[HN Gopher] Working Off-Grid Efficiently
___________________________________________________________________
Working Off-Grid Efficiently
Author : zdw
Score : 234 points
Date : 2021-01-11 02:58 UTC (19 hours ago)
(HTM) web link (100r.co)
(TXT) w3m dump (100r.co)
| simonebrunozzi wrote:
| AWS' James Hamilton lives pretty much on a boat around the world
| most of the time [0].
|
| I was at AWS 2008-2014 and had a few chats with him. Super nice,
| very smart, humble. For a little while he used to be a car
| mechanic for Italian cars in his younger years.
|
| [0]: https://mvdirona.com/
| VBprogrammer wrote:
| If you found this interesting you will probably also enjoy having
| a read of Joey Hess' blog https://joeyh.name/offgrid/
| cesarb wrote:
| Joey Hess is also the author of git-annex (https://git-
| annex.branchable.com/), which helps with some of the things
| mentioned in the "Internet" and "Data Storage" sections of this
| article.
| hutzlibu wrote:
| I did this for years, but in the form of
| backpacking/hiking/cycling and still do it on occasion (when my
| family lets me).
|
| Meaning much bigger constraints in weight. 10 years ago, it was
| really expensive getting the equipment, I used a solar
| gorilla/power gorilla pack. Very nice, but also heavy. I think
| around 500EUR.
|
| Today I use 2 Anker 21 solar W and 3 power banks for half the
| price and at least triple the power. (downside is only USB
| charge, meaning not possible for many laptops, unlike the power
| gorilla)
|
| Also laptops really improved in battery life and power efficency,
| meaning, when I started doing it 10 years ago, I could only
| really work consistently, when I had a real power source nearby.
| Otherwise it was maybe 2 days of full-time working.
|
| Today I can work forever off the grid, on my cheap rugged Asus
| Chromebook, as long as the sun shines from time to time and I
| have a safe place to put up the solar panels. All in all my
| mobile office equipment is 4-5 kg. For short trips with laptop, 1
| panel and 1 powerbanks, cables,.. 2.5 kg. Which is managable,
| even when you carry also your tent and food.
|
| Combining working in nature really helps my creativity and I can
| recommend trying this out. The tech really is ready today, unless
| you want to do heavy video editing or 3D Design.
|
| But coding, in my case mainly with chrome dev tools and node,
| really works fine off grid. There are new insights to be gained,
| from top of a mountain, tree, or next to a river, compared to
| your never changing office wall.
| hutzlibu wrote:
| Bonus points from developing on slow hardware: you really have
| to code efficiently, as you notice, when something is going
| wrong and takes more time, than it should
|
| Also I now like the combination of computer with pen and paper.
| So sketching design things or algorithms on paper, before
| implementing them as code. (started doing so, to save batterie)
| djsavvy wrote:
| What kind of internet bandwidth/latency do you get? And how do
| you get it?
| hutzlibu wrote:
| Mobile connection obviously. The further remote, the less
| signal(usually). But most of my work can be done offline, so
| that is not an issue for me.
| gtirloni wrote:
| How do you manage(d) working with npm modules?
| hutzlibu wrote:
| My chromebook is in dev mode, so I can use chromebrew and
| just install npm. But I just use and do not create npm
| packages, so I don't know if theres a limitation there.
|
| (in theory I could boot a full linux in embedded VM, but that
| is too ressource intensive for my taste)
|
| In general, ChromeOS sucks, but the driver and firmware is
| really optimated, which means fast sleep/wakeup and long
| batterie life and with my basic tools running I am quite
| happy, even though my control over the system is much
| restrained compared to my manjaro laptop for example.
| jonmal wrote:
| Off-grid, yes, but no electricity, not for me. Thanks for sharing
| an interesting article though.
| pmlnr wrote:
| "off the grid" - except for the social media presence, the
| website, the cloud backups, etc which are all outsourced, on-
| grid, big power eaters. Articles like these always feel like
| Japan itself: clean, because all the trash and polluting industry
| was sent away to the rest of Asia.
|
| /me grumps away
|
| EDIT that said, there are good thoughts in the article, eg: "Hard
| copies: Paper is a stable and widely accessible material, unlike
| digital devices which are subject to breakages and obsolescence".
| I'll have to print a lot of photos one day.
| bob29 wrote:
| Don't forget the diesel, petrol, and propane. The dirty secret
| of most "off grid".
| ashkankiani wrote:
| Why live for years in the forest and write a book to be
| released afterwards when you can just show off how minimal you
| are in realtime? Thoreau would've just micro-blogged all of his
| thoughts on Twitter probably.
| gabereiser wrote:
| Why, when I got laid off due to funding, that I'm constantly
| reminded by my dream to set sail and work remotely. Dang it. This
| is my dream right here. Live off grid, conscious of my impact,
| and make a living doing what I love, being in the ocean.
|
| I bookmarked this under "Retirement goals".
|
| Whether it's an RV, a sailboat, a troller, doesn't matter.
| Housing is ridiculous and I'd rather spend my time doing
| something adventurous than sitting around waiting for the grim
| reaper.
| ConfusedDog wrote:
| I was just thinking about that... first thing come to mind is
| that I need StarLink satellite internet (said to have at least
| 100Mbps 20ms latency). Electricity wise, I'm not running server
| farm out there. Solar, wind, geothermal, even gas generators
| should be fine.
