Monday, November 29 2021

Paradoxes, Power and Performance

Some thoughts on changes in our off-grid supply and demand over the years.

It's hard to believe that we have lived off the electricity grid for well over 14 years now.   I had been thinking of some of the changes we've seen in those 14 years. 

Generally speaking, we run whatever we need to run on electricity.  We used to add "except for things that generate heat", but that's not strictly true, as we can and do use an electric toastie maker, waffle maker, and a small kettle. But as a general rule, we are cautious about only using such high energy demanding appliances when we know the wind or sun is strong enough. That includes the whole of summer, when we can rely on the sun. For heat-generating appliances, a kilowatt is a kilowatt. But what about other things running on electricity?

When we first moved here permanently, we used fluorescent light bulbs, which, although they took a while to produce full light, were much more power efficient than incandescent bulbs.  We still needed quite a lot of power for them, though, and lighting was a major consumer of power.  We started making the move to LED lights pretty much as soon as they became available, and then fully when they became more affordable.  LED lights have meant a dramatic decrease in power consumption. But along with that decrease, we have also increased the number of lights we have, making life feel more pleasant, especially in winter. Helen used to have a 20 watt bulb in her old dye shed.  That old shed is now her wool store, and as she wants her customers to be able to see the wool better, we have added two racks of spotlights. These, which really light up the place brightly, use just 32w of power.  So while we have much better lighting, we actually use more power.  This example is not a major drain on our electricity storage, though, because the wool store is mainly used in the brighter months, when customers are about, while energy reserves are lowest in the dark winter months, when there are fewer visitors.

This is an example, of course, of Jevons Paradox, that when technology increases the efficiency with which a resource is used, the rate of consumption increases because of increased demand.  The example is cited of more fuel-efficient cars resulting in higher fossil fuel consumption, because people use their cars more.

I am not too worried about the effects of Jevons Paradox on our general usage of electricity, though, and that's because it is not universally true.  That could be because of a certain discipline on our part, but more likely just that we use electricity to meet our needs and little more.

For example, we run our own IT services, so we have a server here at home.  This has always run Linux. The differences between a 2009 article I wrote for the now-defunct Tectonic magazine and today are marked.  Here, the difference 12 years makes is much more marked, as processors and disks for general use have become much more power efficient.  In that article, our server used 18 watts of power and the router 10.  These days, our server is a Raspberry Pi with SSD disks, and uses about 6w of power. The router uses about 6 as well.  Our laptops nowadays have AMD Ryzen CPUs.  The best we could do regarding electricity consumption in 2009 was about 18-24w per laptop.  These days, our laptops are many times more powerful, allowing us to do things, like video processing, we could not have contemplated back then.  Yet my laptop uses less than 5w of power when idling and when working hard, for example, short periods of processing video, will rise into the 20s. But in general our technology is an overall power saving.  Again, we could have chosen equipment that is more powerful, but what we have is perfectly adequate - more than enough - for our needs.

As key consumers, such as lighting and technology, have become more manageable, so other aspects have become more do-able.  One important aspect for a more convenient life was a fridge.  When we used our house just for holidays, and living here permanently seemed a distant dream, we simply had a caravan fridge. This could use 12v battery power, 230v mains power or gas. In all three cases, it used heat to drive refrigerant around the system, and was dreadfully inefficient. For practical purposes, we used gas to power this, as the electricity demand, well over 100w for about 18 hours in the day, was simply too much. We started looking at conventional fridges and found a small one though bigger than the caravan fridge, that used just 65w of power.  In practice, it used about 45-50w, measured at the wall, but like all motors, gave the inverter a real jolt of demand when starting. We solved that by using a better capacity inverter. Oddly, this was a very cheap no-name fridge.  We found that all the more expensive, branded fridges, used much more power, though labelled as more energy efficient. I've not been able to work that one out. These days, again, buying at the cheaper end of the market, we have a much larger, double door fridge-freezer that adds hugely to the convenience of life.  This draws a theoretical 85w of power, but in practice only around 50w.  It's now hard to imagine life depending on that old caravan fridge, the only memory of which is a burn mark on the wall from the gas burner. This example does highlight an aspect of off-grid living: when one goes into a shop for a new appliance, the first thing we ask is "What is the wattage?" Only then do other factors come into play.

Our supply side has, to a large extent, improved.  Our third set of solar panels, and the first set to make a significant contribution to our power supply, was a pair of 200w panels, and we were delighted that their price had come down such an extent that we paid just £800 for the pair.  Fast-forward a few years, and we realised just how much power the sun provides even at our latitude, so we based our power supply on solar.  This time we bought four panels, of 250w each, for, yes, the same total cost, £800.  I have not checked panel prices recently, but fear that recent political changes will have made them more expensive.

Given these changes, we have let ourselves go a little. Those solar panels mean that, for at least 9 months of the year, we have few or no concerns about the state of the battery bank.  So we are happy to use more power.  We have a toastie maker now, and a waffle maker, and we have always had slow cookers. We also use an electric breadmaker in summer.  In winter, if there is a period of plentiful wind (if???), we use the slow cooker, and only use the toastie or waffle maker-type appliances when we know the batteries are topped up. We use other kitchen appliances pretty much on demand, such as mixers, blitzers and so on.

