Linux services without mains power (Tectonic) [LWN.net]

Stevan Lockhart explains how he set up an off-grid Linux-powered home and business in Scotland. "Originally from Cape Town, Stevan Lockhart now lives in the north west of Scotland in a house that is off the electricity grid. Using a wind generator, some solar panels and free and open source software he and his wife both run their businesses off just 20W of power. Here Stevan explains the software and hardware decisions that made this lifestyle possible."

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20W refers to one server, not the whole lifestyle!

Posted Mar 13, 2009 0:45 UTC (Fri) by xoddam (subscriber, #2322) [Link]

The 20W is what a single power brick (supplying both a router and a server) draws from the 230V supply from an inverter. With their lifestyle including CF lights, a cordless phone, a stereo, and a second higher-power inverter to supply the demands of a vacuum cleaner and a microwave oven, I think the total electric power requirement must be rather more! And I can imagine in that climate they must also generate thousands of watts of thermal power using gas or fuel wood.

I see an interesting opportunity in providing an easy way to replace numerous power bricks with a combined DC power supply. Within two metres of me there are eight of them. In the off-grid case it would make sense to run the always-on services with DC directly from the battery bank instead of via an inverter and rectifier.

20W refers to one server, not the whole lifestyle!

Posted Mar 13, 2009 1:06 UTC (Fri) by endecotp (guest, #36428) [Link]

> easy way to replace numerous power bricks with a combined DC power supply

I have a "squid" powering some of the junk on my desk; you've probably seen the mains version, but there are DC ones around: (http://www.kvmtools.us/product_info.php?products_id=16918 - no photo, unfortunately). But it's surprising how many different voltages there are, e.g. 5v, 6v, 12v, 15v, and different plugs, and you have to be careful about the different input capacitors that different devices have: if box A has a small input cap and you plug in box B with its large input cap on the same squid, A will suffer a brown-out. (The USB spec specifies limits on inrush currents to avoid this, IIRC.)

Anyway, re the article: his "off grid low power" server is very similar to my desktop machine, and my "on grid low power" server is an NSLU2...

20W refers to one server, not the whole lifestyle!

Posted Mar 13, 2009 12:03 UTC (Fri) by stevan (subscriber, #4342) [Link]

Yes, you are correct. The article is about the IT rather than the power supply, although it seems a lot of people are interested in how we operate off the electrical grid. My intention was to show that you could run scalable systems suitable for running a business on not-a-lot of both power and hardware, and to suggest that taking a slightly different path for these often helps.

You could run off the battery to save a little of the inefficiency of the brick, but there are issues with that, such as the fact that the battery bank voltage does fluctuate depending on whether it is under charge or load, and as I suggest it's easier the way we do it.

Stevan

Linux services without mains power (Tectonic)

Posted Mar 13, 2009 9:26 UTC (Fri) by muwlgr (guest, #35359) [Link]

The most interesting would be to know about various collateral topics of this off-grid living, like :
how much was invested initially in wind generator, solar panels, inverters ;
how much kWh is generated and consumed per day/week/month/year ;
what is the local rate for grid electricity kWh, and how soon it is expected to reach a break-even point ;
how the house is heated in colder seasons, and how perishable food is kept in warmer seasons ;
what other external factors create the most dependency for author's survival ?
And so on.

Linux services without mains power (Tectonic)

Posted Mar 13, 2009 12:19 UTC (Fri) by stevan (subscriber, #4342) [Link]

As I said on the Tectonic site, it'll be good to answer those questions in some forum, but part of the opportunity is to think differently from convention, both using the choice offered by Free Software and because we're not really doing this for pure economic drives, or to be honest, purely out of "green" motives. We were faced with a steep bill for getting grid electricity to the house, when I'd always wanted (like many) to try my hand at alternative electrical generation. So far we've spent a fraction of the cost of getting grid power here, so we're quids-in. The cost per kWh therefore doesn't interest us much.

Mostly, though, my renewable power abilities, I think, lag my IT skills drastically, so I'm more comfortable about things on which I'm more knowledgeable. This comment suggests I should recognise that people are interested in the whole picture.

I really did not expect the interest in the supply-side to be as great, I must admit, so I'll look at ways of answering those questions. With the recent BBC series on Highland life by Monty Hall, based in Applecross, 70-odd miles south of us, it's inevitable that there will be heightened interest in these practicalities.

Stevan

Linux services without mains power (Tectonic)

Posted Mar 14, 2009 18:55 UTC (Sat) by Soruk (guest, #2722) [Link]

Thanks for the heads-up - as I write both episodes 1 and 2 are still on iPlayer.