How to Build a Low-Tech Solar Panel? • Hacker News Board

Re: How to Build a Low-Tech Solar Panel?

#21

Post by saruken » Wed, Oct 06, 2021, 4:04 PM UTC

opwieurposiu wrote: post #17

zz865 wrote: post #11

Earlier quoted context omitted.

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?

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 clo…

Sounds neat! I'd like to read a writeup on your build if one exists.

Re: How to Build a Low-Tech Solar Panel?

#22

Post by technotarek » Wed, Oct 06, 2021, 4:06 PM UTC

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.

Re: How to Build a Low-Tech Solar Panel?

#23

Post by fwip » Wed, Oct 06, 2021, 4:18 PM UTC

ca98am79 wrote: post #13

johnklos wrote: post #4

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?

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?

Sure, if the economics 101 version of the efficient market hypothesis were true, that's what you might expect to see.

Re: How to Build a Low-Tech Solar Panel?

#24

Post by Kliment » Wed, Oct 06, 2021, 4:18 PM UTC

kamranjon wrote: post #8

gene-h wrote: post #3

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...

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.

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

Re: How to Build a Low-Tech Solar Panel?

#25

Post by squarefoot » Wed, Oct 06, 2021, 4:21 PM UTC

Syonyk wrote: post #20

Uninen wrote: post #5

"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.

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...

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.

Re: How to Build a Low-Tech Solar Panel?

#26

Post by colpabar » Wed, Oct 06, 2021, 4:24 PM UTC

technotarek wrote: post #22

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 sol…

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.

Re: How to Build a Low-Tech Solar Panel?

#27

Post by montalbano » Wed, Oct 06, 2021, 4:26 PM UTC

Syonyk wrote: post #20

Uninen wrote: post #5

"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.

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...

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?

Re: How to Build a Low-Tech Solar Panel?

#28

Post by [deleted] » Wed, Oct 06, 2021, 4:39 PM UTC

ca98am79 wrote: post #13

johnklos wrote: post #4

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?

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]

Re: How to Build a Low-Tech Solar Panel?

#29

Post by carapace » Wed, Oct 06, 2021, 4:44 PM UTC

johnklos wrote: post #4

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?

> 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

Re: How to Build a Low-Tech Solar Panel?

#30

Post by wonderwonder » Wed, Oct 06, 2021, 4:48 PM UTC

opwieurposiu wrote: post #6

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.

Interesting, mind if I ask the total cost for the system you made?