16 ms·

How much load can be served from 1m² of sunlight

186 points by forkfork 5y ago

ed25519FUUU 5y ago
> 12v to 240v inverter Can someone explain this part of his equation? What’s he doing with 240v? Or maybe he meant 24v for charging the laptop?
- ketralnis 5y ago
  He's in Australia which uses 240v mains power. He's using an inverter to connect his regular old laptop charger plug.
- philipkglass 5y ago
  He's using a household solar inverter designed to convert low voltage DC to AC at standard wall socket voltage. It's not the most efficient approach, as noted in other comments, but it's an easy approach since these inverters are common and a laptop's power supply is already set up to plug into a wall socket.
  - forkfork 5y ago
    Yep! Inefficient, but it is what I have, and there is no risk to frying my moderately expensive laptop which I hope to keep running for many years.
turtlebits 5y ago
The title is a bit misleading as it's specific to the OPs setup (which is quite inefficient). Would have liked to to see numbers of how much power is actually being output by the panel, and a shunt on the battery to see accurate consumption.
danuker 5y ago
Rather than inverting 12V DC to 240V AC and back, you could skip a step and use a laptop car charger, converting 12V DC straight to ~20V DC.
- tonymet 5y ago
  the efficiency savings with this approach will outweigh any other effort
  - WJW 5y ago
    I don't think that's true. There are plenty of low-power setups that consume less than 2 watts, for an instant gain of 6/7ths or 85%. DC-to-AC-to-DC conversion is less than ideal, but even at a low estimate of only 90% efficiency at each step, that'd still be only a 1.0-(0.9^3)= ~28% loss.
    - p1mrx 5y ago
      I don't think % efficiency tells the whole story, because those numbers are measured under load. A 12V->240V inverter probably burns a lot of power just sitting idle, so the efficiency curve starts at 0%. You really need to know (or measure) that curve's overall shape.
- na85 5y ago
  Don't DC-DC transformers use AC internally?
  - dreamcompiler 5y ago
    Yes but it's kHz-range PWM square-wave AC; there's no 60Hz sinewave involved. Converting to/from a 60Hz sinewave requires extra circuitry that decreases efficiency. And in this application a 60Hz AC sinewave serves no useful purpose.
  - jagger27 5y ago
    The point is to remove the laptop power brick. Let's say the laptop charger is 90% efficient, which is fairly typical. The post claims their 12VDC to 240VAC inverter is 92% efficient. A 12VDC to 20VDC voltage booster would only have to be >83% efficient to beat that setup.
    - 5y ago
PragmaticPulp 5y ago
Obviously there is infinite room for optimization of this problem, but this was a fun blog post. I’m interested to see where the author goes with the series.
- lmilcin 5y ago
  It is interesting concept for a blog post but ruined by very inefficient implementation. I would expect orders of magnitude more work done on ~20W. Also parsing a compressed 10MB JSON seems like an unusual request. It would maybe be more fun to put a Hello World or Pet Store and get some numbers that will be more relatable to a regular developer.
  - mhink 5y ago
    I mean, everyone's gotta start somewhere. I'll give the author props for coming up with an idea for an experiment, documenting it, and sharing their results. Not a whole lot of people do that out in the open, and it's great to see a bunch of responses with suggestions for further improvements. :)
  - f00zz 5y ago
    Years ago someone made a potato-powered web server. It was an 8-bit microcontroller with a custom TCP/IP stack, if I remember correctly.
  - dylan604 5y ago
    You must have a very low level of expectations of your fellow HN reader if you think that anything above a Hello World tutorial is relatable to a regular developer.
    - lmilcin 5y ago
      How frequently do you test a new web framework with "10MB compressed JSONs"? On the other hand you can find a lot of benchmarks that use basically Hello World just to test your request response or some rather small request/response sizes, because this is what most applications actually do. You can add a simple database query to it for more realistic load. So, yes, this is more relatable to me as a backend developer because I can compare results more easily.
sparsely 5y ago
Cool idea, the numbers in this blog post are very much a worst case scenario outside of running the entire process on 1080 GPU or something though
jakogut 5y ago
> With an idle load, this particular laptop draws 14W of power with the screen turned off. That's an extremely high idle power usage, I also have a laptop with a Ryzen 9 4900HS (the ROG Zephyrus G14, the only laptop with this chip, to my knowledge), and it idles around 9-11W with the screen on. Most of that is actually because of the RTX 2060 that's bundled with it, and won't turn off in Linux because Nvidia doesn't give a shit. I also suspect the author doesn't have a lot of power saving tunables enabled. By comparison, another laptop I have with a 4700U (also eight cores) and no discrete GPU idles at 2-3W. EDIT: If this author is reading this, this [0] is a good page to start from, along with powertop. I'd install and enable TLP, disable boost for efficiency, enable the tunables suggested by powertop, and maybe try nouveau for putting the GPU in the lowest power state. [0] https://wiki.archlinux.org/title/Power_management https://wiki.archlinux.org/title/Power_management
- walrus01 5y ago
  For computing efficiency comparison purposes a very old Thinkpad x40 laptop with a single core CPU, 1.5GB RAM and the screen off idles at about 12.5W, at a unix load of 0.02
- aero-glide2 5y ago
  You can use nvidia-prime to run on intel only right?
  - Ballas 5y ago
