Anyone Seen Usefull Solar Panels Around?

[Polossatik]

I did a search here on the forum but found not much usefull information.

Most links where to a old soldius device or thing like this.

Who looked to me something that might be barely usefull...

I'm not talking about stuff like this thingy

or this thingy.

Seen above linked stuff only put out a measery 80mA ( and that's "max") or so it will take day's, if not a week to charge a 4000mA battery device... Hence that thing not very useful. The build in 1000mA or so battery is also not really "hot" imho.

But a panel with a bit more "juice" (and maybe without a build in battery) may be nice...
So has anyone come across a nice solar panel with some decent output (like 300/400 mA max @ 5V regulated ) ?

edit: adde some pics

 

[gruso]

http://usb.brando.com.hk/prod_detail.php?prod_id=00304

Previously posted in this thread, but that discussion kind of went to crap.

 

[Polossatik]

..
Previously posted in this thread, but that discussion kind of went to crap.



yeah, I found it there. But seen most solar discussion went "into crap" I'm just trying it one more

Searching further It looks like the only thing around is one of these Backpacks with solar panels....

There must be some kind of similar setup without the back pack itself?

edit: Doh - oke, you can order the panels separately... Cool: let's try to find similar panels as these specs.... And then a battery (or a spare Pandora battery??? - ) as buffer with a nice low power LM voltage regulator... hum....

edit2: Solar gorilla, aldo a bit pricy (137 £) and rather big this beauty has 500mAh @ 5V

Edit3: cheaper one: (106 euro)
High Capacity Solar Charger Battery

This has even an "Ultrasonic Mosquito Speaker: Emits high pitched frequency sound to repel mosquitoes".. lol
hum according the specs it's a "Capacity: 20000 mAh (74W/h)" thing... 20000 mAH battery for that price included? I don't buy this...
edit4: from NL reseller site "Accu capaciteit: 20.000mAH " right... and santa is also coming this year.
Seen it suppose to charge in 3 hours using 18v/2000mA that's 108w you pump into the thing... assuming it's also an 18v battery inside, and assuming 1.2 V for good old NiCad's that's around 15 cells, each around 4000mA...which seams more realistic....
so the max mA rate for the solar panel would be around 1/3 of the AC charger, so around 650mA...
to bad it's so damn big.

 

[ledow]

Yeah, that's the problem with solar - anything that does something useful is usually too large and expensive for the job you need it for.

I bought a "cheap" panel from Maplin's once to test some ideas out that I was having and I knew solar was a bit of a waste of time but I was more interested in how well it worked than an actual finished thing that I was building.

For £30, I got about 17v and about 100mA (advertised as 1.5W, but you only got that in SERIOUS sunshine when the panel was directly angled at the sun on days when the sun would literally burn you and make the panel so hot that you couldn't angle it with your hands). At that rate, charging a 4Ah (4000mAh) 5v battery would take... about an entire day's worth of power, not including quite a lot of losses and variation on the way. Solar is EXTREMELY inefficient. Even my garden lights with the tiny solar panels can only do an hour or two of lighting a tiny blue LED after an entire day's worth of charging.

http://www.maplin.co.uk/Search.aspx?criter...r&source=15 shows you some of the options available. To be honest, if you think you'll charge a Pandora or similar device from solar within the next five years without carrying around something which folds out to at least as big as an A4 piece of paper and several HOURS of top-quality sunlight to charge, then you've not done the mathematics.

Those ones you put on the roof to power your house? Unless you buy lots of the absolute top-of-the-range ones, have them fitted properly, live in a 100% top-quality sunshine area and have an extremely energy-efficient household you will NEVER save more electricity than they cost. It's not just solar at that scale, the same goes for wind turbines as well.

If you want to know how much power you are actually pulling, try and draw enough current from a handheld-crank charger mechanism (like the wind-up torches etc.) to do the same job. Even if you factor in, say, a 50% loss (i.e. you "imagine" you get twice what you actually do), you'll quickly realise that you are talking about a lot of energy. The only practical way to achieve that at the moment is with a good old electrical socket or a high-density battery charged from the same. In fact, by the time solar becomes "mainstream" for such amounts of power, it'll be obsolete. You're more likely to be able to use a supercapacitor instead of batteries by that time.

