If you built a laptop where the entire lid was a solar panel, would it 
generate anywhere near enough power to run the laptop?

Would it even generate enough power to recharge the battery in a 
reasonable amount of time?

(For reasons unknown, Dell sent me a free gift today: A solar charger. 
Who knows, it may even be useful...)

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> If you built a laptop where the entire lid was a solar panel, would it 
> generate anywhere near enough power to run the laptop?

So long as you're happy to use it lying down :-)

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scott wrote:
>> If you built a laptop where the entire lid was a solar panel, would it 
>> generate anywhere near enough power to run the laptop?
> 
> So long as you're happy to use it lying down :-)

I was thinking more that while the lid is shut, it could be soaking up 
some rays and recharging the battery.

The fatal flaw in this plan, of couse, is that most normal /homo 
sapiens/ would put the laptop back in its bag...

I'm just curios as to whether a solar panel that size can generate 
enough current to be useful, that's all.

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> I'm just curios as to whether a solar panel that size can generate enough 
> current to be useful, that's all.

About 100W / m^2 *roughly* from what I remember.  My (big) laptop is 0.1m^2, 
so 10W.  Enough to charge it slowly (my AC adapter is 90W IIRC).

But you would have to leave it in direct sunlight, don't most laptop specs 
say not to leave it in direct sunlight?

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>> I'm just curios as to whether a solar panel that size can generate 
>> enough current to be useful, that's all.
> 
> About 100W / m^2 *roughly* from what I remember.  My (big) laptop is 
> 0.1m^2, so 10W.  Enough to charge it slowly (my AC adapter is 90W IIRC).
> 
> But you would have to leave it in direct sunlight, don't most laptop 
> specs say not to leave it in direct sunlight?

...so in other words, *no*.

In fact, my old laptop idles at 20W, which is *still* too much. At best, 
the solar panel would double the battery life. (If it weren't for the 
minor detail that the battery is cluser-****ed anyway...)

Then again, with that old laptop, I start wondering if you could use it 
to run a small steam engine connected to a generater. The thing gets hot 
enough! :-P

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>> I'm just curios as to whether a solar panel that size can generate 
>> enough current to be useful, that's all.
> 
> About 100W / m^2 *roughly* from what I remember.

Check it out:

http://blog.orphi.me.uk/about/power

You'll notice that I mainly measured high-power devices anyway, but still...

(I love the way turning my PC on requires 50% more power than playing a 
3D-intensive computer game...)

Now then, what do you suppose the total area of my roof is? (Are solar 
panels even waterproof?!) With all that area, you could generate... 
almost 1 kW. On a sunny day.

So, let's see... *almost* enough power to run half a vacuum cleaner.

I wonder if it would make a difference living in the Sahara?

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> ...so in other words, *no*.

Better to put solar panels on your roof and then just use the standard 
charger.

> Then again, with that old laptop, I start wondering if you could use it to 
> run a small steam engine connected to a generater. The thing gets hot 
> enough! :-P

In terms of generating power, bigger is always more efficient, something 
per-laptop is likely never to work.  Just face it, CPUs currently are just 
electrical heaters that happen to do some calculations at the same time.

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> Now then, what do you suppose the total area of my roof is? (Are solar 
> panels even waterproof?!)

Of course they are waterproof, they are also lots-of-snow and 
big-lumps-of-ice proof.  Otherwise people wouldn't put them on their roof. 
FWIW there are different ratings depending on how much snow-load you want to 
support.

> With all that area, you could generate... almost 1 kW. On a sunny day.

A house down the road from us just got them installed, seems like they had a 
grid of 6x5 panels put on their roof, they look about a m^2 each, so 3 kW. 
It seems quite popular around here (southern Germany), especially in the 
more rural areas.

> So, let's see... *almost* enough power to run half a vacuum cleaner.

