[HN Gopher] How to Build a Low-Tech Solar Panel?
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How to Build a Low-Tech Solar Panel?
Author : danielg0
Score : 159 points
Date : 2021-10-06 09:30 UTC (13 hours ago)
(HTM) web link (solar.lowtechmagazine.com)
(TXT) w3m dump (solar.lowtechmagazine.com)
| jakedata wrote:
| https://solar.lowtechmagazine.com/power.html
|
| The website is powered entirely by solar and is currently
| consuming 2.44 watts. With that massive power consumption they
| are probably mining bitcoin too.
| ljf wrote:
| 2.4w? My led bulbs use 4w - I doubt you could mine much bitcoin
| with that low a power?
| dmos62 wrote:
| I really enjoy this magazine.
| technotarek wrote:
| My father and I built a solar powered dog house heater in the
| 80s. We got the idea and plans from a Detroit area newspaper. The
| "cell" was simply plywood painted black behind a piece of glass
| with room in between for air movement. It successfully raised a
| fully sealed box (perhaps almost 1sq meter) to 40 deg C in the
| dead of Michigan winter. It also got me a blue ribbon at the
| science fair. I've been intrigued by solar power ever since, but
| only in terms of tracking the science progress.
| colpabar wrote:
| This is pretty cool on its own but the fact you did it before
| the internet using _a newspaper_ is very interesting. I really
| struggle to imagine how I 'd do anything without looking
| online.
| jimmyswimmy wrote:
| There used to be bookstores and magazine shops. I don't quite
| mean to say these no longer exist outside of airport waiting
| areas but they were ubiquitous. Libraries were a source of
| knowledge rather than a place to get free wifi. Wikipedia's
| predecessor came as a shelf of books.
|
| This sounds snarky but I don't mean it as such. It's what was
| available and how much knowledge was passed around. It wasn't
| hard to learn about even esoteric things if you had a good
| library. It was hard to find more than one such book though,
| so there wasn't as much opportunity for expansion of
| knowledge by comparing approaches.
|
| I like the internet age better though it has become more
| challenging to separate fact and fiction. The library didn't
| have too many fake science books.
| pjc50 wrote:
| > The library didn't have too many fake science books.
|
| As a kid, I found the UFO section of the library and read
| all kinds of interesting and almost certainly not true
| things. It was conveniently next to the programming books
| ..
| ghaff wrote:
| Ay one level, obtaining knowledge was _different_. You went
| to libraries--assuming you had access to a good university
| or city one--and good bookstores, which were also somewhat
| limited outside of major cities. You called people or wrote
| them letters. Etc.
|
| It was however also just harder and more limited. I
| definitely had projects in school that required looking
| through the library stacks and probably ended up with more
| "winging it" and depending on one or two old sources than
| would be the case today.
| vmh1928 wrote:
| Pre-internet people subscribed to specialized periodicals.
| Home Power and Mother Earth News were two. Both were filled
| with case studies and DIY projects and the back pages had
| "send $5 for plans to build your own low-head hydro." I'm
| sure there were more publications (Stewart Brand's
| publications come to mind, Whole Earth Catalog and
| CoEvolution Quarterly for two.) The archives of Home Power
| (1987 - 2018) are here: https://www.homepower.com/
|
| Popular Mechanics and other "Popular xxx" magazines are
| also examples. If you were lucky your local library
| subscribed so you could read them there (hopefully people
| hadn't stolen the issues or ripped pages out.)
| drewcoo wrote:
| Or if you couldn't find it in a library, you could call a
| librarian: company, city, university, or otherwise.
|
| I enjoyed the film Desk Set. Katherine Hepburn is one of
| those librarians, working at a pseudo-NBC company in the
| 50s. (As a special bonus, it features early movie mainframe
| hijinks.)
|
| https://www.rottentomatoes.com/m/desk_set
| ivankolev wrote:
| A little on a tangent, but I've been thinking that it might
| be valuable to keep this offline knowledge infra around for
| backup, afaik properly stored book has lifespan that is
| still an order of magnitute longer than any digital
| storage.
| [deleted]
| ghaff wrote:
| It's a complicated question.