| Scoundreller wrote:
| Starlink draws about 100w without much variation unless you
| shut it off completely.
| beagle3 wrote:
| Probably a good thread to ask: A few years ago when looking for
| it, I was able to easily find deep-discharge 100Ah 12V lead-acid
| batteries at reasonable prices, which would have allowed one of
| my projects to go off-grid. However, what I couldn't find was a
| charge controller that would be able to reasonably e.g track
| charge and time. I didn't have the time and sufficient expertise
| to design such a charge controller myself.
|
| My options ended up being buy a pre-made, significantly more
| expensive UPS and pay for the up-down conversion loses; Or just
| used my 12V feed with no monitoring and hope for the best. I
| chose the latter, which ended up OK given this was a research
| project with a limited time horizon.
|
| Is the situation any better today?
| mastax wrote:
| There are many DIY charge controllers nowadays from aliexpress
| to commercial grade. I remember looking at them for LiFePO4
| batteries but almost all of them will support Lead Acid since
| it's just a few more lines of code.
| serjester wrote:
| Depends on the wattage but I just bought a 20 watt charge
| controller for $30. If you're just trickle charging a lead-acid
| battery that's plenty.
| driverdan wrote:
| I've been living mostly off grid for the past 3.5 years in a bus
| I converted. Solar isn't expensive anymore, panels can be had for
| <$1/Wh. The cost of batteries is still significant but some of
| that can be mitigated by buying used packs for 1/4 the price.
|
| The key with being off grid is redundancy. One is none and two is
| one. For example, if there are storms that last a week you'll get
| almost no solar power. You need another way to get power,
| typically a fuel-based generator.
| hinkley wrote:
| And you need to ventilate and supply that generator like it'll
| be running all the time.
|
| See also winter storms, where going outside is a lot more
| problematic than just getting wet.
| cameldrv wrote:
| Interesting article, but the extreme lack of electricity seems
| unnecessary, at least today. Solar panels have gotten much
| cheaper, enough so that generating adequate power to run a couple
| of laptops even on cloudy days is fairly affordable. Batteries to
| keep it going at night have also come down in price.
|
| Maybe the extreme power savings are more of an aesthetic thing
| for them.
| walrus01 wrote:
| On a medium sized sailboat the limiting factor for how much PV
| capacity you can have is the physical mounting space. Google
| "bimini top solar panel":
|
| https://www.google.com/search?q=bimini+top+solar+panel&clien...
|
| What could be trivially easy to mount on a small off grid cabin
| in the woods somewhere, like two of these:
|
| https://www.altestore.com/store/solar-panels/panasonic-hit-h...
|
| could be very difficult and too much surface area and wind
| loading on a sailboat that people can realistically afford to
| buy. If you have the space and can fit one, something like the
| Sunpower 400W rated panels which are composed of expensive,
| ultra high efficiency monocrystalline Si cells would be ideal.
| You're looking for the greatest ratio of watts per square meter
| in STC test conditions.
|
| What I would recommend is first calculating the watt-hours per
| day consumed by your projected load, versus what the PV system
| could be expected to produce.
| VBprogrammer wrote:
| Another factor in sail boats is the shading caused by masts,
| stowed sails, hand rails and lines. It's one of the few
| places where micro-scale wind turbines almost work.
| jarvist wrote:
| Sort of... but the wind turbines often don't point well
| when you're at sea, and you intentionally anchor in calm
| places to avoid the swell. Sailing specific PV would often
| have 40 silicon cells rather than 36 in series, to provide
| some headroom for partial shading. Watt & sea hydro-
| generators have become quite ubiquitous recently, as if
| you're making passage your entire vessel is a machine for
| concentrating wind energy:
| https://www.wattandsea.com/index.php/en/products/cruising-
| hy...
| hinkley wrote:
| Also you may be more likely to stay put on a calm day,
| increasing demand for power.
| guerby wrote:
| Why not floating solar panels attached to the boat?
|
| (Just a random idea, I know absolutely nothing about boats :)
| jcims wrote:
| I'm clueless in this area. Would a raft be viable? Presumably
| it would add some drag if you're underway but a small
| inflatable pontoon raft seems like it could run 4-6 panels
| and be reasonably portable when not in use.
| walrus01 wrote:
| I do off grid PV professionally but don't know a lot about
| boats. But having been on a few 42-48 ft size cruiser type
| sailboats, I can't think of a place you could easily pack
| away six 1.65x1.0 meter size (typical 60-cell) rigid,
| aluminum framed high efficiency PV panels, unless you
| basically dedicated the smaller guest bunk to storage
| space.
| 2Gkashmiri wrote:
| Hey. You said you do off grid. I have a question. I own a
| 5 kW on grid setup for net metering. Works fine but now I
| want to use backups. I have two options, either lithium
| 100ah 48v which is expensive or 12v 200ah x 4 to make
| 48v. Cheaper but limited life because the home load would
| be on it entirely.
|
| I dont know. The calculation of kWh checks out to be
| 100ah x 48v = 4800wh. And for lead acid 200ah x 12v x 2=
| 4800wh.
|
| What do you suggest or is there something I am thinking
| incorrectly... space is not an issue BTW.
