Author Topic: EEVblog #743 – Solar Roadways Test Results  (Read 45984 times)

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Offline DanielS

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #50 on: May 14, 2015, 03:04:32 pm »
Dave, your obsession with comparing this to roof top solar made you completely miss the point of the project.
Dave's point is simple enough: putting solar panels in the ground is many times more costly and half as efficient. It simply does not make economic sense. Raised solar panels cost half as much to install and produce twice as much power.
« Last Edit: May 14, 2015, 04:42:14 pm by DanielS »
 

Offline Fungus

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #51 on: May 14, 2015, 05:31:43 pm »
Dave's point is simple enough: putting solar panels in the ground is many times more costly and half as efficient. It simply does not make economic sense. Raised solar panels cost half as much to install and produce twice as much power.
...
c) Will need a fraction of the maintenance.

« Last Edit: May 14, 2015, 05:46:24 pm by Fungus »
 

Offline miguelvp

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #52 on: May 14, 2015, 05:38:41 pm »
This was a pilot project. An experiment. Government funded.
No company nor individual will ever pay for non-profitable solar roads from non-pr budget. Or at least, healthy companies shouldn't.

The problem with Government funded is that the money comes from taxes that could have produced good returns instead of votes.

I would think the approval rate for that project as perceived by the general public is good and green and the return is votes.
So mission accomplished!
 

Offline max_torque

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #53 on: May 14, 2015, 06:58:39 pm »
We need 1 year to establish things.

No, no we don't!

  By comparing the solar cycleway to the normal roof top solar instalations, that were within a few Km, we already have a direct comparison because the same amount of sun light fell on both systems during the test period.

It doesn't matter for how long we test it, the comparison is valid in terms of $ per kWHr , which is ALL that matters.


(hint, i have two packets of crisps to sell.  Packet A is 50grams and costs $0.20, Packet B is 25grams and costs $3.  Which one would you like to buy??  ;-)

Read my answer... This is what I did. But I guess reading more that one line and quoting it out context is all you can do.

I have ready you original answer, and like a lot of people who seem to think solar roadways are viable, you are missing the critical point, which is:

THE ABSOLUTE AMOUNT OF ENERGY PRODUCED BY A SOLAR ROADWAY IS NOT IMPORTANT!

The only thing that is important is:

THE COST OF THE ENERGY PRODUCED ON A $/kWHr BASIS.


So, you have a cloudy year and  your solar road way only makes 100kWhrs in total.  But a roof top installation of the same surface area (and vastly less cost) will produce roughly 200kWhrs.

So you have an amazingly "sunny" year and you solar road way makes a massive 100,000kWHrs in total.  But a roof top installation of the same surface area (and vastly less cost) will produce roughtly 200,000kWHrs.


In ALL cases, the higher efficiency (tilted panels, thinner, cleaner glass)  and lower installation costs means that the conventional roof top solar installation will have something like a 4x faster ROI than your solar roadway.  In our Capitalist economy, that is the only thing that matters!
 

Offline eneuro

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #54 on: May 14, 2015, 07:38:18 pm »
In ALL cases, the higher efficiency (tilted panels, thinner, cleaner glass)  and lower installation costs means that the conventional roof top solar installation will have something like a 4x faster ROI than your solar roadway.
Hybrid solar PV & thermal solar & savonius wind turbine is better choice while beter exploits weather conditions-cloudy windy days for savonious and clear sky for thermal solar with a few time better efficiency than solar PV, which are good to power up home electronic in more efficient energy harversting system like solar thermal and savoius wind turbines  ;)

« Last Edit: May 14, 2015, 07:43:10 pm by eneuro »
12oV4dWZCAia7vXBzQzBF9wAt1U3JWZkpk
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Offline MauriceS

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #55 on: May 15, 2015, 03:07:41 am »
BTW, I saw the Solar Roadways wiki page has links to Dave's videos and added this last one.
It got removed because: "When the guy becomes a member of the national academy or wins a pulitzer or something then I can see his own blog qualifying for an exception to the blog rule, at least to the extent that he has certain opinions based on original speculation-based guesswork. "

The editors don't get ENGINEERING practices, where one can make guestimates.
Solar Roadways Wiki Talk

And also because SR didn't release any of their results (which they never will): "To my knowledge, the details of Solar Roadways' R&D are still proprietary, rendering any "detailed analysis" dependent entirely on speculation. It might be generally informed, with knowledge of the current state of on the shelf technology, but he has to guess what on the shelf technology might be used, and he has to assume the company has not invented any new components, materials, or combinations. Informed speculation is still speculation. In short, this guy is engaged in educated guessing on his blog, and that has ZERO WEIGHT."
« Last Edit: May 15, 2015, 03:09:24 am by MauriceS »
 

Offline bitwelder

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #56 on: May 15, 2015, 05:20:59 am »
It got removed because: "When the guy becomes a member of the national academy or wins a pulitzer or something then I can see his own blog qualifying for an exception to the blog rule, at least to the extent that he has certain opinions based on o
So, do we need the calculations published in an article on some printed magazine to make it acceptable?
 

