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How Sustainable Is a Solar Powered Website?

lowtechmagazine.com

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Re: How Sustainable Is a Solar Powered Website?

#51

Post by maelito »

> However, we’re comparing apples to oranges. We have calculated our emissions based on the embodied energy of our installation. When the carbon intensity of the Spanish power grid is measured, the embodied energy of the renewable power infrastructure is taken to be zero. If we calculated our carbon intensity in the same way, of course it would be zero, too.

I don't get it. The carbon intensity of the national grid should result from a life-cycle analysis, so all emissions should be included in the figure. As far as I know, apples and apples are compared, and the home-made version is worse.

Re: How Sustainable Is a Solar Powered Website?

#52

Post by tr352 »

dragontamer wrote: post #37
jedberg wrote: post #13

I feel like they could get almost 100% uptime with a lot less effort if they just put a second server on the other side of the world. The antipode of Barcelona (where this is based) is pretty close to New Zealand. If they put a second server there and then used a anycast IP, chances are one of the servers would be up at all times with no battery at all. Edit: Changed multicast to anycast because for some reason my co…

For more local purposes, solar + wind is a nice complement. Wind is strongest at night, while solar is best in the day. Nuclear usually needs to keep running, and fewer people use electricity at night (unless you live in Philippines where it is common to only run AC at night to save on electricity).

> Wind is strongest at night

This depends on where you are. In many places wind is actually strongest during daytime.

Re: How Sustainable Is a Solar Powered Website?

#54

Post by rebuilder »

hannob wrote: post #26

This may sound snarky, but... I really wonder how helpful such projects are. Making the Internet greener is undoubtedly an important goal, but I feel this is perpetuating a myth that we're gonna fix the climate crisis with small-scale projects from below. Practically this is doing nothing to provide any relevant fix for the problem. What we should be doing is thinking about how we can fix the problem at scale, e.g. p…

I think it's a good way of finding and demonstrating the real-life gotchas of sustainable energy. For example, I don't think most people have a good understanding of the cost-benefit calculations that go into how much renewable energy production capacity we can build while keeping to co2 emission targets, given that new capacity needs to be built with the current energy setup. The "embodied energy" aspect of this article illustrates that.

Re: How Sustainable Is a Solar Powered Website?

#55

Post by lightedman »

kragen wrote: post #50
driverdan wrote: post #45

Earlier quoted context omitted.

You wouldn't want to power directly from the panels without a battery. It would cause high instability on cloudy days, possibly leading to file system corruption.

The panel voltage is pretty stable until the illuminance gets really low (unless you're drawing a lot of current). Diodes such as solar cells are roughly constant-voltage devices. You can get a pretty long way avoiding filesystem corruption by mounting things read-only, but (I've heard) some SSDs aren't really read-only even when they're read-only, because of read disturb and the attempt to compensate for it in the F…

"The panel voltage is pretty stable until the illuminance gets really low"

I'd like to see what panels those are, because the ones I've built while working as a PV manufacturing tech, both mono and poly (roughly 21% efficiency,) will have greatly varying voltages with even the tiniest hint of cloud cover over one cell, even with the junction box working to help separate out sections of the panel to maintain better voltages. Typical 60 cell 30-32V panel will drop to ~18-20 with just two cells on one 20-cell section of the panel covered. Sure this is still enough for the paltry voltage this specific server needs, but if they used smaller and more affordable panels like those used for cell phone chargers or similar size (within about 18"x18" form factor,) I can guarantee you those do not take to shading or even bad orientation well at all. 45 degrees off direct-exposure and you could be looking at that smaller panel producing a mere 2V or less.

Re: How Sustainable Is a Solar Powered Website?

#56

Post by philipkglass »

The author is drastically overestimating the lifecycle emissions and embodied energy of modern solar photovoltaic modules.

The article claims that it takes "3,514 MJ of energy to produce one m2 of solar panel."