| walrus01 wrote:
| google "DIY powerwall" if you're up for a bit of a
| technical challenge.
|
| 4 x 12V 200Ah isn't big enough for most houses, unless
| it's like a cabin in the woods somewhere. and you're
| right that the cycle life of those and cost is high.
|
| but commercial li-ion based solutions are also expensive.
| However, if you can keep them at 80-85% state of charge,
| and rarely if ever discharge them below 30%, they should
| have lifespans 5-6x longer than the lead acid solution.
|
| in either solution you can't really consider the full
| volts * Ah capacity of the battery to be usable. If you
| were to ever use all of the watt-hours in a 12V 200Ah
| battery you'd kill it, you never want to go below 20%
| state of charge... so to be conservative the actual
| capacity of a single battery is something like:
|
| 12 * 200 = 2400 Wh, then (2400 * 0.70) = 1680Wh.
| guerby wrote:
| Current LFP battery prices are around $120 per kWh
| delivered: I just ordered 14 kWh (48V 16S) for 1700 USD
| delivered.
|
| This is cheaper than an Apple laptop.
|
| A quarter of the price paid is shipping since it comes
| directly from China so source price is already under
| $100/kWh.
|
| A recent test by Will Prowse:
|
| https://www.youtube.com/watch?v=3U4ZfQ_IToI
|
| $433 280Ah LiFePO4 Cells Tested: Cheaper than lead acid!
|
| Many people have the same good experience with these kind
| of cells:
|
| https://diysolarforum.com/
|
| Added: 14 kWh will run a 20 Watt laptop for a month.
| walrus01 wrote:
| The part in that youtube video where he's using
| uninsulated steel wrenches across the top bus bars to
| tighten down the terminals is extremely scary.
| walrus01 wrote:
| Beware of suspiciously cheap lifepo4 batteries from
| China, they are by no means all the same.
| guerby wrote:
| If you look for known good chinese LFP vendors on forums
| it minimize the risk, lots of people are reporting to
| spec or very close to spec batteries. And when they are
| issues looks like most chinese vendors will just send a
| replacement if you document your problem well (compare
| this to local store return processes ...).
|
| But LFP batteries have gotten really cheap, so the price
| for a mistake is no longer prohibitive.
| driverdan wrote:
| Where are you getting new LFP batteries for that price?
| guerby wrote:
| Will prowse has a link to the vendor he chose in the
| youtube video description, if you search for "supplier"
| in the forum you'll get plenty of feedback on various
| known vendors.
|
| I chose one (after sending a few private message to forum
| members) but I'm not recommanding it until I get and test
| my batteries.
| bitxbitxbitcoin wrote:
| My dad gave me Will Prowse's book as a resource when I
| was rigging my van with solar - it was a great read but
| not a necessary buy because all the info you need is on
| his website.[0] His YouTube channel is a great resource
| that I'd definitely recommend! Interested to hear what
| the brand is if your tests turn out satisfactory.
|
| [0] https://www.mobile-solarpower.com/
| Peretus wrote:
| There is a fellow down in Port St. Lucie Florida that has
| launched a 100ah LiFePO4 with a 10-year warranty for ~
| $550usd each. I saw his shop in person when I purchased
| some solar from him and was quite impressed with the work
| they've done and the research and testing that has gone
| into their products. I had already purchased my batteries
| by the time I discovered his product or I would have
| purchased from him: https://outlandsolar.com/
|
| My partner and I live aboard a 41ft sailboat and both
| work remotely as programmers. I installed 1920w of solar
| on the boat and get approximately 3.5-4.5kwh per day in
| output, depending on which way we are oriented while at
| anchor. I installed 600ah of LiFePO4 batteries @ 12v and
| when combined with that amount of solar, we have pretty
| much all the power we need. We frequently cook with an
| air fryer and have a dishwasher on the boat that we run
| daily-- all off solar.
| cmason wrote:
| Where/how do you fit ~2000W of solar on your boat? That's
| impressive.
| Peretus wrote:
| I ended up mounting two ~39x70in panels on top of the
| davits and one on each side of the stern, mounted to the
| stanchions like 'wings' that can be propped up while at
| anchor. Strangely enough, I found I was getting so much
| power from the panels that I don't bother propping them
| up. Because of the way the panels are mounted (basically
| at least 1 panel facing the sun at all times), I'm able
| to get roughly 500w from 8:30am until just after 5pm. I
| was pleasantly surprised.
| driverdan wrote:
| That price is really good. I'm curious what cells they
| used.
| Peretus wrote:
| I'm pretty sure they're Sinopoly cells, but I'm no
| expert. The BMS they use is quite impressive too, from
| what I could tell. While I was there in the shop they had
| a battery cut open and I was able to see inside.
| mkingston wrote:
| The high efficiency panels are typically semi-flexible
| without the frame, are they not? Do you think it would be
| possible to obtain and mount them without a rigid frame?
| Or even to remove them from the frame? I'm asking partly
| because I had considered making some sort of basic,
| folding, portable solar panel structure- imagine a few
| semi-flexible panels duct-taped together. (I'd likely not
| _actually_ use duct tape).
| driverdan wrote:
| That's backwards. Flexible panels are less efficient than
| rigid ones.
