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

onlinelibrary.wiley.com

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

#171

Post by chris_engel »

dghughes wrote: post #85

My mother ayed tomatoes in the spring when it was still cool. She covered them with clear plastic bags as she always has. But she needed one more bag so she used a blue recycling bag on one of the plants. Blue tinged really it's almost clear. I pointed out to her one of the plants had yellow leaves. It was the plant with the blue bag. Later in the summer the blue bag plant produced fruit just like the other plants. B…

A blue plastic bag filters most of the spectrum EXCEPT the blue part. Not the other way around. Simple proof: look inside, the light is blue.

I guess the biggest problem for the plant here is that especially the infrared part of the sunlight is very important. Yellow leaves usually mean not enough light. Especially tomatoes need lots of sunlight.

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

#172

Post by SECProto »

recuter wrote: post #168
hutzlibu wrote: post #147

Earlier quoted context omitted.

I don't really like having to watch some youtube video, to get the counterpoint, all presented in a non friendly way. So do you have some facts, you want to share, why green roofs, a method for example used in scandinavia for a long time, is bad, if done right? Because you quote ... is not a smart one. Because dirt is definitley insulation. And soild is more than dirt btw.

I didn't mean anything in an unfriendly way. The quote is not dumb but it needs a lot of context I suppose that might be missing.. definitely the key point is "if done right". I can't really condense the video for you, the guy in it does throw in a bunch of jokes from the perspective of a frustrated Canadian building science guy that might put you off but his information is great. My best attempt at a condensed parab…

> the guy in it does throw in a bunch of jokes from the perspective of a frustrated Canadian building science guy that might put you off but his information is great.

As someone else who works with civil (but not structural) engineering in Canada, I agree to a certain extent with his points, but found his tone incredibly condescending and offputting. For example:

> Does the dirt, grass, and a goat make it work better? No. But you just feel better about yourself. I mean dirt is not insulation, it's just freaking dirt. If it was insulation we'd put it in our walls, and that'd be stupid. [...] 'well we can store water up there' - Why? You're an idiot. The whole idea of a roof is to get the water off of the damn roof.

- Soil is insulating, just with a very crappy K value. You wouldn't use it somewhere that was space sensitive (eg a wall). You wouldn't use it instead of other insulation. But it is absolutely an insulator (that's why we only have to put frost walls 4-8feet deep to prevent frost heave). If your only goal is to insulate the roof better, install an extra inch of rigid foam rather than a foot of soil, it'll work the same.

- Storing water where it first strikes is good for reducing site runoff (with safeties installed to cope with bigger rainfall events).

> I once found myself driving around with a very environmentally minded person and she refused to turn the AC on in her car but cranked open the window instead.

How fast were you driving? There's a breakeven point, depends on the car - I know with mine, it's about 80 km/hr (slower than that, open the window. faster than that, AC is more fuel efficient)

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

#173

Post by chii »

samatman wrote: post #125
Retric wrote: post #19

Earlier quoted context omitted.

Rooftop photovoltaic is currently more expensive, less efficient, and surprisingly dangerous to install. Solar thermal designs actually benefit from being on rooftops. As to dust, economies of scale make a huge difference. It’s rarely worth it, but using a farm truck to spray water across miles of panels is much more efficient than tens of thousands of homeowners doing the same.

It's also unattractive, which should matter to us. Much of the distinctive beauty of traditional building in sunny areas comes from the roofs. Solar tiling, which is still not a mature technology, doesn't add danger: we have to put something on a roof, and if installing solar tile takes extra time, it isn't by much. And it looks good. Less efficient and more expensive? Sure. But as the meme would have it, it's free r…

> unattractive

people used to say wind turbines are unattractive. Culture determines what's attractive, and it can be made to look nice.

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

#174

Post by tehjoker »

quotemstr wrote: post #116
tehjoker wrote: post #98

Earlier quoted context omitted.

There's not enough nuclear fuel in the world to power the world for more than a little bit (iirc 30 years). It can at best be used as a transition source or a supplemental source.

> There's not enough nuclear fuel in the world to power the world for more than a little bit This claim is simply false. The argument in favor of this view involves a very narrow interpretation of proven reserves that excludes discovery. The argument you're making is the same as peak-oil-ism, and we all know how that turned out. https://www.world-nuclear.org/information-library/nuclear-fu...

Thanks for the link. I guess I hadn't read enough about this. I still am uneasy about using nuclear power for everything because of the risks and waste. I'm aware that alternate, safer designs exist though they are not commercially proven and often have unsolved problems with either logistics, scaling, or non-proliferation.

I feel that changes to lifestyle and solar power sharing across large geographic areas might be a better and more ecological approach, though I can't quantify how everything would work yet.

