Portable Solar Power For Portable Hardware?

Tjeerd writes "Because the 'green revolution' is accelerating, I felt it was time to get involved. Last week I started with buying a portable solar energy charger for my mobile phone. But soon I was thinking of also recharging my Asus Eee netbook with a portable solar energy recharger. I found things like the Portable Power Pack, Foldable Solar Chargers, and the Solar Gorilla. The Solar Gorilla looks quite interesting and might be able to recharge my netbook and fits nicely in a rucksack. But I would like some real-life feedback. If you have experience with these or other portable solar devices, what has worked for you?"

Comments

Come again. Because what?

[Anonymous Coward]

"Because the 'green revolution' is accelerating, I felt it was time to get involved."

Have another sip of cool-aid. Everybody is doing it.

Not saying that being more green is bad - just your reasons to do it.

And I'll quote the famous wise guy Kermit.

It isn't easy being green.

Plants

[Smivs]

I have been using solar energy to 'recharge' my houseplants for years.

Re:Plants

[theaveng]

And if you use ethanol in your car, you are using solar power. But as for solar cells for your laptop? It creates MORE pollution, from the manufacturing process of creating the cells, then simply using a few pennies from your local coal electric plant. You make the air pollution worse, not better.

The only time solar cells will reduce pollution is if you use them for mega-kilowatt devices, like heating units or air conditioners for your whole house. Only then do you overcome the pollution contribution from manufacturing the solar device.

Solar and handcranked are the way to go

[BadAnalogyGuy]

Solar has a lot going for it as an alternative power supply for portable items. The problem is that many of those items aren't exposed to sunlight for enough time to actually charge the reserves.

That's why I use a hand-crank as my primary source of alternative power to my portable items. Especially in the winter time when sunlight is at a minimum, good old elbow grease is always there.

Re:Solar and handcranked are the way to go

[Sarten-X]

Until you're out hiking somewhere, and you lose the use of your arms in a terrible accident involving a pine tree, a squirrel, and a toothpick. Of course, your boots are still tied on, so using feet to crank isn't an option either.

Where is your precious elbow grease now, huh?

Wait a second... this is slashdot... "hiking" consists of going to the door to sign for the latest shipment of your chosen caffeine source...

Re:Solar and handcranked are the way to go

[rusl]

Are you serious about hand cranks?

I'm a cyclist and I sure would be. Human power is seriously overlooked. Using your much stronger leg would be easier.

I have a cheap hand crank flashlight that has a plugin supposedly able to charge a cell phone. Never tried it but I don't see why it wouldn't have sufficient power - a cell phone is extremely frugal and has a great battery. The biggest obstacle would be getting the power at the right level to charge and circumventing proprietary plugs for phones.

Are there practical crank chargers out there?

Thus the sun charges the plant, I eat the plant, I crank the laptop. (Or you could insert meat into that supply chain if you wanted it less efficient but more tasty)

Re:Solar and handcranked are the way to go

[sumdumass]

Hey, wait a minute. I found myself in that exact same situation last year. Did you read my article in "outdoor geek's playhouse"?

Well, if you did, you would have realized that the answer was using the candy wrappers to fashion a sail on the cranks with your tongue then role over and fart while moving your ass from side to side to turn the crank. It helps if you ate microwave burritos before the hike. You then think about using the force when you use your tongue to dial 911 and wait for the ranger to show up talking about putting on his robe and wizard hat.

Re:Solar and handcranked are the way to go

[nospam007]

"Are there practical crank chargers out there? "

Tons!

http://www.nextag.com/crank-charger/search-html

Re:Solar and handcranked are the way to go

[MaxwellEdison]

I hear there's a sale on over at the Punctuation Hut. May want to pick yourself up a few periods, or at least some commas. Honestly, your post is the equivalent of bungee jumping. I think I have your meaning and then the next sentence comes barrelling in and yanks it away from me.

Enviromental cost of making the device?