| walrus01 wrote:
| Correct, flexible cells are 10-14% efficient, the best
| rigid monocrystalline single junction Si cells are 23%
| plus.
| mkingston wrote:
| I think that's correct for thin film panels. But it
| appears that monocrystalline panels can be manufactured
| with some flexibility. Hence my usage of the term "semi-
| flexible". Sunpower, for example, claims to produce high
| efficiency semi-flexible monocrystalline panels that
| would flex sufficiently for use on a bimini top, for
| example.
|
| It further appears that my statement "high efficiency
| panels are typically semi-flexible without the frame" is
| inaccurate- they are typically not reasonably described
| as semi-flexible, even without the frame and coating.
| walrus01 wrote:
| Real high efficiency monocrystalline si cells are not
| flexible in any way, for example the typical 156mm cell
| that makes up a 315-400W rated 60 or 72 cell panel. In
| fact they're quite brittle and fragile when not
| encapsulated on a backing sheet and under protective
| glass.
|
| Monocrystalline by definition is not flexible, you're
| referring to thin films (cadmium telluride or amorphous
| silicon or other)
| mkingston wrote:
| Thanks for the reply.
|
| Is there any middle ground?
|
| Is Sunpower's claim of 22-25% efficient monocrystalline
| semi-flexible panels not to be believed? Have I been
| fooled by the marketing? Are these thin film panels?
| Nothing I can find online suggests this is a dubious
| claim, but it's possible I'm simply failing to find
| correct information.
| znpy wrote:
| Congrats on reading the article and not getting the context.
|
| They live on a boat, by the sea, often in the middle of the
| ocean.
|
| Even with solar panel, extreme power saving is a necessity.
| Steltek wrote:
| More than that, they're on a sailboat! Electric motors offer
| regen when under sailpower, which is absolutely huge, or you
| can get a towable torpedo generator. Otherwise, get a small
| wind turbine.
|
| You can subsist on PV alone but there are far better options,
| especially when available PV area is so limited.
| pontifier wrote:
| I'm trying to run a company in a hostile regulatory
| environment. I've been without power since April 2020.
|
| This is in the middle of a city in the United States.
|
| I've tried generators and have gone through 3 so far. Fuel was
| very expensive, and the time and effort to keep them running
| 24/7 was miserable. I have now tried going solar but have had
| all sorts of problems with battery life and cloudy weather.
| It's not as easy as I thought it would be.
| pjc50 wrote:
| > I'm trying to run a company in a hostile regulatory
| environment. I've been without power since April 2020. This
| is in the middle of a city in the United States.
|
| .. how? Which city?
| InitialLastName wrote:
| This almost sounds like someone whose nightclub has had to
| go DL to ignore covid restrictions.
| pontifier wrote:
| Pine Bluff, Arkansas.
| quesera wrote:
| There might be a relevant distinction between "without
| power" and "power is not available to me".
| pontifier wrote:
| The city won't approve the electrical hookup to the
| building I purchased. I've had 2 different commercial
| contractors try to pull permits and both of them were
| denied. Not denied in writing, but convinced not to file
| the required application. I was actually assaulted by a
| zoning officer while sitting in their office trying to
| fill out an application they didn't want me to submit.
| quesera wrote:
| That sounds miserable. Fighting (an office of) City Hall
| is a painful experience.
|
| You must have some idea of why they are obstructing
| though, right? An electrical permit is an indirect block,
| so I'm guessing you've fought other battles with the
| office in the past?
|
| In any case, you have a right to file the permit. The
| office might make your life hell through documented
| denials or overzealous inspections, but getting the
| permit filed should be non-controversial. Once filed,
| they must approve or deny. If denied, there is a formal
| appeals process which can run through different
| people/departments. If you have the time and energy for
| it, of course.
|
| Anyway, I know you are not here soliciting advice, but my
| next step would be to bring a lawyer to the filing office
| to ensure that the application is filed, and that no
| further assault occurs. Good luck.
| InitialLastName wrote:
| I'm sorry I misjudged you, that sounds miserable.
| CaptArmchair wrote:
| > Solar panels have gotten much cheaper, enough so that
| generating adequate power to run a couple of laptops even on
| cloudy days is fairly affordable. Batteries to keep it going at
| night have also come down in price.
|
| From the article:
|
| > Our work schedule is tied to the weather, as we depend on
| solar energy to power our computers.
|
| So, what's the problem then? Well, they've written in-depth
| about the challenges and constraints of solar elsewhere on the
| site. [1]
|
| Their vessel is on the smaller side of the spectrum. There's
| only so much usable space to place a solar array. [2] They do
| use batteries and they have a small gas generator, but those
| are also limited and only used as a backup.
|
| [1] https://100r.co/site/off_the_grid.html#power [2]
| https://100r.co/site/pino.html
| fewrites wrote:
| Small wind generators at the top of the mast and a few other
| places might help.
| baliex wrote:
| What a beautiful website -- so inkeeping with their mission and
| ideas (this comes up quite often but, those dithered images
| really remind me of https://solar.lowtechmagazine.com/power.html)
| jerzyt wrote:
| It would be interesting how much power you could generate by
| having a little outboard propeller driving a small generator. It
| would decrease the speed of your yacht, but if you're not on a
| schedule to get anywhere who cares, right? Another option would
| be using Peltier effect, although I have no idea how efficient it
| could be. But sailing in the Polynesia, I'd think that there's a
| good temp difference between the water below the surface and the
| top of the boat.