    > run on intel only How does that work on a Ryzen laptop?
    - fragmede 5y ago
      The English doesn't (quite work), but Intel here refers to the integrated, power-thrifty GPU, so could be more pedantically stated as "run on integrated graphics chip and turn off the Nvidia discrete GPU (and save power)" instead.
      - 5y ago
jacob019 5y ago
You won't get 200W from a 200W panel in direct sunlight, but it will still generate some watts at other times, so it should work out. "A 4.6b year old yellow dwarf as a light source" loved that
- plorg 5y ago
  In power systems there is a number called the capacity factor that is used to relate the average actual output to the nameplate capacity over whatever time interval. In this article the author note that they are expecting 600Wh in a day, or about an average of 3h at nameplate capacity. That works out to a capacity factor of about 0.13, which sounds about right for a solar installation that wasn't purpose built in an area of high insolation.
- dreamcompiler 5y ago
  Did you mean "except in direct sunlight"?
  - jacob019 5y ago
    The nominal rating is a peak rating, in my experience the sustained output will be somewhat less, even in direct sunlight.
    - lazide 5y ago
      Nod, unless you are in a place on the planet with perfect insolation (which would still only happen a few weeks of the year), it will nearly always will be below nameplate rating. The nameplate rating/testing if ever done, is done in a test bed with artificial light and perfect angle. Edit: I remember I did once get an above nameplate actual power output from a panel once - using MPPT, at high altitude, at the maximum insolation time for the year (mid-California in the mountains, right around the summer solstice). It only lasted for 20 minutes though.
- rexreed 5y ago
  I thought that was factored in when he talked about 3 full-hours of 200W across the full day? The day in Australia is certainly longer than 3 hours, so I figured that accounted for panel inefficiencies, indirect sunlight, and other such things. But could be wrong. Not sure how the 3 hours was calculated, but I am sure some solar calculators will take your location, average annual sunlight, efficiency and spit out an "effective daily solar hours" value that can be multiplied by the indicated solar panel wattage.
giantg2 5y ago
What about router/modem power draw? Needs to be some sort of connection to the internet to truly function as a website. (Not being connected would mean it's a wan site or intranet site)
- forkfork 5y ago
  Good point. There is: a HFC modem & 2x Google Wifi access points. Totals to about 15W of energy use - which only leaves enough energy budget for a Raspberry Pi.
amelius 5y ago
What if you ditch the OS and code the server on the bare metal?
- wizzwizz4 5y ago
  The OS is very rarely the bottleneck.
  - amelius 5y ago
    Until it becomes the bottleneck.
    - imoverclocked 5y ago
      This person is running node.js. I seriously doubt the OS is the bottleneck.
      - forkfork 5y ago
        The bottleneck is gunzipping & deserializing a huge JSON object using a very slow language (Node.js). This was attempting to simulate the type of load I see in the wild, rather than serving "Hello world" using C++.
alacritas0 5y ago
To see another attempt of serving a webpage off of solar power: take a look at https://solar.lowtechmagazine.com/about.html https://solar.lowtechmagazine.com/about.html -- it has techniques I find pretty unique for conserving power. All the images are rasterized in order to reduce page size among other things.
tantalor 5y ago
What is the bottleneck is this system?
- daneel_w 5y ago
  The detour of 12 volts -> mains voltage -> back to low voltage is a big one, for starters.
  - lazide 5y ago
    Also what most folks end up doing for convenience. It can be surprisingly inconvenient and expensive to source a power supply at 12v/24v/48v or whatever, and battery voltages are always nominal (think barely approximate), so you can’t get clean power regulated directly sufficient for running a computer. For instance, “12v” automotive voltages can vary from 8v to 15v during normal vehicle operation - like starting the vehicle, charging at full tilt on the highway, etc. a full battery can provide 13.7-14.8v depending on chemistry too.
- dotancohen 5y ago
  Theoretical: Amount of energy in sunlight. Practical: The creativity of the engineer building it.
karkisuni 5y ago
Adding the obligatory "what if M1" comment. Anandtech tested power draw of an M1 Mac Mini and found 4.2W at idle, 26.5W for the average multithreaded workload. 1/3rd idle power and the same power draw while running multithreaded benchmarks compared to the laptop serving a single client. Would be interesting to compare. https://www.anandtech.com/show/16252/mac-mini-apple-m1-tested https://www.anandtech.com/show/16252/mac-mini-apple-m1-teste...
- sfblah 5y ago
  For the load expected for pulling data from a simple redis cache, is an M1 actually the most efficient chip? Isn't the point of the M1 that it supports a bunch of complex workflows while remaining efficient? Aren't there even more power efficient chips out there that focus exclusively on simple integer operations, etc.?
  - judge2020 5y ago
    Sure. "STM32L1 MCUs also feature the industry's lowest power consumption of 170 nA in low-power mode with SRAM retention. ". But I think we're looking for the 'most efficient' general purpose computer. https://www.st.com/en/microcontrollers-microprocessors/stm32-ultra-low-power-mcus.html#:~:text=power%20consumption%20of-,170%20nA,-in%20low-power https://www.st.com/en/microcontrollers-microprocessors/stm32...
    - genewitch 5y ago
      Intel also made the quark which is a 486 that runs on a button cell battery, the same type that we'd call a cmos battery.