Offline EEVblog

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #57 on: May 15, 2015, 05:33:26 am »
We need 1 year to establish things.

No, no we don't!

  By comparing the solar cycleway to the normal roof top solar instalations, that were within a few Km, we already have a direct comparison because the same amount of sun light fell on both systems during the test period.

It doesn't matter for how long we test it, the comparison is valid in terms of $ per kWHr , which is ALL that matters.


(hint, i have two packets of crisps to sell.  Packet A is 50grams and costs $0.20, Packet B is 25grams and costs $3.  Which one would you like to buy??  ;-)

Read my answer... This is what I did. But I guess reading more that one line and quoting it out context is all you can do.

Your calculations have no relevance to what max_torque  is saying.
In my video I got the data from the solar road and nearby rooftop solar system and compared the output per square area over the exact same period. Rooftop has has double the output of SolaRoad, and that's all that really matters. You could have used a weeks worth of data and got the same result.
 

Offline EEVblog

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #58 on: May 15, 2015, 05:35:08 am »
50 years ago, financially practical solar power was just around the corner.
50 years later, today, it is still just around the corner.

Huh?  :-//
The payback period on my system is in the order of 5 years.
 

Offline EEVblog

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #59 on: May 15, 2015, 05:36:13 am »
Dave, your obsession with comparing this to roof top solar made you completely miss the point of the project.
Dave's point is simple enough: putting solar panels in the ground is many times more costly and half as efficient. It simply does not make economic sense. Raised solar panels cost half as much to install and produce twice as much power.

Yup, that!
 

Offline EEVblog

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #60 on: May 15, 2015, 05:46:42 am »
BTW, I saw the Solar Roadways wiki page has links to Dave's videos and added this last one.
It got removed because: "When the guy becomes a member of the national academy or wins a pulitzer or something then I can see his own blog qualifying for an exception to the blog rule, at least to the extent that he has certain opinions based on original speculation-based guesswork. "

Wow, I thought the inclusion of criticism in that wiki article was well placed by whoever it was. Given the number of people speaking out against Solar Roadways it certainly deserves a "Controversy" section highlighting legitimate complaints. You could easily add a dozen blogs and articles critical of Solar Roadways.

Quote
(A) its a blog, (B) its still speculation because he's guessing as to the particulars. We don't publish speculation. If you've got heavy hitters expressing dubious skepticism, we should be able to add fact they think so that in NPOV)

How is the world's biggest electrical engineering channel with 240,000 subscribers and 300,000 views on the critique video not "heavy hitting"?
What do they want, and official article in the IEEE?
The fact that there are many critiques of the project is noteworthy enough to at least includes links to them and mention them.
« Last Edit: May 15, 2015, 05:52:12 am by EEVblog »
 

Online Monkeh

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #61 on: May 15, 2015, 10:03:43 am »
How are you going to take money from the paving budget and transfer it to building maintenance?

The same way you'll increase the budget for materials by in excess of an order of magnitude.

Seriously, stop dreaming.
 

Online Monkeh

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #62 on: May 15, 2015, 12:06:41 pm »
How are you going to take money from the paving budget and transfer it to building maintenance?

The same way you'll increase the budget for materials by in excess of an order of magnitude.

Seriously, stop dreaming.

You have no idea how budgeting works in large organisations, do you?

Ill-educated idiots ask for money for poorly thought out ideas and get it?
 

Offline MauriceS

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #63 on: May 15, 2015, 02:05:32 pm »
I'm amazed how many so-called science magazines and websites are publishing this as the best since sliced bread - and they don't even do their due diligence. They just publish the Solar Roadways information the truth, but it isn't more than an advertisement.

And every positive publicity gets linked on the SR site as that...

And looking at the comments, everyone who is in favor of it, turns their brains off. It's solar, it's renewable, so it must be good, and they do not listen to any of the well thought out arguments.