| larrysalibra wrote:
| Hydro generators exist! They are relatively expensive for the
| small amount of power they generate:
| https://www.sailmagazine.com/diy/know-how-hydro-generators
| rtkwe wrote:
| They're not fool proof yet and can take a bit of tending
| unless you really spring for the top of the line.
| Particularly important is the blade pitch, on the more
| affordable models that has to be set manually and if you go
| too fast with an aggressive pitch intended for a lower speed
| you can break the unit very quickly.
| walrus01 wrote:
| What is a typical price?
| larrysalibra wrote:
| According to the article I linked, one that gives max 600
| watts costs around US$5000.
|
| The market is very small for hydro generators for
| sailboats.
|
| Solar is much cheaper because you can buy products that are
| targeted at mass market instead of only at sailboats.
|
| Source: I was recently purchased by a sailboat.
| tonyedgecombe wrote:
| _I was recently purchased by a sailboat._
|
| And what does your sailboat intend to do with its new
| purchase?
| tertius wrote:
| Take it for all it's worth!
| robszumski wrote:
| Suck his wallet dry is the usual goal I believe.
| hinkley wrote:
| Sailboats are very much like a reverse merger.
|
| The two happiest days of a boat owner's life: the day
| they buy the boat, and the day they sell the boat.
| ctdonath wrote:
| I run my "office" on portable solar much of the summer. Two
| takeaways:
|
| Solar averages ~10W/m^2 long term (days/weeks) with wild
| fluctuations. Getting easy reliable output retirees a lot of
| surface & batteries.
|
| When those storage batteries deplete, it's a hard stop.
| Recharging takes considerable time, competing for scheduled
| direct use. Plan on at least doubling panel surface just to
| recover from outages, and plan on more storage than you expect
| because long uncooperative weather happens more often, with more
| consequences, than you expect.
|
| Unless you are willing to shut down completely at times, or spend
| enormous sums, you must have a reliable on-grid source ... which
| then may as well be your primary.
| grecy wrote:
| > _you must have a reliable on-grid source ... which then may
| as well be your primary._
|
| Not at all.
|
| With net metering it makes sense to be on the grid during the
| day when you're making more power than you need, then if and
| when you need it you can pull power from the grid.
|
| In Australia my Dad got a 5kW system fully installed for $5k
| AUD, and he gets paid a few hundred dollars from the power
| company every three months now.
| ctdonath wrote:
| Problem there is, with enough customers doing the same,
| there's a great deal of idle capacity waiting to fill the big
| gaps. That's costly. Works fine now when solar is the anomaly
| (what I'm doing, plugging into grid when a prolonged storm
| depletes stored power), but keeping 100% of current grid
| capacity in unused reserve for 1% incidents (heavy clouds for
| >1 weeks) isn't practical. At some tipping point, classic
| grid power is driven out of the market ... and then an
| anomaly hits, with no grid to back into.
| SamBam wrote:
| I remember back in 1989 or so(!), my mom used to work at our
| summer cabin which had no electricity using a ~1m^2 solar
| panel, hooked up directly to a car battery, which was hooked up
| to a small laptop (a Compaq, I think).
|
| I have no idea if such a setup would be remotely feasible
| today.
| ctdonath wrote:
| Oh, it's feasible. That's close to what I'm fiddling with
| (just GoalZero.com products instead of bare car batteries
| etc). It's quite workable, but you have to be keenly aware of
| usage & limitations, and fiddle with stuff often (ex.: coping
| with passing shadows). Most people are expecting complete
| reliability - that's costly.
| ip26 wrote:
| Panels are better, MPPT are cheaper, and the right laptop
| uses hardly any power... I would think it should be more
| feasible in every possible way aside from increased
| expectations.
|
| A Surface Go averages something like 5W, and a 100W array can
| provide that in virtually all daytime conditions even without
| aiming.
| hinkley wrote:
| Additionally, the right laptop can use its internal voltage
| regulator to convert the 12-16 volts from the battery into
| the internal voltage.
|
| One of the secrets of the openwrt community was that those
| little linksys routers used a 9v power brick but the power
| regulator was still stable somewhere north of 12v, giving
| you a lot more options for repeaters or mesh networking.
| thinkmassive wrote:
| You could supplement with your own generator. Do you consider
| fuel to be an enormous sum, relative to solar?
| ctdonath wrote:
| I'm focusing on solar-only solutions.
|
| Once you introduce sourcing as cheap & reliable as fossil
| fuels back into the equations, dropping solar entirely
| becomes a rational solution as the frequency of solar
| "incidents" becomes apparent and non-FF mitigation costs
| soar. I find most people don't grasp how unreliable solar is.
| jimmaswell wrote:
| If you're intent on using solar anyway then I don't see how
| having a fallback generator would compel you to just give
| up on the solar. How often do you have to repair or replace
| panels?
| ctdonath wrote:
| It's just plain easier & cheaper to run FFs than solar.
| About the only serious disadvantage is noise.
| volta87 wrote:
| Where do you live ?
|
| You are making very bold claims about solar being
| unreliable, but I'd completely expect reliability of solar
| to vary significant from one location to another.