  - masklinn 5y ago
    > For the load expected for pulling data from a simple redis cache, is an M1 actually the most efficient chip? I think that's a good question with no trivial answer, there are certainly boards which consume significantly less energy than that and can serve traffic (using nginx and static content you can serve quite a lot on a watt or two, per https://solar.lowtechmagazine.com/2020/01/how-sustainable-is-a-solar-powered-website.html https://solar.lowtechmagazine.com/2020/01/how-sustainable-is...), however if you factor in the need for actual CPU...
Amorymeltzer 5y ago
The point of the piece is at the bottom: >By increasing our utilization rate, we have increased power efficiency by a factor of 6. >Economies of scale are more important than intuition would suggest for efficiently serving requests
ananonymoususer 5y ago
I did this 20 years ago and ran the server for about 10 years. I down-scaled the server hardware when I transitioned to solar, but soon discovered that the low-power server just could not keep up with the demand. I upgraded to something in the middle that could handle a decent number of web users while still not using all the solar. I had 1280W of panels (16x80), a 1500W inverter, and three deep-cycle 12V 50AH batteries. The remnants of the system can still be seen here: http://jsl.com/solar http://jsl.com/solar
- the-dude 5y ago
  Link is dead. So how much did the upgraded server draw?
  - ananonymoususer 5y ago
    See above.
- louwrentius 5y ago
  Site seems down? https://web.archive.org/web/20160401215358/http://www.jsl.com/solar/ https://web.archive.org/web/20160401215358/http://www.jsl.co...
  - junon 5y ago
    Probably hugged a bit, it works for me.
- masklinn 5y ago
  What was the demand? 1200W seems like a lot, https://solar.lowtechmagazine.com https://solar.lowtechmagazine.com runs on a 50W solar panel with a 168W lead-acid battery (non-deep-cycle so effectively 84Wh). However it gets to have fully static content, and benefits from relatively modern hardware: for under 2W it runs on a dual-core 1GHz ARM with 1GB RAM (and a 16GB SD card but it doesn't use anywhere near 16GB).
  - 5y ago
rzimmerman 5y ago
It would be interesting to set up a server/PC that throttled The CPUs/GPUs by power use rather than thermal readings. It’s analogous to the burst credit system used on some EC2 instances, but it would be a cool kernel or hardware feature for devices that are completely solar powered.
louwrentius 5y ago
I run my static blog on a Raspberry Pi3B+ Powered by solar [0] and it doesn’t even flinch when it is hit by hacker news. It idles at around 3.1 watts and that power usage includes a step down converter from 12 volt to 5 volt. A bunch of lead acid batteries of various capacities provide backup. Lead acid is a terrible choice because charge times are long, but it is sufficient for now. Just see it as performance art. [0]: https://louwrentius.com/this-blog-is-now-running-on-solar-power.html https://louwrentius.com/this-blog-is-now-running-on-solar-po...
seanwilson 5y ago
Are smartphones a good option here in terms of energy use?
mywittyname 5y ago
Is there a name for this effect in an abstract sense? I see it pop up a lot where the gains from scaling are super-linear to the scale itself. Or is it just called "economies of scale".
- gberger 5y ago
  Marginal cost of production? If we take "energy consumption" to mean "cost", and "serving web requests" to mean "production", then your fixed cost is the idle energy load, and the marginal cost is how much more energy you would need to serve an additional request.
- seoulmetro 5y ago
  This has very little to do with scale. He didn't really scale up to get from 1 RPS to 12 RPS. It's just that he was already invested in a scale (full PC build drawing heaps of idle power) that didn't match his requirements. i.e. it's faster for a Tesla to go 5km than a plane when both are from rest. That doesn't mean that you've scaled up by using a Tesla to get there faster. You aren't going 12x faster by choosing the Tesla. You're just not going 12x slower. It's hard to write into words, but it's a dumb thing to say.
jeffbee 5y ago
This is an aburdly bad result, mostly caused by the questionable 14W base power draw, but also due to the questionable choice of gzip compression, which is not exactly on the frontier of compression technology. Even zlib-deflate would decompress twice as fast at the same size ratios, but something like lz4 or snappy would be an order of magnitude less CPU time cost for similar compressed size. The real way to have an energy-efficient service is to amortize away your idle usage and all of these inefficient conversion steps by just hosting your junk on App Engine.
- forkfork 5y ago
  I’ll iterate towards a good solution. This was a somewhat realistic but naive solution (I have customers doing largely what I’ve described in the article). If I could find a way to encourage people to run their work in a power efficient way using economies of scale from this series, I would be terribly happy. Interestingly I suspect public-cloud FaaS solutions (e.g. AWS Lambda) will achieve highest utilisation rates due to high rate of CPU sharing - but I’m a long way off from showing that with data.
lxe 5y ago
Technically, it should be "200 watts". The losses happen due to all the inversion and conversion (I think... right?)
- marcosdumay 5y ago
  TLDR (although it's quite short), he got 21W. The largest factor is the day-cycle. He gets 3 hours equivalent of Sun light a day. I really expected Australia to be more sunny than that.
  - hinkley 5y ago
    Planting trees around your house creates a lot of passive cooling, which can save you a lot of power on making the interior comfortable. It also makes roof top solar a bit of a joke.