But I doubt w'll never see actual true numbers from Solar RoadWays... I'm sure their lawyers would say - "If you publish those - you'll have a class action suit on your hands!"
 

Offline mullecy

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #64 on: May 15, 2015, 02:12:47 pm »
We need 1 year to establish things.

No, no we don't!

  By comparing the solar cycleway to the normal roof top solar instalations, that were within a few Km, we already have a direct comparison because the same amount of sun light fell on both systems during the test period.

It doesn't matter for how long we test it, the comparison is valid in terms of $ per kWHr , which is ALL that matters.


(hint, i have two packets of crisps to sell.  Packet A is 50grams and costs $0.20, Packet B is 25grams and costs $3.  Which one would you like to buy??  ;-)

Read my answer... This is what I did. But I guess reading more that one line and quoting it out context is all you can do.

I have ready you original answer, and like a lot of people who seem to think solar roadways are viable, you are missing the critical point, which is:

THE ABSOLUTE AMOUNT OF ENERGY PRODUCED BY A SOLAR ROADWAY IS NOT IMPORTANT!

The only thing that is important is:

THE COST OF THE ENERGY PRODUCED ON A $/kWHr BASIS.


So, you have a cloudy year and  your solar road way only makes 100kWhrs in total.  But a roof top installation of the same surface area (and vastly less cost) will produce roughly 200kWhrs.

So you have an amazingly "sunny" year and you solar road way makes a massive 100,000kWHrs in total.  But a roof top installation of the same surface area (and vastly less cost) will produce roughtly 200,000kWHrs.


In ALL cases, the higher efficiency (tilted panels, thinner, cleaner glass)  and lower installation costs means that the conventional roof top solar installation will have something like a 4x faster ROI than your solar roadway.  In our Capitalist economy, that is the only thing that matters!

Of course you didn't read all I wrote because I repeated more than once that I think those solar roads are bad ideas.
It's just that Dave spend almost half of this video saying that "they didn't beat the expectations" and that "it's all marketing"...
Well that first half of the video is just wrong. Sorry.

I'm a big fan of Dave and when I looked at the video the first time I was incredibly disappointed because he says that he took figures from neighbors at the same period of time... but ignored them to evaluate if the expectation are met or not.  :wtf:
(But now he added a comment in the video saying that it's less than 50%... thx Dave  8) )

But I also said that this doesn't change the fact that loosing 50% efficiency compared to panels on roofs plus the cost make this a bad idea. Unless you are near the equator because in that case you should have horizontal panels anyway, but in poor countries, putting high value panels on the ground is the best way to see them disappear... Conclusion: bad idea in all cases.

Another point that is not linked to the video is that panels on houses is not the panacea for many reasons: first the installation cost is not that low because for a given total surface you'll need many houses any many contractors... You'll also need an inverter per house... many elements will be duplicated.
Big farms of solar panels are better to my opinion (if it's not stealing land from agriculture).

You'd better use your roof to make hot water so you use less hydrocarbons when you take a shower.
And if you don't live in Sidney you may also use that to heat your house in winter and significantly reduce your C02 emissions.
 

Offline DanielS

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #65 on: May 15, 2015, 03:31:55 pm »
"Informed speculation is still speculation. In short, this guy is engaged in educated guessing on his blog, and that has ZERO WEIGHT."
Since SR is just an integrator project, the likelihood of SR discovering fundamentally new materials or components that might change the outcome of speculations based on off-the-shelf parts is abysmally low. The only thing that makes SR remotely feasible is the availability of relatively inexpensive off-the-shelf parts and materials, courtesy from the power, semiconductor and material industries that invests billions of dollars into it each year in their respective fields of interest.

I doubt SR would have a class-action on their hands if they were forced to admit the truth and publish the raw data for anyone to analyze. But their funding/play-money would likely dry up very quickly. For now though, they hide themselves behind the questionable excuse that off-the-shelf materials and components are somehow not representative of what they are working with.
 

Offline rsjsouza

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #66 on: May 16, 2015, 11:06:01 am »
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline abebarker

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #67 on: May 17, 2015, 01:04:15 am »
I, for one, think that solar roadways would be an excellent idea. I don't mean embedding PV cells in the surface, that is just foolishness.

Correct me if I am wrong but the very best possible solar collector, in theory, is a black body at 0.0K. It absorbs every wavelength of radiation. Although we can not have a roadway cooled to 0.0K or even 0.0C in practice, because of the condensation, we can cool it down in certain situations.