 

[Polossatik]

cheers ledow,
that links seams to have some nice things on list...

It indeed looks like you say that all those power ratings are based on MAX output possible, hence totally useless in northern country's

Looks like you're at least spending 100 euro on panels alone to have around 400mA around 6-7 volts on a clear day/ slightly cloudy.

Hardly useful from economical point of view...

 

[plopperz]

DealExtreme has a nice selection.

 

[ledow]

It just annoys me as a mathematician... you don't need to be a genius to do the mathematics but nobody bothers. It also annoys me as an amateur scientist - solar and wind are *STILL* a humungous waste of time on anything other than stupidly large scales where they *JUST* make energy "profit" for an enormous amount of effort.

Yes, the *highly* efficient, top-of-the-range solar panels in good-sunshine spots can do lots of great things - power satellites (virtually 100%, but without any atmosphere in the way), power towns (with huge fields full of them and the associated maintenance costs) or power your house (if you can afford the £100,000 up-front cost and are prepared to take the chance that you'll not need to do many repairs over their operational lifetime).

However, 99% of suggested uses and places that sell such things don't realise that all they are doing is making the situation worse by producing some *horrible* chemicals, slapping them into a solar cell, selling them to joe-public, who thinks they are saving money when in fact over their operational life, they could have bought the equivalent in AA batteries or pulled off the grid and not incurred anywhere near 50% of the cost, unreliablity or production emissions (not to mention landfill).

The best example I've ever seen was in my local B&Q (DIY hardware store). A "fit-it-yourself-to-save-money" 2KW wind turbine that was bigger than my car. Aside from planning permission, fitting, connecting to your electrical setup, batteries, ongoing repair costs (ten-foot-wide blades don't take kindly to high winds or just general wear and tear), etc. the damn thing would never (not even at "theoretical maximum", assuming fixed/rising grid energy prices, etc.) recoup the initial outlay of just the device itself within its theoretical operational lifetime (five years, I think it said) if it operated 24 hours a day.

Solar - great for your calculator, but make sure you have a battery in it as well. My calculator has had a solar panel in it since the early 80's, we haven't progressed much since then. Give it another 5-10 years and either it'll work as advertised or it'll be replaced by something that does.

 

[christo930]

I did a search here on the forum but found not much usefull information.

Most links where to a old soldius device or thing like this.

Who looked to me something that might be barely usefull...

I'm not talking about stuff like this thingy

or this thingy.

Seen above linked stuff only put out a measery 80mA ( and that's "max") or so it will take day's, if not a week to charge a 4000mA battery device... Hence that thing not very useful. The build in 1000mA or so battery is also not really "hot" imho.

But a panel with a bit more "juice" (and maybe without a build in battery) may be nice...
So has anyone come across a nice solar panel with some decent output (like 300/400 mA max @ 5V regulated ) ?

edit: adde some pics



Pep boys sells a 17 watt trickle charger for 69.99. That would probably be able to charge most small electronics like a phone or pandora in a reasonable amount of time (less than a day).
You can also use mirrors to maximize the amount of solar rays on the panel at once, but you have to be careful about melting the panel (It has to be a glass, high quality panel). The one at Pep boys looks to me to be pretty good quality.
If you are industrious, you could get individual cells (ebay usually has them) and make your own panel and set it up for 12v and use a car charger. But like others have said, solar is an expensive proposition.

Solar is great in Ca., USA because
1)The teared rates that raise costs as you use more and more electricity
2)Tax breaks
3) The CA sun
But in markets outside CA, it's not really catching on because of all the problems.

 

[Vimacs]

http://events.ccc.de/congress/2008/Fahrpla...ts/2904.en.html
this may be interesting for you

 

[VRAndy]

It just annoys me as a mathematician... you don't need to be a genius to do the mathematics but nobody bothers. It also annoys me as an amateur scientist - solar and wind are *STILL* a humungous waste of time on anything other than stupidly large scales[...]