  - forkfork 5y ago
    Mostly clouds and rain bring this down to 600Wh/day. Washed the bird poo off the panel to get an extra 2 watts.
londons_explore 5y ago
The authors "92%" efficiency calculations will be with the inverter and power supply at high load. When drawing only 20 watts, I expect you'll see more like 80% efficiency, and maybe as low as 50%.
- forkfork 5y ago
  I’ll try to measure this. I guess I need to purchase a shunt.
  - londons_explore 5y ago
    If you have a regular $3 multimeter, it should be able to measure current and voltage between the battery and inverter. Then just multiply. double check you're on the right mode and using the right socket on the meter before connecting, or you'll get a big bang!. For the AC side, it's much harder to measure - typical inverters have rather imperfect AC outputs, and unless you have a rather expensive multimeter you won't get an accurate power measurement. A kill-o-watt will probably be okay for a rough measurement, but there might well be a +- 20% error...
evancoop 5y ago
One question of great relevance is the change in the statistic implied by the article's title over the past couple decades, and the projected change in the decades to come. Is this Moore's-law-esque? If so, eventually, these concerns will be trivial. Is an asymptote approaching? If so, this metric becomes increasing relevant and crucial.
ketralnis 5y ago
The armchairs here are all great. If they used a raspberry pi and rewrote their javascript in ARM assembly and reinvented a more power-efficient compression algorithm and solved your favourite problem of serving static pages instead of the problem they actually want to solve, they could maybe get more instructions per watt. But really, I'm glad that they're actually doing it instead of talking about doing it and spending all of their time musing about _what if_ they did this other thing instead. This looks great.
- bo1024 5y ago
  I was confused about the "doing it" part. I see that they have all the materials and got some numbers like average power consumption, but they didn't seem to actually set it up and see how it worked?
  - forkfork 5y ago
    Author here - I’m learning as I go. I thought of talking a out the actual sunlight starting at closer to 1300W and losing efficiency at each step, but I don’t get have the right tools to do that properly. I’d def love to hear your suggestions though as I continue to iterate this one.
    - bo1024 5y ago
      I don't have experience but wishing you best of luck!
ctdonath 5y ago
I regularly work outside during summer, powering a MacBook Pro exclusively by sunlight (panel about 1m^2). For a few hours I can get a good 50+ watts, buffering thru a 100Wh battery. Keeping the load typically around 10-15 watts isn't hard, so long as paying attention. Of note, I persuaded Atlassian to remove the (rather nice) animated clouds from their "you have been logged out" web page because it pulled 30 watts (even when web page was hidden). Running on solar/battery exclusively, that was a problem; kudos to them for acting on it.
- turtlebits 5y ago
  50W seems rather low for a a 1m^2 panel. I have some older 250W panels (1.6m^2) and get around 220W in the summer. Also, how are you measuring a 10-15W load? When plugged in, the charger is going to pull it's rated load from your battery bank (I'm seeing ~84W including inverter losses).
  - ctdonath 5y ago
    System peaks around 57W, with battery charge rate limits and frequent environmental disruptions (clouds, angles, etc). Battery (Goal Zero Sherpa 100AC) shows output load. Lowest draw on MacBook Pro 15" is 7W, usually idling 10-15W, pulls about 50W when charging.
Robotbeat 5y ago
Of course, you can juice this a bit by doing two things: 1) using concentrating photovoltaics with multifunction solar cells to achieve ~30-40% efficiency. (This requires active cooling.) 2) use 2 axis tracking. 3) solar cells on the back of your array. (Bifacial solar arrays do this in an integrated manner but aren’t concentrating.) These three together give you on the order of a factor of 3 greater total energy. (Note: concentrating buys you about 20% greater raw efficiency BUT means capturing diffuse light basically doesn’t happen. Might be better off with a non-concentrating bifacial multijunction panel that is still two axis tracked. Concentrators can still help financially because multijunction solar panels are EXPENSIVE.) Also, if your laptop already has a beefy battery, you don’t need a separate battery. You’ll need a custom MPPT with the right output voltage, but you could hook it straight into your laptop. That saves money (potentially) and a lot of inefficiency.
rdevsrex 5y ago
I think the title is misleading because the load depends on, well, the workload. But it’s a thought provoking idea.
zbrozek 5y ago
I look forward to your next posts in the series! I'd start by skipping the inverter and using a car USB-C charger instead, then fussing with power settings to drive down the quiescent power of the laptop. Everything after that starts to feel like actual work, like changing the serving software or actively aiming the solar panel. You might be able to find some single board computer with a modern CPU and no graphics silicon whatsoever.
walrus01 5y ago
I would encourage anyone interested in this to go plug example size of small pv systems into this calculator for your location: https://pvwatts.nrel.gov/ https://pvwatts.nrel.gov/ You can use a round number like 1000W, which would be the same as four fairly cheap 250W 60 cell polycrystalline cell pv panels. You will get the cumulative kWh production expected per month.
desktopninja 5y ago
The curious brain cell in me would like to know if wget||curl + xargs -P $(nproc) + awk would produce more "efficient" results?