|
| On the one hand, barring natural disaster/fire/water
| leaks/etc., your library book will last a good long time
| --at least until the library gets rid of it because they
| need the space and no one's checked it out recently. On
| the other hand, even with inter-library loan, it's not
| super-accessible especially if it's in, say, a private
| university library. And if something does happen to it,
| it's gone.
|
| On the other hand, a single digital copy won't last as
| long. But subject to a lot of factors and caveats, copies
| of that digital artifact can last indefinitely.
| phamilton wrote:
| I did something similar with a solar oven. Painted a mason jar
| black and then used aluminum foil to build a concave reflector.
| It worked ok, but I was able to get water above the
| pasteurization point (160* F).
| black_puppydog wrote:
| I've been working on my parents to put this thing in their
| garden: https://frank.geekheim.de/?p=2476
|
| I'd do it myself but I'm a city dweller with not even a
| balcony... :|
| jhallenworld wrote:
| Young me went to a solar exhibition at Brookhaven National Labs
| around 1978 or so. They had an electric car (maybe the
| Electrovette?), photo electric panels and outside someone
| showing how to make a forced air solar heater. It was an
| insulated box with a glass or plexiglass window to allow light
| in. Inside was an array of cut up soda cans, all painted black.
| A port for air inlet and a port for outlet and voila.
|
| [I'm pretty sure this was in BNL's old graphite research
| reactor building, which was open for tourists. I've since
| learned that this was an air-cooled reactor like the one in the
| famous UK Windscale accident, and that it has now been
| completely disassembled.]
|
| Solar was big then- I remember a talk about it at the local
| library also. People were making parabolic solar hot-dog
| cookers.
| SV_BubbleTime wrote:
| I assume you took this down in the summer? Or you had a dog
| oven?
| gene-h wrote:
| It's a cute approach, but perovskite solar cells can probably do
| much better. Perovskite solar cells can be made at close to room
| temperature, use relatively common elements, and can be made
| fairly thin. The current efficiency record for perovskite solar
| cells is 25.6%[0].
|
| [0]https://www.pv-magazine.com/2021/04/06/unist-epfl-
| claim-25-6...
| vamin wrote:
| Perovskites break down when exposed to moisture, so while I do
| think you could DIY a solar cell pretty easily, it wouldn't
| last long. There are ways around the moisture problem, but
| they're not so easily DIYable. "In particular, water promotes
| fast decomposition, leading to a drastic decrease in device
| performance." [0]
|
| [0]https://www.nature.com/articles/s43246-020-00104-z
| kamranjon wrote:
| The purpose of the article was to explore diy manufacturing of
| pv cells. I don't think this korean/swiss collaboration on high
| efficiency perovskite solar cells is within the reach of your
| backyard fabricator.
| Kliment wrote:
| Perovskite cell manufacturing is quite DIYable. There's been
| several experiments (lab-scale, not industry-scale) with
| making the lead-based perovskite film from waste with very
| minimal equipment. The main problem is toxicity, both to
| people handling it and to environment if disposed of
| improperly. Example:
| https://www.youtube.com/watch?v=oQ2bz6jlbz0
| [deleted]
| Kliment wrote:
| Yeah, that's a really promising material for both efficiency
| and manufacturing cost. It's unfortunate it's so toxic.
| aclarry wrote:
| The title made me think of my final first year chemistry lab
| where we made dye-sensitized solar cells from raspberries. It was
| an incredibly low-tech process aside from the conductive oxide-
| coated glass slides used as the electrodes. I'd love to see an
| in-depth guide on this solar panel design.
| johnklos wrote:
| Why is it never surprising when we hear stories like how Edison
| bought a thermoelectric generator company (Clamonds's Improved
| Thermopile) and ceased development.
|
| How much human progress is hampered by the desire of some to
| profit, no matter the cost to the world?
| ca98am79 wrote:
| If it were really that valuable to human progress wouldn't
| another company or competitor to Clamonds's Improved Thermopile
| become extremely profitable and valulable?
| [deleted]
| jandrese wrote:
| It might have been patented. By the time the patent runs out
| the alternatives have become standardized and refined enough
| that the original can't compete.
| c54 wrote:
| Unfortunately no, there's no law of nature which says
| companies/competitors will appear to serve this kind of
| function.