Granted, but understand that there are situations where Solar is more convenient than line current or batteries.
(Obvious Non-pandora examples : Those monitor stations the gas company puts up. Solar walk-way lights. The Space Station. Etc.)

Pandora examples are harder, but I assume being outdoors all day figures into them. (Or being prepared for some sort of end of the world Omega Man scenario.)

If you planed on being out in the sun a lot, I can see how a one-time purchase might be desirable over a bunch of batteries. Even if the one-time is more expensive, less green, etc.

(We're talking about a piece of consumer electronics that's primarily a toy. If we wanted to be 'green', we could do far more good by simply not buying it and reading a book from the library instead.)

 

[mali]

As I said once in an other thread, take a solar charger with built-in(preferably with replaceable standard cells, you could swap to use them for other devices) batteries, to make recharging in sunlight and Pandora charging timely and locally independent. It should preferably be a trickle charger that generates high voltage spikes to be most efficient in low light conditions.

off topic
What ledow said is sad but true. Small scale photovoltaics do cost more and produce more waste, than they have a benefit calculated over their life time. Solar collectors are mostly ok for sanitary water in summer, if your roof is suited. A combined heat and power unit is the most efficient small scale technology today, fuel cells are the power of the future.
(Edit: With small scale I mean something to power/heat your home, not Pandora or other things.)
/off topic

 

[jakewastaken]

I have a red cross branded Eton S500 shortwave / emegency / weather radio with hand crank and solar charging panel. It has the added ability to charge devices over usb,although it would probably take all day to get to a usable point, and multiple days to get full.

 

[Polossatik]

ok, it may not be economical but the idea to have a solar charger appeals to me.

Most "solar chargers" you can buy do use a battery to "flatten out" the power, I don't really understand why you can't bypass that seen the damn things you're trying to charge already have a charging circuit/battery.
It seams plain silly to do.

Charging a battery seams to have about 75% efficiency (or worse) when charging, aka to fully charge an 7.5 watt battery you need at least 10watt "input".
So if you first charge a battery to use that later to charge a other device then you lose already at least 75% in the "inbetween" battery, then pumping energy into something like a pandora looses another 25% at least... not counting losses in voltage convertors etc.

Assuming your solar panels pump out 10watt, you charge the "inbetween" battery with that 10w then 7.5watt is left in that "inbetween" battery, then using that "inbetween" battery to charge a device you are getting max 5,625 watt useful power in the battery pack of the device.

The "inbetween" battery approach is nice to have some source ready for charging during the night or so, but you should be able to get around as charging the device directly is far more efficient...
Or to charge straight away a pattery pack like a second Pandora battery (but that then needs a decent charging circuit) while you are humping around with the pandora.

I found 9v 250mA 2.1W Monocrystalline panels (12cm x 16cm / 120 gram each) on ebay for about 20 euro each. (Amorphous solar panels are cheaper but seams to be totally useless outside direct sunlight).

If you put 4 of those in parallel (should be possible to make a folding up textile case) you should be able to get a total around 400mA at 7-8 volt even in cloudy daylight. Just on the edge of being useful...

A bigger one like 12v 15w panel (285mm x 420 x 18mm 2.1 kg) for 100 euro is more cost effective but to heavy and a lot bigger.

Seen the 4 solar panels max out on theoretically 1 amp (aka they never going to pump that out ) no problem to pump this into the 5v charger socket of the pandora. Not sure how the pandora behaves when feeded less then the 2 A@5v in the power socket, so I'm going to ask MWeston about this.

Now see if I find a decent DC-DC converter with > 90% efficiency rate... hum.

Seen a lot of stuff runs on 5v it may also useful for the nintendo DS, my N800 etc.
It look like with Nokia you have to careful and limit the power to max 900 mA.
With USB you best limit it to 500mA.. so if I want to use it for USB charging devices I need to use a current limiter in case the solar panels comes in bright shiny sunlight..

edit: speeeling

 

[mali]

Using another battery in between has different advantages. You can use a pulse charger that generates voltage spikes that feed the battery even in low light conditions. The built in charger circuit in Pandora might just ignore those spikes or even get damaged in worst case if you feed it directly without Battery in between. If you don't generate spikes, the solar cells don't charge in low light conditions or if you use more cells to get a higher voltage, you have to put another regulator in between, that just dissipates additional juice in high lighting conditions as heat. Another benefit of an additional battery is the independence of light. You can charge the battery when there is light and charge Pandora even at night. Solar energy is just hard to control in a convenient way, that's all. It's much easier to sacrifice some efficiency but gaining a lot of convenience.