186 points by forkfork 5y ago

> 12v to 240v inverter Can someone explain this part of his equation? What’s he doing with 240v? Or maybe he meant 24v for charging the laptop?

ketralnis 5y ago
He's in Australia which uses 240v mains power. He's using an inverter to connect his regular old laptop charger plug.
philipkglass 5y ago
He's using a household solar inverter designed to convert low voltage DC to AC at standard wall socket voltage. It's not the most efficient approach, as noted in other comments, but it's an easy approach since these inverters are common and a laptop's power supply is already set up to plug into a wall socket.
- forkfork 5y ago
  Yep! Inefficient, but it is what I have, and there is no risk to frying my moderately expensive laptop which I hope to keep running for many years.

turtlebits 5y ago

The title is a bit misleading as it's specific to the OPs setup (which is quite inefficient). Would have liked to to see numbers of how much power is actually being output by the panel, and a shunt on the battery to see accurate consumption.

danuker 5y ago

Rather than inverting 12V DC to 240V AC and back, you could skip a step and use a laptop car charger, converting 12V DC straight to ~20V DC.

tonymet 5y ago
the efficiency savings with this approach will outweigh any other effort
- WJW 5y ago
  I don't think that's true. There are plenty of low-power setups that consume less than 2 watts, for an instant gain of 6/7ths or 85%. DC-to-AC-to-DC conversion is less than ideal, but even at a low estimate of only 90% efficiency at each step, that'd still be only a 1.0-(0.9^3)= ~28% loss.
  - p1mrx 5y ago
    I don't think % efficiency tells the whole story, because those numbers are measured under load. A 12V->240V inverter probably burns a lot of power just sitting idle, so the efficiency curve starts at 0%. You really need to know (or measure) that curve's overall shape.
na85 5y ago
Don't DC-DC transformers use AC internally?
- dreamcompiler 5y ago
  Yes but it's kHz-range PWM square-wave AC; there's no 60Hz sinewave involved. Converting to/from a 60Hz sinewave requires extra circuitry that decreases efficiency. And in this application a 60Hz AC sinewave serves no useful purpose.
- jagger27 5y ago
  The point is to remove the laptop power brick. Let's say the laptop charger is 90% efficient, which is fairly typical. The post claims their 12VDC to 240VAC inverter is 92% efficient. A 12VDC to 20VDC voltage booster would only have to be >83% efficient to beat that setup.
  - 5y ago

PragmaticPulp 5y ago

Obviously there is infinite room for optimization of this problem, but this was a fun blog post. I’m interested to see where the author goes with the series.

lmilcin 5y ago
It is interesting concept for a blog post but ruined by very inefficient implementation. I would expect orders of magnitude more work done on ~20W. Also parsing a compressed 10MB JSON seems like an unusual request. It would maybe be more fun to put a Hello World or Pet Store and get some numbers that will be more relatable to a regular developer.
- mhink 5y ago
  I mean, everyone's gotta start somewhere. I'll give the author props for coming up with an idea for an experiment, documenting it, and sharing their results. Not a whole lot of people do that out in the open, and it's great to see a bunch of responses with suggestions for further improvements. :)
- f00zz 5y ago
  Years ago someone made a potato-powered web server. It was an 8-bit microcontroller with a custom TCP/IP stack, if I remember correctly.
- dylan604 5y ago
  You must have a very low level of expectations of your fellow HN reader if you think that anything above a Hello World tutorial is relatable to a regular developer.
  - lmilcin 5y ago
    How frequently do you test a new web framework with "10MB compressed JSONs"? On the other hand you can find a lot of benchmarks that use basically Hello World just to test your request response or some rather small request/response sizes, because this is what most applications actually do. You can add a simple database query to it for more realistic load. So, yes, this is more relatable to me as a backend developer because I can compare results more easily.

sparsely 5y ago

Cool idea, the numbers in this blog post are very much a worst case scenario outside of running the entire process on 1080 GPU or something though

jakogut 5y ago

> With an idle load, this particular laptop draws 14W of power with the screen turned off. That's an extremely high idle power usage, I also have a laptop with a Ryzen 9 4900HS (the ROG Zephyrus G14, the only laptop with this chip, to my knowledge), and it idles around 9-11W with the screen on. Most of that is actually because of the RTX 2060 that's bundled with it, and won't turn off in Linux because Nvidia doesn't give a shit. I also suspect the author doesn't have a lot of power saving tunables enabled. By comparison, another laptop I have with a 4700U (also eight cores) and no discrete GPU idles at 2-3W. EDIT: If this author is reading this, this [0] is a good page to start from, along with powertop. I'd install and enable TLP, disable boost for efficiency, enable the tunables suggested by powertop, and maybe try nouveau for putting the GPU in the lowest power state. [0] https://wiki.archlinux.org/title/Power_management https://wiki.archlinux.org/title/Power_management