Knowing what the ideal solar collector is leads me onto another train of thought; How viable is it to pull the heat out of something to feed a heat engine? A common heat pump has a COP of 3-4. For every 1 unit of energy you put in you get 3-4 units of energy out.

The next question becomes; Is it possible to feed a heat engine with the output of a heat pump?
The answer is; Yes but it will not be a viable source of heat until the efficiency of the engine exceeds the inverse of the efficiency of the heat pump. Which is not easy because the efficiency of the engine increases with temperature difference where as the efficiency of the heat pump decreases with temperature difference (in the positive direction).

Solar roadways may become practical with the development of high efficiency, low differential heat engines, like the super critical waste heat engines or dissociable gas turbine engines.
 

Offline jwm_

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #68 on: May 17, 2015, 01:25:19 am »
Knowing what the ideal solar collector is leads me onto another train of thought; How viable is it to pull the heat out of something to feed a heat engine? A common heat pump has a COP of 3-4. For every 1 unit of energy you put in you get 3-4 units of energy out.

That's not what COP means, it means you can burn a btu of energy and pump 3-4 btus of heat energy with it. It does not produce any energy, just pumps it from one place to another while needing independent energy to make it run. All this energy has to already exist for it to be pumped around. And it is just heat that is pumped so it is not really useful energy unless what you want to do is heat something with it.

As to the amount of energy you can extract from a heat engine, it depends on the absolute difference in temperature between your hot and cold side. Solar heat engines work quite well, but in order to get the temperature differential needed to extract energy efficiently, they need parabolic mirrors to concentrate the suns rays to a single point. A black roadway may collect as much energy as a parabolic mirror of the same area, but it doesn't reach a temperature necessary for extracting any useful work from it.

Offline LabSpokane

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #69 on: May 17, 2015, 01:36:05 am »
The next question becomes; Is it possible to feed a heat engine with the output of a heat pump?
The answer is; Yes but it will not be a viable source of heat until the efficiency of the engine exceeds the inverse of the efficiency of the heat pump. Which is not easy because the efficiency of the engine increases with temperature difference where as the efficiency of the heat pump decreases with temperature difference (in the positive direction).

The answer is no.  The closest thing to what you seem to want is geothermal, where a small pump extracts enough energy at a high enough delta T to perform useful work.

Low grade heat used to power engines is difficult. 

The only technology that currently does so on a commercial basis is Organic Rankine Cycle, which is a closed circuit turbine that typically uses a refrigerant as the working fluid.  Net electric efficiencies are low at about 20-25% (highly dependent on delta T and the size of the system).  The upshot is that the maintenance costs are extremely low. 

Here's an overview of an ORC system:  http://www.epa.gov/chp/documents/meeting_100511_ronzello.pdf
« Last Edit: May 17, 2015, 01:40:51 am by LabSpokane »
 

Offline abebarker

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #70 on: May 17, 2015, 06:04:50 am »
That's not what COP means, it means you can burn a btu of energy and pump 3-4 btus of heat energy with it. It does not produce any energy, just pumps it from one place to another while needing independent energy to make it run. All this energy has to already exist for it to be pumped around. And it is just heat that is pumped so it is not really useful energy unless what you want to do is heat something with it.

A black roadway may collect as much energy as a parabolic mirror of the same area, but it doesn't reach a temperature necessary for extracting any useful work from it.

Yes. I agree. I will add that a heat pump not only moves those 3-4 units but it also compresses them into a smaller space i.e. it raises the temperature or increases the quality of the heat that is there.

The next question becomes; Is it possible to feed a heat engine with the output of a heat pump?
The answer is; Yes but it will not be a viable source of heat until the efficiency of the engine exceeds the inverse of the efficiency of the heat pump. Which is not easy because the efficiency of the engine increases with temperature difference where as the efficiency of the heat pump decreases with temperature difference (in the positive direction).

The answer is no.  The closest thing to what you seem to want is geothermal, where a small pump extracts enough energy at a high enough delta T to perform useful work.

Low grade heat used to power engines is difficult. 

The only technology that currently does so on a commercial basis is Organic Rankine Cycle, which is a closed circuit turbine that typically uses a refrigerant as the working fluid.  Net electric efficiencies are low at about 20-25% (highly dependent on delta T and the size of the system).  The upshot is that the maintenance costs are extremely low. 

Here's an overview of an ORC system:  http://www.epa.gov/chp/documents/meeting_100511_ronzello.pdf

The answer is yes. It doesn't have to supply the entire input, it may only supplement it. It may take more than one stage to raise the temperature enough. It could be used for regeneration.
Is it wise to do so? That remains to be seen.

