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 ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE _______________________________________________ Freedombox-discuss mailing list [email protected] http://lists.alioth.debian.org/mailman/listinfo/freedombox-discuss