walrus01 5y ago
For computing efficiency comparison purposes a very old Thinkpad x40 laptop with a single core CPU, 1.5GB RAM and the screen off idles at about 12.5W, at a unix load of 0.02
aero-glide2 5y ago
You can use nvidia-prime to run on intel only right?
- Ballas 5y ago
  > run on intel only How does that work on a Ryzen laptop?
  - fragmede 5y ago
    The English doesn't (quite work), but Intel here refers to the integrated, power-thrifty GPU, so could be more pedantically stated as "run on integrated graphics chip and turn off the Nvidia discrete GPU (and save power)" instead.
    - 5y ago

jacob019 5y ago

You won't get 200W from a 200W panel in direct sunlight, but it will still generate some watts at other times, so it should work out. "A 4.6b year old yellow dwarf as a light source" loved that

plorg 5y ago
In power systems there is a number called the capacity factor that is used to relate the average actual output to the nameplate capacity over whatever time interval. In this article the author note that they are expecting 600Wh in a day, or about an average of 3h at nameplate capacity. That works out to a capacity factor of about 0.13, which sounds about right for a solar installation that wasn't purpose built in an area of high insolation.
dreamcompiler 5y ago
Did you mean "except in direct sunlight"?
- jacob019 5y ago
  The nominal rating is a peak rating, in my experience the sustained output will be somewhat less, even in direct sunlight.
  - lazide 5y ago
    Nod, unless you are in a place on the planet with perfect insolation (which would still only happen a few weeks of the year), it will nearly always will be below nameplate rating. The nameplate rating/testing if ever done, is done in a test bed with artificial light and perfect angle. Edit: I remember I did once get an above nameplate actual power output from a panel once - using MPPT, at high altitude, at the maximum insolation time for the year (mid-California in the mountains, right around the summer solstice). It only lasted for 20 minutes though.
rexreed 5y ago
I thought that was factored in when he talked about 3 full-hours of 200W across the full day? The day in Australia is certainly longer than 3 hours, so I figured that accounted for panel inefficiencies, indirect sunlight, and other such things. But could be wrong. Not sure how the 3 hours was calculated, but I am sure some solar calculators will take your location, average annual sunlight, efficiency and spit out an "effective daily solar hours" value that can be multiplied by the indicated solar panel wattage.

giantg2 5y ago

What about router/modem power draw? Needs to be some sort of connection to the internet to truly function as a website. (Not being connected would mean it's a wan site or intranet site)

forkfork 5y ago
Good point. There is: a HFC modem & 2x Google Wifi access points. Totals to about 15W of energy use - which only leaves enough energy budget for a Raspberry Pi.

amelius 5y ago

What if you ditch the OS and code the server on the bare metal?

wizzwizz4 5y ago
The OS is very rarely the bottleneck.
- amelius 5y ago
  Until it becomes the bottleneck.
  - imoverclocked 5y ago
    This person is running node.js. I seriously doubt the OS is the bottleneck.
    - forkfork 5y ago
      The bottleneck is gunzipping & deserializing a huge JSON object using a very slow language (Node.js). This was attempting to simulate the type of load I see in the wild, rather than serving "Hello world" using C++.

alacritas0 5y ago

To see another attempt of serving a webpage off of solar power: take a look at https://solar.lowtechmagazine.com/about.html https://solar.lowtechmagazine.com/about.html -- it has techniques I find pretty unique for conserving power. All the images are rasterized in order to reduce page size among other things.

tantalor 5y ago

What is the bottleneck is this system?

daneel_w 5y ago
The detour of 12 volts -> mains voltage -> back to low voltage is a big one, for starters.
- lazide 5y ago
  Also what most folks end up doing for convenience. It can be surprisingly inconvenient and expensive to source a power supply at 12v/24v/48v or whatever, and battery voltages are always nominal (think barely approximate), so you can’t get clean power regulated directly sufficient for running a computer. For instance, “12v” automotive voltages can vary from 8v to 15v during normal vehicle operation - like starting the vehicle, charging at full tilt on the highway, etc. a full battery can provide 13.7-14.8v depending on chemistry too.
dotancohen 5y ago
Theoretical: Amount of energy in sunlight. Practical: The creativity of the engineer building it.

karkisuni 5y ago

Adding the obligatory "what if M1" comment. Anandtech tested power draw of an M1 Mac Mini and found 4.2W at idle, 26.5W for the average multithreaded workload. 1/3rd idle power and the same power draw while running multithreaded benchmarks compared to the laptop serving a single client. Would be interesting to compare. https://www.anandtech.com/show/16252/mac-mini-apple-m1-tested https://www.anandtech.com/show/16252/mac-mini-apple-m1-teste...

sfblah 5y ago
For the load expected for pulling data from a simple redis cache, is an M1 actually the most efficient chip? Isn't the point of the M1 that it supports a bunch of complex workflows while remaining efficient? Aren't there even more power efficient chips out there that focus exclusively on simple integer operations, etc.?
- judge2020 5y ago
  Sure. "STM32L1 MCUs also feature the industry's lowest power consumption of 170 nA in low-power mode with SRAM retention. ". But I think we're looking for the 'most efficient' general purpose computer. https://www.st.com/en/microcontrollers-microprocessors/stm32-ultra-low-power-mcus.html#:~:text=power%20consumption%20of-,170%20nA,-in%20low-power https://www.st.com/en/microcontrollers-microprocessors/stm32...
  - genewitch 5y ago
    Intel also made the quark which is a 486 that runs on a button cell battery, the same type that we'd call a cmos battery.
- masklinn 5y ago
  > For the load expected for pulling data from a simple redis cache, is an M1 actually the most efficient chip? I think that's a good question with no trivial answer, there are certainly boards which consume significantly less energy than that and can serve traffic (using nginx and static content you can serve quite a lot on a watt or two, per https://solar.lowtechmagazine.com/2020/01/how-sustainable-is-a-solar-powered-website.html https://solar.lowtechmagazine.com/2020/01/how-sustainable-is...), however if you factor in the need for actual CPU...

