Ok 2-3 years, should be fairly enought for every project i’d guess. http://en.wikipedia.org/wiki/Rechargeable_battery#Table_of_rechargeable_battery_technologies

I was more looking into a proove of concept mesh network of small and cheap nodes.

hmm on vacation and thinking about wireless mesh networks not good

The capacitor you describe requires a “supercap” to store sufficient energy. These are not that much more economical than LiPo’s. I’m not sure LiPo batteries will last only 1..2 years in this context, since they are being charged/discharged at fairly low rates.

Nice link about Radish – thanks.

Note that harvesting solar energy indoor is hard. The levels of light are orders of magnitude less than out under the sun. See http://www.eevblog.com/2009/12/04/eevblog-48-solar-power-hope/ for an entertaining video about this.

I’d guess you plan on taking on your “self-sustaining solar node” again. (http://news.jeelabs.org/2009/07/03/mystery-jeenode/)

I’d love to see more of this coming.

just thinking a few steps further. Thought I do not know much about capacitors, but wouldn’t a capacitor as energy reservoir make this node even last over years. I mean even a LIPO cell will reach it’s end of it’s lifetime in what 1-2 year(s)?

like this one: (http://code.google.com/intl/de-DE/apis/gdata/articles/radish.html)

This would turn the node into a real self-sustaining node, there is no maintenance required (f.e. changing the LIPO cell once a year). Once the node is able to update itself via wireless (which is just a matter of time if not already solved), such a node could even run for 10+ years.