|
| Mostly bc short term profit maximization can be thought of as
| a greedy optimization which is blind to long term gains. This
| is why the tragedy of the commons happens
| mjmahone17 wrote:
| Maybe? But sometimes people don't see "obvious wins" for a
| very long time.
|
| Look at Musk's electric car story: there were a variety of
| electric cars that companies killed off (like the EV1) years
| earlier than the Tesla was released. It's unclear if anyone
| who had the capital would have seriously entered the space if
| Tesla as a company did not exist. Maybe we'd be exactly as
| far along, but there's a good chance the lack of "electric
| car infrastructure" and internal company incentives would
| basically keep anyone from going far enough before killing
| their project.
|
| When the path to profit is only a short journey from where we
| are now, you're right that some other company will probably
| adopt it. But add two or three hard steps that they need to
| overcome first, and it's pretty common for human progress to
| stagnate in a local maxima for a long time.
| vsareto wrote:
| >If it were really that valuable to human progress
|
| The issue here is resting that value judgment on a small
| number of people (in this example, one person: Edison) to
| determine if it's valuable to human progress. They could be
| malicious or simply wrong about their estimation.
|
| But also, no, markets aren't efficient, so they won't
| necessarily be correct on value-for-human-progress.
| fwip wrote:
| Sure, if the economics 101 version of the efficient market
| hypothesis were true, that's what you might expect to see.
| pjc50 wrote:
| I've not heard that one. I've heard of Edison hiring the mob to
| beat up competing film companies; that's why Hollywood is on
| the west coast, to get away from him.
| https://www.saturdayeveningpost.com/2021/03/thomas-edison-th...
|
| (thermoelectric generators have pretty terrible efficiency,
| though)
| carapace wrote:
| > Purportedly, the unnamed inventor of flexible glass (vitrum
| flexile) brought a drinking bowl made of the material before
| Tiberius Caesar. The bowl was put through a test to break it,
| but it merely dented, rather than shattering. The inventor
| repaired the bowl easily with a small hammer, according to
| Petronius. After the inventor swore that he was the only man
| alive who knew the manufacturing technique, Tiberius had the
| man executed. He feared that the glass would devalue gold and
| silver, since the material might be more valuable.
|
| https://en.wikipedia.org/wiki/Flexible_glass
| agumonkey wrote:
| universe doesn't follow a straight path to optimal.. only
| locally optimal bits.
|
| what if ICE never took off and we spent 100 years developing
| electric vehicles ?
| jandrese wrote:
| WWII would have looked very different, especially the
| aircraft. Naval warfare would have looked nothing like it
| did. Well, maybe naval boilers wouldn't be counted as ICE,
| but even if you allow for that it likely means no oil based
| infrastructure so everybody is still shoveling coal. Even
| that relatively small change makes a big difference.
| Uninen wrote:
| "This website runs on a solar powered server located in
| Barcelona, and will go off-line during longer periods of bad
| weather." - https://solar.lowtechmagazine.com/power.html
|
| What a lovely idea.
| Syonyk wrote:
| They've done some analysis, it's not really that clean, once
| you count embodied energy.
|
| https://solar.lowtechmagazine.com/2020/01/how-sustainable-is...
| squarefoot wrote:
| True, but...
|
| From the server's data: Power used 2.62W
|
| With these figures they could easily rely on used solar
| panels and batteries, therefore adding nothing to the
| environmental cost of building new ones and reducing the
| impact of recycling them by increasing their active life.
| Gradual repurposing of used cells and batteries to less
| demanding uses should be always considered before sending
| them to recycling. I do this all time with normal batteries,
| including non rechargeable ones such as alkalines: a battery
| that can't supply a toy with motors anymore will likely work
| in a small radio, and the one which is becoming too weak to
| supply a radio can work for some months in a TV remote.
| montalbano wrote:
| Embodied carbon is amortised over time, and is not considered
| for the Spanish grid comparison, as noted in the article,
| unless I missed it later on?
| gknoy wrote:
| I realize this is almost completely off-topic for the article,
| but I really like the way this website communicates the
| server's charge levels with color and indicators as a percent
| of the page's visible area.
| kitd wrote:
| I feel a backup wind generator could solve much of that
| problem.