Amorymeltzer 5y ago

The point of the piece is at the bottom: >By increasing our utilization rate, we have increased power efficiency by a factor of 6. >Economies of scale are more important than intuition would suggest for efficiently serving requests

ananonymoususer 5y ago

I did this 20 years ago and ran the server for about 10 years. I down-scaled the server hardware when I transitioned to solar, but soon discovered that the low-power server just could not keep up with the demand. I upgraded to something in the middle that could handle a decent number of web users while still not using all the solar. I had 1280W of panels (16x80), a 1500W inverter, and three deep-cycle 12V 50AH batteries. The remnants of the system can still be seen here: http://jsl.com/solar http://jsl.com/solar

the-dude 5y ago
Link is dead. So how much did the upgraded server draw?
- ananonymoususer 5y ago
  See above.
louwrentius 5y ago
Site seems down? https://web.archive.org/web/20160401215358/http://www.jsl.com/solar/ https://web.archive.org/web/20160401215358/http://www.jsl.co...
- junon 5y ago
  Probably hugged a bit, it works for me.
masklinn 5y ago
What was the demand? 1200W seems like a lot, https://solar.lowtechmagazine.com https://solar.lowtechmagazine.com runs on a 50W solar panel with a 168W lead-acid battery (non-deep-cycle so effectively 84Wh). However it gets to have fully static content, and benefits from relatively modern hardware: for under 2W it runs on a dual-core 1GHz ARM with 1GB RAM (and a 16GB SD card but it doesn't use anywhere near 16GB).
- 5y ago

rzimmerman 5y ago

It would be interesting to set up a server/PC that throttled The CPUs/GPUs by power use rather than thermal readings. It’s analogous to the burst credit system used on some EC2 instances, but it would be a cool kernel or hardware feature for devices that are completely solar powered.

louwrentius 5y ago

I run my static blog on a Raspberry Pi3B+ Powered by solar [0] and it doesn’t even flinch when it is hit by hacker news. It idles at around 3.1 watts and that power usage includes a step down converter from 12 volt to 5 volt. A bunch of lead acid batteries of various capacities provide backup. Lead acid is a terrible choice because charge times are long, but it is sufficient for now. Just see it as performance art. [0]: https://louwrentius.com/this-blog-is-now-running-on-solar-power.html https://louwrentius.com/this-blog-is-now-running-on-solar-po...

seanwilson 5y ago

Are smartphones a good option here in terms of energy use?

mywittyname 5y ago

Is there a name for this effect in an abstract sense? I see it pop up a lot where the gains from scaling are super-linear to the scale itself. Or is it just called "economies of scale".

gberger 5y ago
Marginal cost of production? If we take "energy consumption" to mean "cost", and "serving web requests" to mean "production", then your fixed cost is the idle energy load, and the marginal cost is how much more energy you would need to serve an additional request.
seoulmetro 5y ago
This has very little to do with scale. He didn't really scale up to get from 1 RPS to 12 RPS. It's just that he was already invested in a scale (full PC build drawing heaps of idle power) that didn't match his requirements. i.e. it's faster for a Tesla to go 5km than a plane when both are from rest. That doesn't mean that you've scaled up by using a Tesla to get there faster. You aren't going 12x faster by choosing the Tesla. You're just not going 12x slower. It's hard to write into words, but it's a dumb thing to say.

jeffbee 5y ago

This is an aburdly bad result, mostly caused by the questionable 14W base power draw, but also due to the questionable choice of gzip compression, which is not exactly on the frontier of compression technology. Even zlib-deflate would decompress twice as fast at the same size ratios, but something like lz4 or snappy would be an order of magnitude less CPU time cost for similar compressed size. The real way to have an energy-efficient service is to amortize away your idle usage and all of these inefficient conversion steps by just hosting your junk on App Engine.

forkfork 5y ago
I’ll iterate towards a good solution. This was a somewhat realistic but naive solution (I have customers doing largely what I’ve described in the article). If I could find a way to encourage people to run their work in a power efficient way using economies of scale from this series, I would be terribly happy. Interestingly I suspect public-cloud FaaS solutions (e.g. AWS Lambda) will achieve highest utilisation rates due to high rate of CPU sharing - but I’m a long way off from showing that with data.

lxe 5y ago

Technically, it should be "200 watts". The losses happen due to all the inversion and conversion (I think... right?)