| ctdonath wrote:
| Southeast USA. On the whole a good place for solar. I'm
| trying to impress on people the many fiddly little
| obstructions that add up to significant reductions, and
| that despite prolonged good periods there are poor
| exposure times that fast burn thru stored energy and
| require substantial collectors to recharge in time for
| the next weather event.
| carapace wrote:
| Small-scale alcohol fuel production is an option. Grow
| sugar beets and make moonshine. It's still solar power. (No
| pun intended.) The molecules of alcohol are made of air and
| water and power from the sun.
| bitxbitxbitcoin wrote:
| A reliable, secondary source of power to account for
| consecutive days of bad weather doesn't need to be "on-grid."
|
| Most robust off grid setups that I've seen involve the use of a
| backup generator.
|
| For anyone considering an off grid mobile office in a van or
| other vehicle. When the sun isn't cooperative for too long and
| I find my storage battery being depleted too low, I simply
| start my engine and start charging the battery using my 12V DC
| cigarette lighter port.
|
| I have 200W of solar feeding a 100Ah 12V battery with an MPPT
| charge controller and I thought I had calculated enough
| redundancy to handle up to a week of bad weather, but end up
| using my alternator to charge when the sun is unreliable more
| often than I thought I would.
|
| PS: Are you using a PWM controller or a MPPT controller? The
| latter can increase efficiency by up to 30%.
| chrismorgan wrote:
| > _Solar averages ~10W /m^2 long term (days/weeks)_
|
| That figure surprises me. What I've heard before is that full
| sun is roughly 1kW/m2, and that over time you should expect to
| get 4-5 useful hours (depending on latitude and weather
| conditions of where you are--some will be outside this range on
| either side), so if you take 21% efficient solar panels, the
| total would be 1000 (watts) x 4 (hours) / 24 (hours) x 0.21
| (efficiency) = 35W.
|
| 10W is a lot less than 35W. I presume I have some incorrect
| assumption or am overlooking something.
|
| (I'm interested in this because I'm planning to build a
| velomobile and live out of it while going round Australia for a
| year. Power systems are something I've been putting a fair bit
| of theoretical research into, but I have no practical
| experience whatsoever. I've been planning to build solar
| panelling into the body.)
| ctdonath wrote:
| 35 is pretty close to 10 when you start at 1300 and prune
| obstructions.
|
| Now address clouds, angles, dust, snow, opacity,
| malfunctions, storage inefficiencies, panel aging, and
| chronic optimism. 10W.
| chrismorgan wrote:
| Most of that is what the 4-5 useful hours per day figure is
| supposed to take care of (that's a year-round thing, too,
| averaging summer, which may be as much as double that, and
| winter, which may be half).
|
| Hmm... storage inefficiencies? Are you including battery
| storage and perhaps an inverter in your calculations? I
| guess that'd account for some loss.
|
| I'm guessing also from "snow" that you may be in a place
| that gets comparatively little sunlight?
| adrianN wrote:
| 42,339 MW of PV installations produced 39,401 GWh of
| energy in 2017 in Germany[1], so about 38 days of peak
| generation, or roughly 10.5% of peak. A square meter of
| PV panels produces around 150W. So 15W average for a
| panel in a good location in Germany. 10W/m^2 seems like a
| good estimate if you want your stuff to work reliably
| year round. Better locations than Germany would do better
| of course, and restricting yourself to just summer
| probably helps quite a bit too (winters are dark and
| cloudy in Germany).
|
| [1] https://en.wikipedia.org/wiki/Solar_power_in_Germany#
| Statist...
| Retric wrote:
| Germany is north of Maine, it's a terrible location for
| solar power and heavily subsidized. At best they hit a
| capacity factor of 11.6% in 2018. By comparison the US
| had a capacity factor of 28% for utility-sized PV plants
| in 2015, but it's dropped as less efficient locations
| have been added.
|
| _A square meter of PV panels produces around 150W,_
| that's some low efficiency panels, you can easily hit
| 200+W /M2 using a high efficiency panel like SunPower
| Maxeon 3.
|
| Solar isn't a great fit everywhere. So, people really can
| see wildly different outputs from the same setup based on
| location. At 28% capacity factor averaging 60+W/M is very
| possible.
| gibspaulding wrote:
| I wonder if "4-5 useful hours per day" is per sunny day,
| so you can cut your number in half again for cloudy days.
| chrismorgan wrote:
| No, this is from averaging it across the entire year,
| based mostly on locations in the south of Australia
| (Gippsland, Melbourne, Adelaide, Ballarat, those sorts of
| areas), but I looked briefly at other parts of the world
| also. The idea is then that a panel rated at 250W can
| produce an average of about 1kWh per day when pointed in
| the optimal direction and never shaded (but without
| tracking the sun); the average winter day may get you
| only 500W, and the average summer day over 1500W, with
| plenty of variation within those seasons day by day also.
| hinkley wrote:
| The most shocking thing I ever learned about solar panels is
| that they behave as a rectifying diode when they are not
| receiving sufficient photons.
|
| That means you can screw up the current from an entire bank
| of solar panels by having just one of them in deep shade. So
| if you want maximum generation, you either have to site them
| in a very clear area, or wire them all in parallel instead of
| serial, which means much fatter wires to reduce transmission
| losses, and then larger conversion losses?