Sure, but you don't run that very often.  Usually the power company will buy 
back any excess power you don't use (which I suspect is most of the time 
when it's sunny), and of course if you need more you can buy it from them 
too.  I wouldn't be surprised if you got a negative power bill overall 
without too many panels.

> I wonder if it would make a difference living in the Sahara?

The main difference would be due to how many hours of sunlight you got on 
average each day, somewhere where it rains the whole time is not likely a 
good idea.

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> Just face it, CPUs currently are 
> just electrical heaters that happen to do some calculations at the same 
> time.

LOL. I'm sure this says something deep about quantum thermodynamics.

Hmm, I wonder... does the human brain heat up significantly when you 
think harder?

[Before anybody else points this out, I know it heats up *measurably*. 
I'm wondering if it heats up *significantly*...]

OTOH, the brain is inherantly decentralised. It relies on ludicrous 
numbers of independent elements operating in a massively parallel 
mannar. A laptop works on one specific element peddaling along in serial 
as fast as possible.

Say, whatever happened to ANN chips?

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>> Now then, what do you suppose the total area of my roof is? (Are solar 
>> panels even waterproof?!)
> 
> Of course they are waterproof, they are also lots-of-snow and 
> big-lumps-of-ice proof.  Otherwise people wouldn't put them on their 
> roof. FWIW there are different ratings depending on how much snow-load 
> you want to support.

Wait - I thought that was still science fiction? You mean people 
somewhere *actually do this* now??

>> So, let's see... *almost* enough power to run half a vacuum cleaner.
> 
> Sure, but you don't run that very often.

Not in *this* house. ;-) The kettle gets far more use... oh, wait...

> Usually the power company will 
> buy back any excess power you don't use (which I suspect is most of the 
> time when it's sunny), and of course if you need more you can buy it 
> from them too.  I wouldn't be surprised if you got a negative power bill 
> overall without too many panels.

I rather suspect not. Turn on the kettle, the toaster and the microwave 
oven at the same time (not implausible) and you're now sucking down 
double-digit kW values. Plus all those things like the freezer which you 
never, ever turn off. I doubt you can power an entire building full of 
stuff and show a positive net balance for more than an hour or so a day.

Unless you live in the mediterranian, perhaps. (Remember, I live in 
Britain, a nation famous for its rain.)

>> I wonder if it would make a difference living in the Sahara?
> 
> The main difference would be due to how many hours of sunlight you got 
> on average each day, somewhere where it rains the whole time is not 
> likely a good idea.

Actually, I guess the *main* difference would be that if you live in the 
Sahara, you don't give a **** about electricity, but you urgently need 
to find a crapload of water real soon now...

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They make a flexible solar panel that
puts out about 50 Watts, open it's 54" x 32",
folded up it's about the size of a text book.
It'll run a laptop pretty easy.

There's no real problem with putting solar
panels on houses in temperate areas, (they're
waterproof), it just means you need more panels, 
so it increases the cost. Cost is the big downside
of solar electric panels, it costs more than just
buying the juice in the first place. There's quite
a few places working on making it cheaper with
limited success.

Solar concentrators rely on technology that can
be much cheaper, it's just mirrors. Evacuated
solar tubes can produce scalding hot water, or
you can build simpler solar hot water heaters 
DIY at very low cost. The heat can then be
directly used for heat, thus cutting out the 
90+ percent loss of turning sunlight to electricity
and then turning electricity to heat. The downside
is maintenance of the anti-freeze.

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> Wait - I thought that was still science fiction? You mean people somewhere 
> *actually do this* now??

The company I work for made 600 MW of solar panels in 2006 (that's the 
latest figures I could find), I'm sure it's gone up lots since then.  Drive 
around any village around here and you're bound to see at least a few houses 
or barns covered in them.

> I rather suspect not. Turn on the kettle, the toaster and the microwave 
> oven at the same time (not implausible) and you're now sucking down 
> double-digit kW values.

Sure, but what's the average power over a longer period of time?  You can 
easily calculate this from your power bill.  IIRC for me it was around 300W, 
and yes I have a fridge, freezer, TV, computer etc.  Even fridges and 
freezers are not actually on continuously.

