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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