| senkora wrote:
| I learned this at the Exploratorium in SF. They had an
| exhibit consisting of a miniature solar panel with an
| output reading and a small token that could cover a single
| panel. Very fun trip!
| nanomonkey wrote:
| One way around this is to utilize cheap micro-inverters on
| each panel. This makes it easier to add new panels as your
| usage goes up (or funds). Also easier to monitor their
| performance due to shading, dust, etc.
| yardie wrote:
| I don't think this is the case with newer panels. Our boat
| stern mounted panels atleast had one panel shaded at
| anytime. The output drop was proportional to the area
| shaded. The bigger losses came from the angle of the sun.
| Output was mostly logarithmic, almost nothing at
| sunrise/sunset, full output at 12pm, 50% by 3pm.
| PaulDavisThe1st wrote:
| It's still true of the cells in the panels. But it's
| typical these days to add a device between the panels and
| the DC circuit than can improve the situation (e.g. by
| cutting the panel out of the circuit if it isn't
| productively contributing the array's generating capacity
| at the moment).
| hinkley wrote:
| So the problem should be corrected at the panel level,
| but still exists at the cell level?
| PaulDavisThe1st wrote:
| Yes, the diode behavior is (I believe) a fundamental
| property of the cells.
| organsnyder wrote:
| I'm not sure on the details, but according to my solar
| installer newer panels (or inverters or some other
| component) are no longer susceptible to this.
| chrismorgan wrote:
| The key term with this is _bypass diodes_. Not all panels
| will be equipped with them (which puzzles me, given the
| substantial benefit and what I imagine to be near-trivial
| BOM cost).
| leokennis wrote:
| Not qualified to comment on any technical aspect of this. But
| this observation:
|
| > "Living and working aboard a sailboat was for us a constraint,
| it liberated our imagination by eliminating possibilities."
|
| Rings very true to me. When you're in a tent in the woods,
| without mobile internet and just human company for
| "entertainment", it's incredible how easy it is to have long
| conversations or to think/make up games to pass the time.
| eigenvector wrote:
| Indeed. I've had the good fortune to pass long periods of time
| (from days to months) hiking and it's amazing what
| entertainment just meeting a new person after weeks can
| provide. And no matter what book you bring along, you will
| finish it in a couple days without constant distraction.
| Havoc wrote:
| Being that internet and power constrained would just stress me
| out frankly. One more thing to manage...
| VBprogrammer wrote:
| The author makes the claim that these constraints lead to more
| creativity and perhaps focus. I mean we both probably wouldn't
| be here if we knew we only had one hour of battery power for
| the day.
| throwaway981374 wrote:
| It's pretty amazing that the article and the whole comment thread
| neglect OSes.
|
| I use Debian with i3 on a 10 years old laptop with 4GB of RAM.
| It's my only workstation and I'm a software engineer.
|
| I usually run two browsers including a tab for slack. Everything
| works fine.
|
| Tip: install the documentation OS packages for all the libraries
| you need and also read manpages. Works well when you are on
| planes often and makes you a better developer than relying on
| search engines.
| horsawlarway wrote:
| I'm not really sure I understand. Most modern laptops are much
| more power efficient than older models.
|
| If you're really looking to save watts, and ARM chromebook is
| pretty hard to beat.
| throwaway981374 wrote:
| I'm providing an example on how efficient software can run on
| limited hardware resources.
|
| I'm not advocating for old hardware. ( _facepalm_ )
|
| More tips: use powertop. Use CLI-based stuff. Download email
| locally in bulk/batches.
|
| Don't use software that does home-calling or any other
| unnecessary network traffic.
|
| 1 large monitor is more efficient than a dual screen setup
| flobosg wrote:
| I've been following Hundred Rabbits' Rekka[1] and Devine[2] for a
| while. Their sites are full of interesting tidbits on different
| topics and projects. If you liked the article I recommend having
| a look at them.
|
| [1]: https://kokorobot.ca/site/home.html
|
| [2]: https://wiki.xxiivv.com/site/home.html
| PaulDavisThe1st wrote:
| I've lived for extended periods (up to 9 months) in my self-built
| Sprinter, with 550W of panels on the roof, and 455aH of battery
| inside. That system runs the lights, the fridge, the toaster, an
| electric kettle, the heater fan/pump, water pump, a 40W audio
| amp, and my purpose built computer.
|
| The computer is a mini-ITX i7 quad core, with a "micro power
| supply" that lets me plug it (almost) directly into my batteries.
|
| Things I've learned:
|
| 1) you can't plug directly into the batteries if you've got a
| smart solar charge controller. That will sometimes take the DC
| circuit voltage up to levels that the micro PSU considers unsafe,
| and the computer will shut down. I had to add a voltage regulator
| to keep the DC V levels seen by the computer (and other
| equipment) within range. My Morningstar charge controller will
| lift the DC V to 14V fairly often if there is a lot of sun and
| the batteries are moderately discharged.
|
| 2) Monitors are a problem. Some years ago, you could find
| monitors that accepted a standard 12VDC power plug fairly easily.
| Then someone figured out how to shrink the monitor PSU (thanks,
| Apple!) and they vanished inside the monitor case. You now have
| to hunt really hard to find anything that is 12VDC native. This
| is another argument in favor of laptops.