[Bwian_of_Nazareth]

I looked at the solargorilla but could not find any information about how much energy I need to generate with this device to reach the green break even - to offset the environmental cost of making this device. Anyone knows this information?

Re:Enviromental cost of making the device?

[TheLink]

You can often have a good idea from the price tag if it's close enough to the cost of making it.

While it's not exact, it shouldn't be that far off in those cases.

If a device is priced at USD1000, costs USD500 to make, lasts 10 years and only saves you USD20 a year, it's probably not worth it in terms of the environment.

While it's true that in some places they don't value their environment that much, it's still not zero - even in China they are starting to value it more, and so it will be added to the cost of making stuff there.

Better off with a long extension cable

[Anonymous Coward]

These panels are ridiculously expensive, and produce a pitiful trickle of energy. Save your money and get a long extension cable -- or, if you absolutely need the portability, just get some extra batteries and lug them around with you.

Solar is a great idea, but it's one whose time is not yet come.

Watch out

[Bruce Perens]

There are a lot of underpowered units with inferior solar cells out there, for sale at very large markups. You probably want a folding unit, with reasonably durable cells. The ones I've seen aren't so great. There was a 6-watt folding unit at Fry's for about $100. That's 6 watts in full sun in optimal conditions, not nearly enough to operate and charge your laptop at the same time.

If you are running linux, the stuff in /proc/acpi/battery/*/* will probably give you the battery voltage in Volts and current draw in Amperes, and you multiply them together to get Watts. You need about twice that to operate and charge at the same time. Charging might be 60% efficient.

Re:Watch out

[dgatwood]

Not nearly twice the consumption to charge. My MacBook has a 60W supply. With a MacBook Pro, that's just enough to run it without charging; the battery won't charge, but it doesn't drain the battery, either. With the MBP's 85 Watt supply, it can do both. The EEE PC draws 24W or so at full tilt, 36W to charge. For an optimal charge rate, yeah, doubling the maximum draw is a good idea, but most laptop manufacturers base their power supply choices on 25-50% over the maximum drain, not double.

On the flip side, this means that even with an ultra-low-power netbook, you're still talking about 4-6 of those panels before you start charging at all during normal use even in full sun. Solar panels on your roof: good idea. Solar panels on your laptop: waste of money, time, and materials.

How many watts does it produce?

[Joce640k]

I couldn't see a wattage anywhere and that makes me very wary.

If you have to leave it a whole day to get ten minutes of power then it's not much use (and expensive!)

Re:How many watts does it produce?

[TheLink]

One link said 30W for 490 UKP. Another had a 60W product for 600UKP. So I shall use this.

Assuming domestic electricity in the UK is about 16p/kwh ( http://www.britishgas.co.uk/pdf/Elec%20Price%20guarantee%202008.pdf )

600UKP = 3750kwh worth of electricity.

Assuming very generously you get that 60w for 8 hours of sunlight (laugh if you're using it in the British Isles), this means 480wH a day = 0.480kwH a day.

3750/0.48 = 7800 days = 21 years for that panel to make 600UKP of electricity.

It does not appear to me to be a "Green" _alternative_ to mains power.

BUT if you were intending to be temporarily in the middle of nowhere, that 600UKP for 60W weighing 2.6 pounds may start to look like a bargain. It will cost a lot more in time, resources, and environmental damage to pull power cables to your ever changing remote location.

So is it a good option for _portable_ power?

I don't know - it might still be worth considering other sources of power dynamo, generators, etc.

2.6 pounds = 1.2kg. 1.2kg of vegetable oil contains 31MJ or 8.6kwH. It takes 143 hours of 60w to produce 8.6kwH - that's 18 days of 8 hour sunlight.

Yes there are inefficiencies in converting cooking oil to electricity, or diesel to electricty.

So do more thorough estimations/calculations to see which makes more sense for your scenarios.

If you're only spending a short time from mains power, it probably makes more sense to carry enough rechargeable batteries to last the whole time.

solarcells in the netboot/laptop lid

[Ptur]

I'm still waiting for the first netbook or laptop to feature solar cells in the lid, instead of the stupid logo they put there now.

