowded cities could think that the planet has so little space that you'd need to grow crops underneath solar panels for efficiency's sake.

And only someone blind to the ecological damage that agriculture does would regard all that land as free to use by humans, without consequences. Here [0] is a map of the world's remaining wilderness. Notice how it's nearly all desert, with the exception of the Amazon rainforest. And hey, guess what's happening to that? We are short of space. And time. [0] https://images.theconversation.com/files/256144/original/fil..…

What's the definition of wilderness used on this map? The only wilderness area on the map that I've been to is the Okavango delta (which is amazing btw), but in terms of remoteness (lack of people/infrastructure) it's not that different from many of the surrounding areas

Re: Semi-transparent solar panels allow concurrent production of crops and power

#207
post #178

Earlier quoted context omitted.

You probably need to have a irrigation keep the plants alive. Probably spraying the concrete surface has the same effect.

You would have to spray the surface every day, plants need watering much less, close to never if they're native to the region.

>>> A thing that they are good at however, is lowering temperatures in cities

Plants are not magical, so if they get the same solar light influx then: (choose at least one)

a) They are actually not good keeping the temperature down?

b) The have more reflectivity, i.e. they are more white? (but I think they are darker)

c) The complex structure provides some air flow that keep the plant and soil cooler? (like the isolation of fur in animals, but in the other direction)

d) The specific heat of plants is greater than concrete? (plants have more water, and water has a big heat capacity)

e) The big heat capacity is due not to the water in the plant, but to the water in the soil?

f) The difference of temperature is caused by transpiration of the plant? (water has a huge heat of vaporization, plants try not to loos too much water in transpiration anyway)

g) Most of the evaporation is water that was in the soil?

For f) and g) two you need irrigation. Perhaps not daily because plants and soil are better storing water than concrete, but it is the same amount of water.

For d) and e), you need less irrigation, but perhaps it is better to have some kind of water tank of pipes, to avoid water lose.

For c) you can try with artificial grass. Does it work? Is it easier to maintain?

For b) it is probably better to use and aluminium foil cover (they are popular here it rooftop to avoid rain leaks)

Re: Semi-transparent solar panels allow concurrent production of crops and power

#208
post #111

Only people who spend most of their life in densely crowded cities could think that the planet has so little space that you'd need to grow crops underneath solar panels for efficiency's sake.

And only someone blind to the ecological damage that agriculture does would regard all that land as free to use by humans, without consequences. Here [0] is a map of the world's remaining wilderness. Notice how it's nearly all desert, with the exception of the Amazon rainforest. And hey, guess what's happening to that? We are short of space. And time. [0] https://images.theconversation.com/files/256144/original/fil..…

Except most of the "agriculture" damage occurs due to meat production: https://en.wikipedia.org/wiki/Environmental_impact_of_meat_p...

"In the contiguous United States, 127.4 million acres of crops are grown for animal consumption, compared to the 77.3 million acres of crops grown for human consumption.[23]"

Re: Semi-transparent solar panels allow concurrent production of crops and power

#209
post #204

Earlier quoted context omitted.

I'm also considering making a green roof. Apparently, since the plants (sedum/stonecrops and mosses) help cool the roof, the solar panels on top of it are a bit cooler too increasing their efficiency. It also helps retain some water so it does not go to the sewer directly after it rains of the roof and keeps the sewer from getting overloaded. Another claimed benefit it is that a green roof helps reduce fine particula…

Depending on the style of house, it also makes better use of space if you're otherwise trying to balance space for gardening or for your children to play, etc. I would love to be able to grow my vegetables on the roof and free up the ground level of a basketball ring or more lawn for the kids.

It's a bungalow so all ground level living (not just handy when you're old but apparently also when SO just delivered a baby) so the roof is also mostly flat.

I've considered adding a vegetable garden on the roof too, or maybe just herbs. And thought about a terrace on the roof too, that would be cool but the ground-level garden is nice already as it is.

Re: Semi-transparent solar panels allow concurrent production of crops and power

#210

Earlier quoted context omitted.

So what on this earth is producing useful amounts of oxygen then?

Algae in the ocean, mostly. But also, any growing plants - you could compute for every kg of dry plant matter, how much oxygen is released, as the dry plant matter is almost entirely carbon produced from breaking up CO2. So unless you're collecting tens or hundreds of kilograms of dead plants from your roof every year, it isn't producing much oxygen.

And algae are plants last time I checked.

Because op said "Plants don't produce any useful amount of oxygen"

And I am aware, that room plants do not really add meaningful O2 to the room, their value is in humidifying.

Post reply on HN