| Faaak wrote:
| An extra solar panel would be cheaper per w I'm pretty sure
| foxhop wrote:
| After school, my son Carter and I explored engineering, science,
| and math, with our first experiment:
|
| Attaching a Bilge Pump to a 100 watt solar panel. The Setup Could
| move Thousands Gallons of Water Off Grid!
|
| Reference: https://youtu.be/E9Ea2n1vryo
| opwieurposiu wrote:
| I put some used PV panels on my shed's roof and wired them up to
| the bottom element of my electric water heater. This cut my
| household electric use in half. Not connected to the grid so no
| expensive permits needed.
| abraae wrote:
| I was thinking to do this but I had some concern about
| electrolysis, as electric water tanks are designed for AC, not
| DC.
|
| But I never learned if this was a real concern or not.
| opwieurposiu wrote:
| In north america both terminals of the heating element are
| galvanically isolated from the tank, so this is not an issue
| if the wiring is installed with due care.
|
| In countries like brazil and germany that allow "bare wire"
| heating elements you might have trouble with the tank lining
| plating onto the element or visa versa.
| abraae wrote:
| Thank you! I will check the regs for my country.
| wonderwonder wrote:
| Interesting, mind if I ask the total cost for the system you
| made?
| turtlebits wrote:
| This is would be fairly inexpensive to do. DC heating
| elements are < $40 and used panels can be had for ~0.20$ a
| watt or less.
|
| You'd wire the PV panels directly to the heating element. (Of
| course you'd have to size your element to match the
| volts/amps of your panels)
| opwieurposiu wrote:
| The materials cost was about $1400, half of that is the
| panels the rest is wire, conduit, brackets, etc. A solar
| permit in my area costs $1200+ . The high permit costs would
| make a system this small uneconomic. Local codes vary but in
| my jurisdiction I could avoid need for permit by putting the
| panels on my shed instead of my house and using the power for
| the water heater instead of connecting to the grid.
|
| The payback is 3-6 years depending on what ratio of peak/off-
| peak power pricing you assume.
| wonderwonder wrote:
| very cool, thank you. Payback is also hot water when the
| power goes out :)
| zz865 wrote:
| Yeah I wish there was more of this happening. BTW what happens
| when your water is fully hot and the sun is shining - does that
| panel detect there is no load so doesn't generate?
| simplicio wrote:
| Presumably over-shooting to some degree in the middle of the
| day is good, since it provides a cheap form of energy
| storage.
|
| Obviously you'd want a cut off at some temp though, for
| safety concerns.
| opwieurposiu wrote:
| There is no thermostat for the PV panels. The summer power
| output of the panels comes into equilibrium with the heat
| loss of the tank at 80-85C. I did add a 93C thermal fuse to
| augment the safety of the PTV value.
|
| I have a mixing valve on the output of the water heater to
| mix with cold down to about 50C. This lets you get around 2x
| the nameplate capacity of hot water out of the tank so there
| is enough to bridge a cloudy day.
|
| To get the full capacity of the panels, it necessary to
| choose a water heater element that matches the source
| impedance(Vmpp/Immp) of the solar panel array.
| saruken wrote:
| Sounds neat! I'd like to read a writeup on your build if
| one exists.
| foxhop wrote:
| Sorta related if you don't want to hack that sort of thing
| yourself -
|
| Hybrid Hot Water Heater Saves 69 Percent On Energy Consumption:
|
| https://russell.ballestrini.net/hybrid-hot-water-heater-save...
| smaddox wrote:
| This is quite fascinating, if true. Having studied solar
| photovoltaics fairly extensively in both undergrad and grad
| school, I'm a bit skeptical that he achieved such efficiency with
| such a simple design, but it's not completely impossible.
|
| It's important to note, though, that most of the cost of present
| day polysilicon solar cells comes not from the semiconductor
| device and contacts, but from the module and supporting
| electronics. So trading cell efficiency for cost will actually
| degrade overall installation cost per watt (since you'll need
| more of the more expensive parts), AND increase the amount of
| land required.
| jvanderbot wrote:
| This is such a simple thing to test and write up as a business
| plan. My oven doesn't go to 500C, but from the description it
| does sound like a simple factory process could produce these.
|
| I'd work on this.
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