hand powered linux box

[Duane Attaway]

On Tue, 14 Dec 2004, djgoku wrote:

> Reading on some solar panels that are out there I found these since my
> computer is using around 300 watts with monitor. I'm kinda confused on
> what Approx. Watt-Hrs / Day = 1200 - 1500. I know you just can't run
> your computer off these panels but you would need a battery of some
> sort for the panels to charge. But does that mean that it charges 1200
> -1500 watts/ a day so you would need a couple 700 watt batties or?
> Most car batteries are like 300-700 watts no? not crank just the
> storage part if that is what it is called.
>
> http://www.icpsolar.com/ssfamille.php3?id_rubrique=56

Since this stuff isn't at Walmart yet, the possibilities are only limited 
by imagination...

My marine battery will power my computer and the stuff on my desk for 
about five hours, perhaps longer.  If I were going to rely on solar power, 
I'd want at least two days of not having to worry.  I could be pendantic 
about math calculations and measurements and push things to their physical 
limits, but its never exact in the real world.  So, let's make that 10 
125Ah marine batteries and call it two days.

Now, we could attatch the solar cells directly to the batteries.  There's 
only one problem though.  When the batteries reach full charge, the cells 
will gas the water right out of them.  Then the batteries are no good, 
except for boat anchors.  We need a charge regulator that combines the 
output of the solar cells and maintains the batteries.  The charge 
regulator can have its own inverter and switchgear so it can interface 
directly with the AC mains.  Its all up to you what to get.

What do I use?  I use a cheap APC power supply that toasted its batteries 
in the usual 2 years.  When I get solar panels, I'm going to install a DC 
to DC converter to isolate the panels from the batteries and maintain the 
charge.  That's because UPS supplies usually have the battery tied hot to 
the AC mains and extending the circuit out to the roof.  We don't want 
corrosion of the panels or a fire hazard, so isolation is a good thing.

How many solar panels?  I'd go many as possible and see about getting a 
peaking inverter that will take excess power and put it directly into your 
AC mains.  That circuit will require monitoring of the utility mains in 
case there is a blackout and linemen are working in your back yard.  We 
wouldn't want to energize the pole in your backyard when the guy is 
crimping on new connectors.

Oh, I can push an average of 200 watts of power from my exercise bike.  A 
hamster can put out enough power to light a LED.  Must not forget all 
sources of power that can run our computers!

http://www.otherpower.com/hamster.html
http://www.otherpower.com/otherpower_experiments.html

-=Duane
http://dattaway.org