Come on, it can't be that hard? And don't tell me I'm the first to think of this?

Re:solarcells in the netboot/laptop lid

[Sod75]

So you want to leave your laptop out in the searing sun for hours straight, just to charge the battery for a tiny amount (not a lot of solar panel space) ?

Other locations.

[Gnea]

Frys.com has some affordable solutions. Pricewatch seems to have a scant selection, although very unique.

"Green Revolution"

[lobiusmoop]

While the sentiment is admirable, please don't use 'going green' as an excuse to buy more toys; just buy the toys. Realistically, the power ranges you are talking about are in the 50-100W range for portable solar charging. In comparison, a typical 100 horsepower car is using around 75KW. (1HP=750W), so the power savings possible by simply traveling less dwarf anything possible via solar.

If you are _really_ concerned about going green, the biggest (and likely simplest) impact you can have is to never have children, especially in the developed world where per-capita energy consumption is highest.

Solar Power carbon-hostile?

[lkcl]

Before saying "I have found a way to save the planet!" check that the cost in planetary terms of the product is worth it:

http://www.genersys-solar.com/carbon-savings/carbon_footprint_solar-panel_manufacture.asp

seems to be saying that there's a reduction of the carbon cost when compared to other power-generation mechanisms, over the expected 35 year lifespan of the home-sized solar panels.

are the small, portable solar panels you're advocating as carbon-friendly?

Re:Solar Power carbon-hostile?

[dgatwood]

Where did you hear that nonsense? The typical solar panel lifespan is measured in decades. The energy produced does decrease over time, but a ten year lifespan is absurdly short for modern panels. Many home solar panels have a guarantee on their output power for a period of 25 years.... If they only lasted ten, those manufacturers would be replacing a whole lot of panels....

I think you're thinking of the break-even point. Typically you break even cost-wise compared with grid power at about the ten year mark.

Green Gadget Challenge

[MattSparkes]

I wrote a feature recently where I explored if it was possible to run all of the standard office gadgets from sustainable power - it includes quite a few product reviews.

Wait for Better Solar Panels

[EEthan]

In my experiences dealing with photovoltaic power supply systems of all sizes, I've become convinced that solar panels are currently not a viable solution for powering mobile devices for a few reasons, mainly cost, unreliability, and inefficiency.

First of all, look at how much these things cost. the Portable Power Pack retails online for 420 pounds, or about $660. You could buy more than a dozen eeepc batteries for that much and just keep them stocked in your car or rucksack or whatever. LiIon batteries aren't terrible for the environment, and you won't even need sun to use them...

Speaking of the sun, I live in beautiful southern California, where one can definitely count on the sun 99% of the time. But most parts of the world aren't that sunny, and even if the sun is shining there's bound to be a tree/building/civilization in the way just when you need it most. You're not going to walk or drive around the city looking for a nice open space to sit in for an hour and roast while you check your email, just so you could feel good about spending $600 on a solar panel, no matter how good your intentions are.

so how do you charge your devices with a solar panel while actually "on the go"? you can try to drape it over that rucksack of yours while you're walking somewhere, but if the panel isn't facing the sun directly you won't get anywhere near the peak power output advertised. Instead, you need to find an open space and lay out your few-square-foot mat-- and then you're tied to the ground.

And what about that generous peak power they keep advertising? solar panels output their peak power when they are laid out flat, directly facing the sun, on a completely clear, sunny day. I know from personal experience with small panels that small deviations from the sun-facing angle mean big drops in power.

So alright, let's say that you bought a 30 watt panel and it's noon on a clear, sunny day, so you're getting 30 watts out of it. Please correct me if I am wrong, but I believe that EeePCs use 36 watt power adapters. How do you plan on charging and using your EeePC on less than 36 watts WHILE charging your phone and whatever else you have plugged in? all you could possibly do is increase your battery life considerably-- which might be great, but i'm not sure it justifies the costs and the effort involved.