If you assume I'll get 2 hours a day sunlight on average (this is a big 
underestimate, especially as the panels generate a reduced level of power 
even when it's cloudy), that means I would need 3600W of solar panels, or an 
area roughly 6x6 metres.  Doesn't seem that outrageous.

> Actually, I guess the *main* difference would be that if you live in the 
> Sahara, you don't give a **** about electricity, but you urgently need to 
> find a crapload of water real soon now...

Funny, when I was in the Sahara desert, the villages there had a perfectly 
fine water supply, also ATM machines, mobile phone coverage, etc.

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>> Wait - I thought that was still science fiction? You mean people 
>> somewhere *actually do this* now??
> 
> The company I work for made 600 MW of solar panels in 2006 (that's the 
> latest figures I could find), I'm sure it's gone up lots since then.  
> Drive around any village around here and you're bound to see at least a 
> few houses or barns covered in them.

Mmm, interesting. I've never seen that. (Again, presumably because I 
live in England.)

>> Actually, I guess the *main* difference would be that if you live in 
>> the Sahara, you don't give a **** about electricity, but you urgently 
>> need to find a crapload of water real soon now...
> 
> Funny, when I was in the Sahara desert, the villages there had a 
> perfectly fine water supply, also ATM machines, mobile phone coverage, etc.

Heh. And here I was thinking the only thing in a desert is sand...

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Invisible schrieb:
> If you built a laptop where the entire lid was a solar panel, would it 
> generate anywhere near enough power to run the laptop?

At first glance I'd say, "might be".

If you ever took to the outside with a magnifiying glass and a piece of 
paper on a summer day, you probably know how much power there is in 
sunlight, when concentrated. So as a first rought guesstimate, imagine a 
magnifying glass the size of a laptop lid, concentrating solar energy on 
something as big as a CPU die.

If that would produce as much heat as a running CPU, then we're at least 
talking about the same orders of magnitude.

Upon closer inspection of the problem, this article: 
http://home.howstuffworks.com/home-improvement/energy-efficiency/question418.htm 
states that with cheapo solar cells, you can harvest no more than about 
.045 W per square inch; the article then goes on presuming a figure of 
.070 W, probably assuming the use of higher-quality cells.

With a laptop about as large as an A4 sheet of paper - about 100 square 
inch - that would give you... 7 Watts. Not /quite/ the order of 
magnitude you'd probably need...

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clipka wrote:

> With a laptop about as large as an A4 sheet of paper - about 100 square 
> inch - that would give you... 7 Watts. Not /quite/ the order of 
> magnitude you'd probably need...

Hmm. What's the TDP of a typical CPU? About 150W? Oh dear...

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Invisible schrieb:
> Then again, with that old laptop, I start wondering if you could use it 
> to run a small steam engine connected to a generater. The thing gets hot 
> enough! :-P

Heh, someone called my name?!

Oh boy, I've definitely been doing too much research for that locomotive 
model lately, reading stuff like this for instance:

http://www.the-nerds.org/Steam-Car-Day.html

Well, at least by now I know what /some/ of the greebly stuff on a 
locomotive is actually good for...

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clipka wrote:
> Invisible schrieb:

> With a laptop about as large as an A4 sheet of paper - about 100 square 
> inch - that would give you... 7 Watts. Not /quite/ the order of 
> magnitude you'd probably need...

That's nearly enough to power a low-power laptop.
The OLPC (one laptop per child) scheme says their laptops are limited to 
use 15 Watts
http://laptop.org/en/laptop/hardware/specs.shtml

So 7 watts is nearly there - you could fit a fold-out panel on the back 
of the laptop or do something cunning with mirrors / fresnel lenses to 
focus more sun on the panel.

I believe my mini ITX server uses 10 - 20 W depending on load and it's a 
1 Ghz machine with a fullsize hard drive but no display and it's not the 
most efficient design out there.

