[Freedombox-discuss] Routing around nationwide and international Internet blocks

[Eugen Leitl]

On Mon, Feb 28, 2011 at 05:32:20PM +0100, Michael Blizek wrote:

> > I don't know where you live, but there is a lot of
> > grid-tied PV installations around here.
> 
> grid-tied PV is most often unable to provide power, if the grid is off. There
> are ways to do this, but they require more equipment: (1) an inverter which
> is able to do this and (2) a battery

Part of the expense of a grid-tied inverter is that it separates
from the main grid when it goes down, and goes insular on 
quartz-stabilized mode, and resyncs when grid goes back online.

Battery yes, but only during the night. A reasonably inexpensive
UPS should be able to buffer an embedded over night.

For our purposes you'd go minimal insular, battery-backed.
 
> > > remaining batteries and a handful of generators, electronic
> > > communications would be essentially gone no matter what
> > > kind of box we build.
> > 
> > You could run an Android based Serval node or long-range 
> > WiFi node on a 15-20 W PV panel (99 USD, sans battery) 
> > indefinitely. Lighting up a fiber for only slightly more.
> 
> This IMHO very optimistic. It might be the case near the equator, but it is

That's possible, as nominal capacity is typically measured in
absurdly optimistic Wp.

> definitely wrong in central europe. Here you need about 30-70W PV pannels per
> watt your devices take - at least if you want to power your network in the
> winter season, too. You also need a battery and charging electronics.

Affordable panels do come with the charger these days

http://www.amazon.de/gp/product/B002GYRZ88/
http://www.amazon.de/Solarpanel-Solar-Ladeset-Laderegler-Batterieklemmen-DC-Stecker/dp/B003ZZORMO/

Solar-rated lead-acid gel batteries are admittedly
a bit pricey. The built-in battery of a cell phone
will need some thermal management, as direct sunlight
will likely fry it quite soon.
 
> A tiny WLAN router might take is low as maybe 2 W. But you may want more than
> one. I guess powering a fiber will take a lot more.

There are fanless L2 switches which take 2 SFP slots.
Both SFP and SFP+ transceivers themselves take less
than 1 W. Driving GBit ports would take more, though
some green switches can shut down unused ports.

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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