|
| 3) Native (desktop) software development is a totally different
| ballgame than webdev for this scenario. As I mention a lot here
| on HN, compiling my software is a major issue no matter whether
| I'm grid connected or not. It takes time, and it takes power. It
| actually takes _more power than the refridgerator_. If you 're
| going to just "be online" all day, or just working in the cloud,
| or just pushing data to and from the cloud, you don't need much
| power (my setup would last for 4-5 days of that kind of work. But
| if you're going to be compiling code (i.e. 100% CPU utilization)
| for extended periods, you need a lot of power. That means panels
| and/or batteries.
|
| 4) Laptops offer more power flexibility in part because they have
| their own batteries. You can get them fully charged during peak
| insolation, which doesn't take long, and then allow the remaining
| sun to keep charging your main batteries. Sometimes you can get
| another charge into the laptop batteries before sundown, giving
| you another nice blob of energy to use in the dark. You can also
| use them outside the vehicle, which for some people is important
| (it isn't for me, in general)
|
| 5) I experimented in the beginning with a wifi antenna on an
| extensible mast. It connected to an internal router (also
| directly powered by 12VDC from the batteries/voltage regular). I
| gave all that up fairly quickly. Open wifi worth using is
| vanishing rare (thanks, telecoms). I ended up with a Verizon
| jetpack (grandfathered into an unlimited 4G data plan for
| US$70/month) and use that exclusively. It has been really great,
| generally even better than trying to use the wifi when we stay at
| friends/family.
|
| 6) in the not too distant future, I will switch out my aging AGM
| (lead-acid, but better) batteries for lithium ion, which will
| effectively double the size of our battery store (Li batteries
| can be fully discharged)
|
| 7) smart charge controllers are great for battery life but
| terrible for power collection. They will (correctly) limit the
| current to the batteries based on their current charge level,
| tapering off as the batteries near full. This can lead to
| situations where there is full sun available all day, but it
| still takes hours to get back to 100% because the charge
| controller is being careful and looking after your batteries.
| This is good for longevity of lead-acid batteries, but
| infuriating if you need to "bank" the power as fast as possible
| (e.g. its going to be cloudy this afternoon). This issue, IIUC,
| goes away with Li batteries, which are happy to accept about as
| much current as you can give them (they just need to be above
| freezing).
| chrismorgan wrote:
| I'm planning to build a velomobile (and trailer) and live out
| of it for at least a year. One of the things I've been mulling
| over is computers, as I'd like to build or buy a new computer
| at some point in the not-too-distant future to replace my
| current dying laptop. How much power does your Mini-ITX machine
| use when _idling_? And have you tried to optimise it down?
|
| I've been thinking of things like the AMD Ryzen 9 5950X,
| shutting down most of the cores when I want to conserve power
| in addition to severely underclocking it a lot of the time, but
| so that at times when power is more readily available or if I'm
| compiling lots of stuff, I can go all out.
|
| I see figures for the last few generations of desktop
| processors of the whole machine using something like 50W when
| idling.
|
| Meanwhile, I see a laptop with a 49Wh battery and an AMD Ryzen
| 5 4500U advertising ten hour battery life for a web browsing
| workload--which means that it's averaging 5W for the computer
| _and_ screen, when doing even a little bit more than idling.
|
| So then I think, these desktop computers can't _actually_ be
| idling at that much power, right? That's over a kilowatt hour
| per day if left on full time! Or at least, there must be some
| way of instructing them to use far less power, like a laptop
| would? (It's a long time since I've dealt with a desktop
| computer to the level of knowing about power consumption.)
|
| I'd love the power of a top-end desktop processor and to pair
| it with a carefully chosen and placed screen, but if that means
| an extra 50W or more of drain while it's on, I might need to go
| with a laptop to make it through the winter.
|
| (Many DC-ATX power supplies wouldn't deliver enough power, but
| I believe https://www.mini-box.com/M4-ATX, rated at 250W (300W
| peak), should be just barely sufficient for a typical machine
| with any of AMD's 105W CPUs, like the 5950X, and a 60-75W GPU
| like the AMD Radeon RX 560 (as powerful as you get before
| requiring an external power connector, which I haven't spotted
| a DC power supply supporting, though I haven't looked too
| hard), at full load. But slightly reducing the envelope of the
| CPU or GPU would probably be a good idea.)
|
| Perhaps I should ask Metabox for details about
| https://metabox.com.au/store/Prime-Ai-Range (from the Clevo
| ODM) and what power it uses when idling. I've never seen a 230W
| AC adapter before!
| PaulDavisThe1st wrote:
| I never tried to "optimize it down", because I essentially
| always had enough power (and on the very rare occasions that
| I did not, I just stopped working).
|
| Laptop battery life is only accurate if you do typical
| consumer laptop-y things. If you develop native desktop
| software or edit video (maybe even audio) all day, those
| numbers are impressively optimistic.
|
| I believe my mini-ITX system is rated 160W TPU. A full quad-
| core sustained compile would pull about 12A DC, or about
| 140W, but that included the monitor, voltage regulator and
| 40W audio amp. At idle, the same setup would pull about 2-4A,
| or 24-48W.
| PaulDavisThe1st wrote:
| Just for reference, my van system has one of these inside:
| https://www.mini-box.com/picoPSU-160-XT
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