On the other hand "my" blade centre with 12 quad core servers in it uses 
1700 W which is more than 3x my house's average consumption.

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Invisible schrieb:

> Hmm, I wonder... does the human brain heat up significantly when you 
> think harder?

No, because the efficient adaptive cooling system makes sure it doesn't :-P

But yes, the human brain makes for a good deal of energy consumption in 
the organism. And consumption does vary, so heat output will, too.

I'm particularly slim by build, despite virtually living on sweet stuff. 
An acquaintance suggested that in order to start gaining weight, I 
should actually do /more/ bodily exercising (especially endurance 
training; I'm admittedly quite lazy in that respect). Why? Because 
endurance training is a perfect "no-brainer".

In other words: I'm probably this slim because I think too much...

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>> Hmm, I wonder... does the human brain heat up significantly when you 
>> think harder?
> 
> No, because the efficient adaptive cooling system makes sure it doesn't :-P
> 
> But yes, the human brain makes for a good deal of energy consumption in 
> the organism. And consumption does vary, so heat output will, too.

One thing a lot of people don't seem to realise is that the brain does 
*other stuff* besides thinking...

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Invisible schrieb:

> (I love the way turning my PC on requires 50% more power than playing a 
> 3D-intensive computer game...)

Yeah, the turn-on is always the hardest part :-P

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Invisible schrieb:

>> Of course they are waterproof, they are also lots-of-snow and 
>> big-lumps-of-ice proof.  Otherwise people wouldn't put them on their 
>> roof. FWIW there are different ratings depending on how much snow-load 
>> you want to support.
> 
> Wait - I thought that was still science fiction? You mean people 
> somewhere *actually do this* now??

Definitely so. Seen this a /lot/ in south-eastern Germany, too. And the 
house I grew up in (and which my parents sold some months ago) has just 
been equipped with solar panels, too (not sure whether the photovoltaic 
or water-heating type) - even despite it being on a hillside facing 
north, in a particularly rainy valley of a particularly rainy area of 
western Germany.

It's really gearing up these days in Germany. I guess the development of 
oil prices in the last 1-2 years are taking effect: People started 
getting aware in a very practical way that we'll not be able to live on 
fossil fuels forever.

It's still not competitive with grid power /yet/, but the government 
does a lot here to support such investments, so for the end user it does 
pay off. All the more if you figure in future oil price rises, which 
people in Germany have started to do. It's now actually considered a 
financial investment over here, not just an ecological one.

And I just read that for instance in Hawaii, solar power is now already 
cheaper than ordinary grid power.

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Invisible schrieb:
> One thing a lot of people don't seem to realise is that the brain does 
> *other stuff* besides thinking...

Sure - but given that evolution added(!) some 200% more brain mass to 
Homo Sapiens over his ancestors and relatives, apparently /for/ thinking 
(and speaking, which appears to be a closely related task), I guess it 
is reasonable to assume that the /majority/ of our brain's capacity is 
devoted on it.

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Invisible schrieb:

> Hmm. What's the TDP of a typical CPU? About 150W? Oh dear...

For a laptop CPU, you're going for a good deal less.

Also note that's the /maximum/ rating.

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clipka wrote:
> And I just read that for instance in Hawaii, solar power is now already 
> cheaper than ordinary grid power.

The big kicker is installation/material cost.  Last I checked, at normal 
usage, with both electric and water heating done or supplemented by 
solar, it'd take like 20 years to recoup the price...but it *would* be 
regained.

--
Tim Cook
http://empyrean.freesitespace.net

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On 21-9-2009 15:16, clipka wrote:
> Invisible schrieb:
> 
>> (I love the way turning my PC on requires 50% more power than playing 
>> a 3D-intensive computer game...)
> 
> Yeah, the turn-on is always the hardest part :-P

All those electron that have to get up to speed. When they are moving it 
costs less to keep them at speed. Or maybe not.