We are much less aware of being power-challenged, as one might say, these days, except for the two deepest winter months, when we depend almost entirely on our small wind charger, and may have to resort to using a generator to top up the battery bank. As time goes on, I may look at improving the situation for those two months, which may increase the overall supply, and we may end up using more electricity, for example, for cooking.

Addendum:  I meant to include one aspect of off-grid life about which people often ask; washing.  Until this year, we have used a small caravan-style twin-tub washing machine for this.  Wash day originally meant filling the tub, passing the washing to the bath for rinsing after a spin, then spinning again.  I didn't mind doing this too much, as it's a necessary chore.  We later found non-detergent washing liquid that meant we did not have to do the rinsing part, and that streamlined things.  The biggest issue was lugging the washing machine to a frame over the bath, for ease of transfer and to allow drainage, then lugging it back to its spot after the event. The saving grace of this relatively labour intensive process was the power consumption - about 250w for the washing and about 150w for the spinning.  Why this style twin-tub? Well, most washing machines include heating elements, and their electronics won't function unless the element works too. This could be up to 2 or 3 kw of power, and that's not possible.

This year, after years of saying "we must get around to replacing the bathroom units", we finally stepped up and did a full revamp of the 1950s bathroom, taking out the ancient enamelled steel bath, which will become a tattie patch or flower bed in the garden, and the cracked old toilet and basin. We discovered the joys of houses like ours, where no two walls are parallel, and which made fitting a shower unit, which requires precision for the door units to operate correctly, an interesting job. At the same time, I re-did all the old imperial pipework, and ran additional hot and cold pipes to a now-open corner of the bathroom, where the bathroom taps used to be. This was going to be a permanent home for the old twin-tub, but I wondered if we could find a washing machine that was less labour intensive.  Sure enough, we managed to find such a thing.  It's a single-tub top loader, and is fully automatic.  You add as much hot water as you like, and the machine then tops it up to the required mark with cold. Forty minutes later, the machine beeps and you have clean, well-spun clothing.  This has dramatically reduced the work of wash day. And it uses only about 250w. It has a stainless steel drum which should be long lasting too. It's not cheap, and is designed for bedsits and student accommodation, but suits us well. It's well designed, and clever. For example. it never jostles out of control while spinning, but seems to have a way of stabilising the load prior to spinning up to speed.

But given given the topic of this post, there is a but... A load in the old twin tub consisted of 15 minutes of wash cycle followed by 5 minutes of spinning.  The new machine works for 40 minutes, although it rinses twice and spins three times in that time too. So we end up using more power, but not so much that we begrudge it at all. The winter routine, unless gales are raging, may include running the generator while doing the washing, to ensure that the voltage does not get too low, but it's no bad thing and helps the longevity of the battery bank. That was true of the twin tub too.

When we see adverts on TV showing someone who wants to wear one particular shirt, and wastefully puts it in the washing machine along with expensively packaged detergent, we have it confirmed that the apparent restrictions in the way we live are, in truth, remarkably liberating.

Saturday, October 9 2021

Squeezing a Raspberry Pi service down a slow Internet link.

Our home Nextcloud installation works well, but when away from home, the heavily constrained bandwidth of abysmal rural broadband makes it close to unusable. Fortunately, there are ways of resolving the problem.

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Wednesday, May 26 2021

MONIToring network services

Simple small-scale service monitoring - Can Monit out-Nagios Nagios?

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Saturday, April 10 2021

Lighttpd and Nextcloud 21+

An irritating but apparently harmless notice when updating to Nextcloud 21 needs a slight change to the web server configuration under Lighttpd

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Monday, February 22 2021

OpenSUSE as a Raspberry Pi 4 Server

A work-in-progress series of notes on a migration to OpenSUSE as a server on a Raspberry Pi 4.  These notes are somewhat rambling, as they were written during the development process of the new server, but are left here, warts and all.


Migration project status: The project has been completed successfully. All services are now running under OpenSUSE as of 6th March 2021. I moaned and grumbled my way through this post, adding to it as issues arose or little triumphs were achieved. The reality is that what felt like little hacks, workarounds and customising I had to do, tiny things, really, were probably no more than were helping the stability of the previous system, but time and familiarity had made me forget that's how sysadmins make things work.
This has been an interesting exercise, and I plan to leave these notes here, both for my own reference and possibly as some might be useful to others.

One month later:  I remain pleased with the decision to migrate from Raspberry Pi OS to OpenSUSE for this server.  In fact, I wish I could easily migrate a hosted Raspberry Pi I have.  The most pressing issues I have faced were with regard to various weekly security and performance reports I have written over the years. I am still getting to grips with systemd's timers and logrotate, as some of the reports should run after the logs are rotated, but I am still not clear when these happen. One unexpected bonus is the degree to which btrfs compression works.  At the moment, there is a 25% space saving on the disk.  The next big test will be with the release of OpenSUSE 15.3. Previous experience on x86 suggests this update will be straight forward,  so I am expecting more of the solidity I am currently enjoying.

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Omeka under Lighttpd

Documented for those wanting to try this out

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Saturday, January 16 2021

Our own xmpp server, with all the trimmings

We can bypass all the data slurping and other issues, by running our own messaging service, including voice and video, and group chats.

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Tuesday, September 15 2020

The Cycles of History

We are living part of history. How we relate to that may be a key coping strategy in the years to come.

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