The other aspect to discovery though is that mining ever more hard to recover fuels results in escalating ecological damage. Fracking isn't something we needed to do but is possibly responsible for small earth quakes and various kinds of local destruction and pollution for example. I don't know much about uranium mining, but I suspect that it is a very toxic enterprise filled with radioactive acids and tailings.

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

#175

Post by remarkEon »

asquabventured wrote: post #166
dawnerd wrote: post #154

Earlier quoted context omitted.

All of my plants this year have gotten blossom rot, pretty much too late to fix too. No tomatoes for me this year.

Blossom end rot is caused by calcium deficiency. Easiest solution for this is to just crush up egg shells and put them in and on top of the soil. I save my eggshells in a jar in the fridge for a few months prior to planting. It may be too late for this year but should work wonders for you in the future.

Seconded, I would do this with my mom each year in her garden when I was a kid. Works 100% of the time, and it's a non-invasive way to address the issue.

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

#176

Post by i-am-curious »

chris_engel wrote: post #171
dghughes wrote: post #85

My mother ayed tomatoes in the spring when it was still cool. She covered them with clear plastic bags as she always has. But she needed one more bag so she used a blue recycling bag on one of the plants. Blue tinged really it's almost clear. I pointed out to her one of the plants had yellow leaves. It was the plant with the blue bag. Later in the summer the blue bag plant produced fruit just like the other plants. B…

A blue plastic bag filters most of the spectrum EXCEPT the blue part. Not the other way around. Simple proof: look inside, the light is blue. I guess the biggest problem for the plant here is that especially the infrared part of the sunlight is very important. Yellow leaves usually mean not enough light. Especially tomatoes need lots of sunlight.

Nope. If the bag looks blue that means it's scattering away blue light while letting the rest through. So it's filtering (out) the blue. OP is right.

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

#177

Post by recuter »

SECProto wrote: post #172
recuter wrote: post #168

Earlier quoted context omitted.

I didn't mean anything in an unfriendly way. The quote is not dumb but it needs a lot of context I suppose that might be missing.. definitely the key point is "if done right". I can't really condense the video for you, the guy in it does throw in a bunch of jokes from the perspective of a frustrated Canadian building science guy that might put you off but his information is great. My best attempt at a condensed parab…

> the guy in it does throw in a bunch of jokes from the perspective of a frustrated Canadian building science guy that might put you off but his information is great. As someone else who works with civil (but not structural) engineering in Canada, I agree to a certain extent with his points, but found his tone incredibly condescending and offputting. For example: > Does the dirt, grass, and a goat make it work better…

You got the gist of what I was saying which is physics is at play and the answer is always "it depends". But people don't like that. Hence, AC off I'm a good person. Green roof I'm a good person. 'etc.

> I agree to a certain extent with his points, but found his tone incredibly condescending and offputting

That kind of says it all, doesn't it?

Personally I found it good natured tongue-firmly-in-cheek conspiratorial humour. Considering he is an actual authority on the subject and has seen a lot of incredibly idiotic behaviour and expensive and downright dangerous mistakes I think you can forgive him if his comedy schtick is not to your taste as long as the info is good.

This talk is even better: https://youtu.be/rkfAcWpOYAA

He seems like the grumpy Linus of the building science world and if he is a jerk he is my kind of jerk.

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

#178

Post by flukus »

gus_massa wrote: post #134
atoav wrote: 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.

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.

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

#179

Post by natcombs »

i-am-curious wrote: post #176
chris_engel wrote: post #171

Earlier quoted context omitted.

A blue plastic bag filters most of the spectrum EXCEPT the blue part. Not the other way around. Simple proof: look inside, the light is blue. I guess the biggest problem for the plant here is that especially the infrared part of the sunlight is very important. Yellow leaves usually mean not enough light. Especially tomatoes need lots of sunlight.

Nope. If the bag looks blue that means it's scattering away blue light while letting the rest through. So it's filtering (out) the blue. OP is right.

If you see blue on BOTH the outside of the bag and the inside, what does that mean? I’ve never thought of this.

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

#180

Post by nostoc »

i-am-curious wrote: post #176
chris_engel wrote: post #171

Earlier quoted context omitted.

A blue plastic bag filters most of the spectrum EXCEPT the blue part. Not the other way around. Simple proof: look inside, the light is blue. I guess the biggest problem for the plant here is that especially the infrared part of the sunlight is very important. Yellow leaves usually mean not enough light. Especially tomatoes need lots of sunlight.

Nope. If the bag looks blue that means it's scattering away blue light while letting the rest through. So it's filtering (out) the blue. OP is right.

No, a blue filter, like a blue plastic bag would let blue pass and absorbe the other colors. That's why if you shine a white light through a blue filter, things look blue on the other side.

Now, some of the blue light is scattered away, and that's why you see the plastic bag itself as blue.

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