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On 21-9-2009 15:10, Verm wrote:
> clipka wrote:
>> Invisible schrieb:
> 
>> With a laptop about as large as an A4 sheet of paper - about 100 
>> square inch - that would give you... 7 Watts. Not /quite/ the order of 
>> magnitude you'd probably need...
> 
> That's nearly enough to power a low-power laptop.
> The OLPC (one laptop per child) scheme says their laptops are limited to 
> use 15 Watts
> http://laptop.org/en/laptop/hardware/specs.shtml

That is what they are limited to. IIRC the goal was about 2W as you can 
generate that as a human being of child like proportions. Might be in 
this video 
http://www.ted.com/talks/nicholas_negroponte_on_one_laptop_per_child_two_years_on.html



> So 7 watts is nearly there - you could fit a fold-out panel on the back 
> of the laptop or do something cunning with mirrors / fresnel lenses to 
> focus more sun on the panel.
> 
> I believe my mini ITX server uses 10 - 20 W depending on load and it's a 
> 1 Ghz machine with a fullsize hard drive but no display and it's not the 
> most efficient design out there.
> 
> On the other hand "my" blade centre with 12 quad core servers in it uses 
> 1700 W which is more than 3x my house's average consumption.

There is that story about, I think, Shell that they build a new building 
with a giant heater for the winter, just when everything was nearly 
finished they brought in a supercomputer that needed a giant cooling 
system. A bit more communication would have saved a lot of money.

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Invisible wrote:
> If you built a laptop where the entire lid was a solar panel, would it 
> generate anywhere near enough power to run the laptop?
> 
> Would it even generate enough power to recharge the battery in a 
> reasonable amount of time?
> 
> (For reasons unknown, Dell sent me a free gift today: A solar charger. 
> Who knows, it may even be useful...)

Nope. I looked into it, even the EeePC line takes enough power to 
operate that you would need one of those folding panel things they now 
make, which unfolds to about 6'x4', if I remember right. Or, more 
specifically, you could probably manage it with like 5'x3', or 
something, but they don't make ones that size. One the size of the back 
of a laptop would only net you probably 30-40% (guessing) of the power 
needed, and that is without peripherals of any kind.

Recharging is a little less of an issue, but its going to take time to 
do it, and probably longer than a wall plug.

-- 
void main () {
   If Schrödingers_cat is alive or version > 98 {
     if version = "Vista" {
       call slow_by_half();
       call DRM_everything();
     }
     call functional_code();
   }
   else
     call crash_windows();
}

<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models, 
3D Content, and 3D Software at DAZ3D!</A>

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andrel wrote:
> There is that story about, I think, Shell that they build a new building 
> with a giant heater for the winter, just when everything was nearly 
> finished they brought in a supercomputer that needed a giant cooling 
> system. A bit more communication would have saved a lot of money.

On the other hand at my site they did think about that, so they 
integrated the cooling of the machine rooms with the heating of the rest 
of the site....
10 years (or so) later our machines are a lot more efficient and create 
less heat so they no longer provide enough to warm the site, so a new 
gass powered heating system was needed.

I believe the "new" UK ATC centre on the south coast has the same 
problem - but they've not yet installed any more heating. (they switched 
from huge CRT displays to beautiful flatscreens that don't get as toasty)

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> I believe the "new" UK ATC centre on the south coast has the same 
> problem - but they've not yet installed any more heating. (they switched 
> from huge CRT displays to beautiful flatscreens that don't get as toasty)

Same happened at University - building had been planned to be full or CRT 
heaters, only everything got replaced by LCDs so we all froze.  At least 
that's what they claimed...

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Invisible wrote:
> 
> In fact, my old laptop idles at 20W, which is *still* too much. At best,
> the solar panel would double the battery life. (If it weren't for the
> minor detail that the battery is cluser-****ed anyway...)
> 

My old laptop runs ~35W on full power, according to ACPI. You just
happen to have a cheap-series powerhog ;).

-Aero

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