Here's my suggestion: Save the money you were going to spend on that portable panel. Use a little to buy extra batteries for your gadgets, and put the rest in a savings account. Save up for a large, multi-kilowatt solar system for your house, which will save a lot more greenhouse gas emissions per dollar you spend than one of these portable things. Use that home solar system to charge your batteries, and you're gold... er, green.

Back of the envelope...

[Dice]

The power brick for my laptop claims that it draws 65 Watts. The average incident solar power per square meter on Earth is 1000 Watts. If we assume a solar cell with 30% efficiency I would need 65/300 = 0.216 square meters of solar cell for my laptop. That's a square 46.5cm on a side, or around 18.3 inches on a side.

Not too bad, but not something I would carry with me unless I was severely limited in terms of power sources.

Some real life feedback

[dirkjan]

I had a Solio Classic to charge GPS logger and phone while hiking for multiple days. It worked okay, good in very sunny conditions (in northern europe) and not enough to keep up on clouded days. But it was stolen and now I have a Solar Mio 31 which works better, even in clouded conditions. It manages to keep the batteries of a mobile phone and GPS logger charged in average dutch weather, back pack mounted or behind a south facing window. As I also use it at home, I haven't touched the normal chargers in a year...

As for price or "greeness", they won't repay themselves financially or impactwise. But I see part of it as gaining experience with solar cells and it is nice to see your week long treks through nowhere in google earth...

This isn't "green"

[Joce640k]

The CO2 produced by making those things is more than you'll ever get back from using them.

Make one car journey less (eg. the one needed to go and buy the solar charger) and you'll probably achieve more green credit.

Re:This isn't "green"

[stranger_to_himself]

The CO2 produced by making those things is more than you'll ever get back from using them.

Make one car journey less (eg. the one needed to go and buy the solar charger) and you'll probably achieve more green credit.

Probably right at the moment - but buying into this technology now will help drive development which hopefully will bring far greater long term benefits.

Re:This isn't "green"

[pla]

The CO2 produced by making those things is more than you'll ever get back from using them.

That myth really needs to die, once and for all.

You've phrased it one layer of indirection more than the standard claim (it takes more energy to make them than they will produce over the useful lifetime), but they reduce to the same concept (since virtually all of the CO2 "produced" during manufacture comes from the energy input).


A trivial economic proof should demonstrate this fact - The payback period for wind or solar runs around 10 years on average (a lot less in ideal climates, somewhat more in suboptimal ones).

The expected lifetime of such devices averages around 20-30 years (most importantly, more than the payback period).

It follows, then, that in order for it to take more energy to produce the device than it will generate over its useful lifetime, the manufacturer would effectively need to spend twice as much on electricity as they sell the finished product for... And that ignores other overhead such as labor and raw materials.

How many companies do you know of that sell at a massive loss and stay in business?

Re:This isn't "green"

[Sebilrazen]

GM, Ford, Chrysler?

Re:This isn't "green"

[Tx]

Rubbish. How many 10year old devices are you using? Even if the real lifespan of the device is actually accurate, the real world lifespan is much shorter. Technology moves on, different devices with different requirements come into vogue etc. For the type of portable devices in TFA, the chances of them being still in use in 10 years is minimal. Moreover, they are in many cases going to be occasional-use (the odd hike or trip) rather than daily use. It's not even worth doing any finger-in-the-air math to refute your claim, it's so obvious. You might possibly have a case for permanent photovoltaic panels on houses/buildings etc.

Re:This isn't "green"

[bigmouth_strikes]

Not rubbish at all. There are plenty of small photovoltaic panels that can power/recharge almost any powered gadget and there is little point in replacing those as often as the gadget. It all comes down to connectors. We have all this beautiful technology and we can't agree on their interfaces.

Re:This isn't "green"

[crashumbc]

We have all this beautiful technology and we can't agree on their interfaces.

The interfaces are intentionally designed not to match... Blame the greedy Manufactures that want to sell a new car charger with every cell phone...

Re:This isn't "green"

[pla]

Rubbish. How many 10year old devices are you using?