 

[Polossatik]

yeah, the reason why i'm looking at DC-DC converters and not "good old stuff" like a 7805 to level the voltage, that would simply soup up the voltage drop * current as heat... not useful.

I've come across some nifty DC-DC converters who have a a quite serious efficiency and can make nice 5volt out of any > 3volt sources. the only problem there seams the power rating, lot's of stuff for under 200 mA but not much for let's say 1 to 2 amp...
Just not done any serious electronics the last 15 years, so a lot to catch up

 

[mali]

You could build a pulse generator yourself with a transistor and transformer, there are instructions on the web. Just buy a cheap AA solar charger with included battery holder, that has got some additional space somewhere in the case to mount the pulse generator. Often a low-tech design is much more reliable than something overly complex The device you want to build will be much larger, more expensive and less convenient.

Edit:
Here is a nice site with an example and an explanation how it works:
http://www.talkingelectronics.com/projects...larCharger.html

off topic
Edit:
I've once built a similar circuit and put it in a Mini Maglite to drive a white LED with a single "dead" battery. It's a great emergency light
http://bigclive.com/joule.htm
/off topic

 

[Polossatik]

You could build a pulse generator yourself with a transistor and transformer, there are instructions on the web. Just buy a cheap AA solar charger with included battery holder, that has got some additional space somewhere in the case to mount the pulse generator. Often a low-tech design is much more reliable than something overly complex The device you want to build will be much larger, more expensive and less convenient.

Edit:
Here is a nice site with an example and an explanation how it works:
http://www.talkingelectronics.com/projects...larCharger.html



thankx mali, only had a quick glance but it looks this is rather basic stuff you can use for Lead battery's (not really sure it's such a good idea for NiCad ). and certainly not useful for an Polymer Lithium Ion battery like used in the pandora. But a DC-DC converter works quite similar actually, it's a capacity pump.
I have no intention to carry around a car battery

The idea I have now is to explore:

* 9 to 12 volt (1 A max) solar panels who are using the best possible way (DC-DC converter is what i'm now looking at) to output 5V - this should be fairly compact from electronics but indeed maybe a bit more expensive.

* Feed that 5v (1 A max) to the pandora (unless MWeston say's it's not good idea to feed the pandora a unregulated power/amp source) directly

* see if it would be possible to make a not to expensive 5v chargercircuit for an extra Pandora battery - which then should also be possible to use on a USB port or so and not only on the output of above stuff.

This way the solar can be used as a trickle charger for a extra pandora battery (= no extra conversion needed) or as an direct source for the pandora, whatever you fancy. And as a bonus you have a USB charger for a extra battery ...

And seen I'm in the need of a new charger system as whole for all my battery's... hum... let's dig into elector archives...

Of course, if anyone else has a better idea, please feel free.

Edit: your Joule thief is wonderfull !

 

[mali]

I see, that you've settled on a design, I just wanted to give an alternative The circuit I linked to is just an example. I posted it, because there is a nice explanation how it works. I've build a solar charge myself for NiCd some years ago, it worked very well I like the "hidden beauty" in those nifty basic designs :lol:

 

[Polossatik]

totally of topic....

Mali, excuse me for saying but you're completely out of your mind...
bonsai led tree

"128 tiny PCB's with 2816 hand drilled 1mm holes stuffed with 1152 LED's and 256 resistors, then wired with about 200m of solid core cable twisted painstakingly together then powered from a beefy 4A DC power supply."

Wonderful and terrifying at the same time...
You're not related to any of the Monty Pythons, do you?

 

[mali]

:lol:
On a more philosophical note, you can drive to the baker's corner shop with you SUV or you may instead go by foot Read the explanation of how the circuit works, it's worth it