Quote
Primarily designed for utilization of waste heat with low grade temperature sources, the charts for Organic Rankine Cycle can utilize temperatures below 212 F or 100 C and up to 180 C for standard refrigerants such as R134a or R245fa.
Quote
Efficiencies utilizing low grade temperatures can be three to 15 percent utilizing the ORC system

Quote
Brayton Cycle: Primarily designed for utilization of any heat with low to high grade temperature sources, the charts for the Brayton Cycle can utilize temperatures from 88 F or 31 C and over 550 C for CO2.
Quote
Brayton Cycle with CO2 has the potential to have an overall efficiency of up to and may exceed 45 percent.
http://www.infinityturbine.com/ORC/ORC_CO2_Performance_Publication.html
 

Offline EEVblog

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #71 on: May 17, 2015, 07:13:41 am »
Of course you didn't read all I wrote because I repeated more than once that I think those solar roads are bad ideas.
It's just that Dave spend almost half of this video saying that "they didn't beat the expectations" and that "it's all marketing"...
Well that first half of the video is just wrong. Sorry.

I'm a big fan of Dave and when I looked at the video the first time I was incredibly disappointed because he says that he took figures from neighbors at the same period of time... but ignored them to evaluate if the expectation are met or not.  :wtf:

Geeze, get over it  ::)
The ultimate goal of the video was to compare the output of the solar roadways to rooftop solar in the same area over exactly the same period. I didn't ignore those results!, I used them and got the final result of twice the output power of solar roadways. The rest of the video was essentially just filler to get to that point.
 

Offline gildasd

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #72 on: May 17, 2015, 09:15:25 am »
Another "lets not look at the details" article:
http://www.autoblog.com/2015/05/15/dutch-solaroad-outperforming-expectations/

Personally, I hate to see the cash evaporate into Solar Roadways when better usage could be easily be found with much higher environmental impact:
I am luky to study with some African students here in Antwerp, they get to pay the high fees due to their countries being in dire need of qualified port personnel.
(note, if you have IMO qualifications, young, single and need a well paid adventure, go to Africa)

In any case, we were talking about how in most of "black" Africa (their term), outside cities, that the lack of cheap after sundown light was a major source of lack of academic achievement.
To break it down, kids wake up do chores, go to school for 4/6 hours, do more chores till sundown.
Then they have time to study - if they have light.
If you are "rich" you can pay utilities, if not use a worn out Chinese generator on expensive black market fuel the last option is to study under a street light or sign.
Apparently, using candle light is awful, very hard to read modern print (compare a 2000's book with a 1930's book to get the idea) - and candles are expensive.

So, a good idea would be a small rootop PV, around 0.5m² to charge a small battery to sun a single 12watt CFD for 6 hours.
It would have to be a "ready to use package that could be anchored solidly, with a 5m extension with the bulb at the end.
THe materials would need to be plastic, fiber glass, and other valueless on the recycling market materials.

But, they told me, "don't give them away", sell them with for a token value WITH WARRANTY, so that users get a sense of propriety.

On the commercial side, they told me that there is a huge market for small PV (barn ventilation, insect destruction, fridges, well pumps, phone charging, WIFI points, cell towers etc) that don't need to be attached to a grid, be monitored closely or have to give a set result a day. Utilities suck there like here, but what here means someone overcharging you 30$, is a 48hours cut there, with attached dead livestock/crop.

One day, someone will sort out the right package, distribution, local manufacture (big tariffs in Africa) and earn megabucks.
While we will all be here saying "Aww shuckxs, shoulda thougta that".
I'm electronically illiterate
 

Offline Fungus

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #73 on: May 17, 2015, 10:39:47 am »
So, a good idea would be a small rootop PV, around 0.5m² to charge a small battery to sun a single 12watt CFD for 6 hours.
I'm sure there's at least half a dozen TED talks on this very subject.

(Either PV or a small hand-crank...)

 

Offline gildasd

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Re: EEVblog #743 – Solar Roadways Test Results
« Reply #74 on: May 17, 2015, 10:52:56 am »
So, a good idea would be a small rootop PV, around 0.5m² to charge a small battery to sun a single 12watt CFD for 6 hours.
I'm sure there's at least half a dozen TED talks on this very subject.
(Either PV or a small hand-crank...)
Problem is that it's talk.
I'm electronically illiterate
 


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