The source for that assertion is this article from 2017:

"Energy Payback Time of a Solar Photovoltaic PoweredWaste Plastic Recyclebot System"

https://www.e-helvetica.nb.admin.ch/api/download/urn%3Anbn%3...

That article cites this article from 2006 as its source for energy intensity of solar manufacturing:

"Embodied energy analysis of photovoltaic (PV) system based on macro- and micro-level"

https://sci-hub.tw/10.1016/j.enpol.2005.06.018

That publication finds that silicon purification and processing accounts for the lion's share of embodied energy in solar PV.

But if you read section 6 of the paper, "Embodied energy of silicon purification and processing", you see that those authors are using material production energy intensity numbers from 2004 and 1998. They are also assuming the use of electronic grade silicon for solar manufacturing, and a silicon requirement of 12 grams per watt-peak of solar module. Cheaper and less energy intensive solar grade silicon has entirely replaced electronic grade silicon in PV since the early 2000s. Modern solar module silicon use is about 3 grams per watt-peak, not 12; see Table 1 in https://pubs.rsc.org/en/content/articlehtml/2020/ee/c9ee0245....

What first appears to be a reasonably recent citation for PV embodied energy is actually a chain of painfully outdated assumptions going all the way back to the 1990s.

Re: How Sustainable Is a Solar Powered Website?

#57

Post by falcolas »

About $100 in gear ($30 144wh battery, $20 controller, $50 50w solar panel) to offset around $2 worth of electricity (9.53kwh * 0.17 euro/kwh) per year.

The battery should be replaced about every 5 years, the solar panels 25 years, the controller every 10 years.

Re: How Sustainable Is a Solar Powered Website?

#58

Post by falcolas »

EGreg wrote: post #46
dragontamer wrote: post #37

Earlier quoted context omitted.

For more local purposes, solar + wind is a nice complement. Wind is strongest at night, while solar is best in the day. Nuclear usually needs to keep running, and fewer people use electricity at night (unless you live in Philippines where it is common to only run AC at night to save on electricity).

Also, you can use a refrigerator at night... the cold IS the battery.

That makes me wonder the viability of using a peltier as the pump/sink for a temperature differential battery.

Re: How Sustainable Is a Solar Powered Website?

#59

Post by kragen »

lightedman wrote: post #55
kragen wrote: post #50

Earlier quoted context omitted.

The panel voltage is pretty stable until the illuminance gets really low (unless you're drawing a lot of current). Diodes such as solar cells are roughly constant-voltage devices. You can get a pretty long way avoiding filesystem corruption by mounting things read-only, but (I've heard) some SSDs aren't really read-only even when they're read-only, because of read disturb and the attempt to compensate for it in the F…

"The panel voltage is pretty stable until the illuminance gets really low" I'd like to see what panels those are, because the ones I've built while working as a PV manufacturing tech, both mono and poly (roughly 21% efficiency,) will have greatly varying voltages with even the tiniest hint of cloud cover over one cell, even with the junction box working to help separate out sections of the panel to maintain better vo…

Is that the MPPT voltage or the open-circuit voltage? I was thinking of a near-open-circuit voltage (which is what you have if you're powering a 2-watt webserver from a 50-watt solar panel), but MPPT will vary a lot more. Also, covering 6% of your cells will drop your voltage a lot more than covering all your cells 6%.

Re: How Sustainable Is a Solar Powered Website?

#60

Post by yjftsjthsd-h »

driverdan wrote: post #45
kragen wrote: post #16

Earlier quoted context omitted.

That is an excellent idea. With three or four servers they could entirely avoid batteries. I think you mean anycast, not multicast, but a less exotic option would be to use DNS failover, or even just round-robin DNS with no explicit failover: https://webmasters.stackexchange.com/questions/10927/using-m... https://www.nber.org/sys-admin/dns-failover.html

You wouldn't want to power directly from the panels without a battery. It would cause high instability on cloudy days, possibly leading to file system corruption.

Could you use a (big) capacitor then? Enough to smooth power out, but AFAIK doesn't degrade like batteries.
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