marcosdumay 5y ago
TLDR (although it's quite short), he got 21W. The largest factor is the day-cycle. He gets 3 hours equivalent of Sun light a day. I really expected Australia to be more sunny than that.
- hinkley 5y ago
  Planting trees around your house creates a lot of passive cooling, which can save you a lot of power on making the interior comfortable. It also makes roof top solar a bit of a joke.
- forkfork 5y ago
  Mostly clouds and rain bring this down to 600Wh/day. Washed the bird poo off the panel to get an extra 2 watts.

londons_explore 5y ago

The authors "92%" efficiency calculations will be with the inverter and power supply at high load. When drawing only 20 watts, I expect you'll see more like 80% efficiency, and maybe as low as 50%.

forkfork 5y ago
I’ll try to measure this. I guess I need to purchase a shunt.
- londons_explore 5y ago
  If you have a regular $3 multimeter, it should be able to measure current and voltage between the battery and inverter. Then just multiply. double check you're on the right mode and using the right socket on the meter before connecting, or you'll get a big bang!. For the AC side, it's much harder to measure - typical inverters have rather imperfect AC outputs, and unless you have a rather expensive multimeter you won't get an accurate power measurement. A kill-o-watt will probably be okay for a rough measurement, but there might well be a +- 20% error...

evancoop 5y ago

One question of great relevance is the change in the statistic implied by the article's title over the past couple decades, and the projected change in the decades to come. Is this Moore's-law-esque? If so, eventually, these concerns will be trivial. Is an asymptote approaching? If so, this metric becomes increasing relevant and crucial.

ketralnis 5y ago

The armchairs here are all great. If they used a raspberry pi and rewrote their javascript in ARM assembly and reinvented a more power-efficient compression algorithm and solved your favourite problem of serving static pages instead of the problem they actually want to solve, they could maybe get more instructions per watt. But really, I'm glad that they're actually doing it instead of talking about doing it and spending all of their time musing about _what if_ they did this other thing instead. This looks great.

bo1024 5y ago
I was confused about the "doing it" part. I see that they have all the materials and got some numbers like average power consumption, but they didn't seem to actually set it up and see how it worked?
- forkfork 5y ago
  Author here - I’m learning as I go. I thought of talking a out the actual sunlight starting at closer to 1300W and losing efficiency at each step, but I don’t get have the right tools to do that properly. I’d def love to hear your suggestions though as I continue to iterate this one.
  - bo1024 5y ago
    I don't have experience but wishing you best of luck!

ctdonath 5y ago

I regularly work outside during summer, powering a MacBook Pro exclusively by sunlight (panel about 1m^2). For a few hours I can get a good 50+ watts, buffering thru a 100Wh battery. Keeping the load typically around 10-15 watts isn't hard, so long as paying attention. Of note, I persuaded Atlassian to remove the (rather nice) animated clouds from their "you have been logged out" web page because it pulled 30 watts (even when web page was hidden). Running on solar/battery exclusively, that was a problem; kudos to them for acting on it.

turtlebits 5y ago
50W seems rather low for a a 1m^2 panel. I have some older 250W panels (1.6m^2) and get around 220W in the summer. Also, how are you measuring a 10-15W load? When plugged in, the charger is going to pull it's rated load from your battery bank (I'm seeing ~84W including inverter losses).
- ctdonath 5y ago
  System peaks around 57W, with battery charge rate limits and frequent environmental disruptions (clouds, angles, etc). Battery (Goal Zero Sherpa 100AC) shows output load. Lowest draw on MacBook Pro 15" is 7W, usually idling 10-15W, pulls about 50W when charging.

Robotbeat 5y ago

Of course, you can juice this a bit by doing two things: 1) using concentrating photovoltaics with multifunction solar cells to achieve ~30-40% efficiency. (This requires active cooling.) 2) use 2 axis tracking. 3) solar cells on the back of your array. (Bifacial solar arrays do this in an integrated manner but aren’t concentrating.) These three together give you on the order of a factor of 3 greater total energy. (Note: concentrating buys you about 20% greater raw efficiency BUT means capturing diffuse light basically doesn’t happen. Might be better off with a non-concentrating bifacial multijunction panel that is still two axis tracked. Concentrators can still help financially because multijunction solar panels are EXPENSIVE.) Also, if your laptop already has a beefy battery, you don’t need a separate battery. You’ll need a custom MPPT with the right output voltage, but you could hook it straight into your laptop. That saves money (potentially) and a lot of inefficiency.

rdevsrex 5y ago

I think the title is misleading because the load depends on, well, the workload. But it’s a thought provoking idea.

zbrozek 5y ago

I look forward to your next posts in the series! I'd start by skipping the inverter and using a car USB-C charger instead, then fussing with power settings to drive down the quiescent power of the laptop. Everything after that starts to feel like actual work, like changing the serving software or actively aiming the solar panel. You might be able to find some single board computer with a modern CPU and no graphics silicon whatsoever.

walrus01 5y ago

I would encourage anyone interested in this to go plug example size of small pv systems into this calculator for your location: https://pvwatts.nrel.gov/ https://pvwatts.nrel.gov/ You can use a round number like 1000W, which would be the same as four fairly cheap 250W 60 cell polycrystalline cell pv panels. You will get the cumulative kWh production expected per month.

desktopninja 5y ago

The curious brain cell in me would like to know if wget||curl + xargs -P $(nproc) + awk would produce more "efficient" results?