Gadget-scale, very few (an ancient Palm, an few graphing calculators, a watch, a GPSr... Not much more).

On the appliance scale, however (which better matches the concept of alternative energy sources)... Fridge, washer, dryer, water heater, furnace, two TVs, my car (almost), stove, microwave, a handful of fans (from ceiling to box)... I could probably come up with a few more.

The things we take for granted around the house, that we just expect to work when we press the button, tend to have real lifespans over ten years.


For the type of portable devices in TFA, the chances of them being still in use in 10 years is minimal.

What does the device itself have to do with anything? TFA talks about powering those devices, the devices themselves don't particularly matter. For an analogous situation, I have rechargeable AA batteries older than some of my current gadgets - Does that make rechargeable AAs not a viable source of portable power?

My Bike Trip and Solar Panel Experiences

[SJrX]

I had done quiet a few bike trips and generally can't be without my iPod, PSP, and cellphone so I have had some experiance using Solar Panels previously, though never for something as power hungry as a notebook/netbook. Two years ago I purchased the Soldius 1 Solar Charger, seen here: http://www.thinkgeek.com/gadgets/travelpower/7d34/. I found that even stationary it really just drained my iPods batteries and made them unusable, as the change in voltages associated with clouds would cause the iPod to constantly redetect that the charging had started and illuminate the screen thus draining more power. I may have only gotten one meaningful charge or two out of it, in the two years I've had it. It also didn't charge some devices, that were USB powered, and seemed very brittle. This summer past, I had taken time off to go cycling for 2 months across Canada, and so invested in another Solar Panel, the SolarFocus SolarMio 31 Solar Charger: http://www.mec.ca/Products/product_detail.jsp?FOLDER%3C%3Efolder_id=2534374302697169&PRODUCT%3C%3Eprd_id=845524442620595. It was very durable, and I had it strapped on my rear rack, even in the worst rains. It also has a portable battery pack so you can charge during the day, and then have power for later, and it charges relatively quickly. I found that 4 hours would give it a full charge to the battery, (it is probably much better than this, as being on my bike rack and in motion means that it is not really positioned for optimum solar energy collection) and that would charge my iPod to 90%. It also has an external AC adapter to charge the battery overnight, and a USB port for 'most' USB devices. Some draw backs are that it didn't charge my Phone at the time, a Motorola KRZR, and after my trip I found out it doesn't charge my iPhone (which is kinda a disappointment). Another plus is that the battery is detachable, and while replacements/spares are expensive, it made it convient to charge at camping sights. They make an equivilant solar panel for laptops which is a bit pricer at CAD $595: http://www.mec.ca/Products/product_detail.jsp?FOLDER%3C%3Efolder_id=2534374302697169&PRODUCT%3C%3Eprd_id=845524442625524. Which is too rich for my blood at the moment, but if the quality is anything like this one, I'd definately recommend it. Finally some other words of wisdom: 1) The Solar Device compatibility list actually seems to matter at least for obvious devices not listed, just because it's USB doesn't mean it will charge it. 2) Getting a dead iPod (I had both a iPod 4G Photo and 5.5G Video) to charge is a bit tricky if you are charging straight from the sun in less than ideal conditions, as when it turns on, the screen comes on maximum brightness, and I believe stops charging for a moment, and will cause the iPod to turn off. I found that both the above would eventually charge by just booting it into Disk Mode a few times, eventually it would have enough power to stay on in Disk Mode and charge. Finally after two minutes rebooting it into Normal mode, so that the screen turns off resulted in a quicker charge.

PowerFilm

[DynaSoar]

The foldable you mention is from PowerFilm. They make many different devices as well as components for building your own. http://www.powerfilmsolar.com/products/portable%20and%20remote/index.html
I went the build-your-own route using their thin-film cells. I needed a power source for a laptop in the field, so I put one together that I could epoxy to the laptop lid. It's still on duty 4 years later. I also needed a source on board the ultimate portable device -- a rocket weighing less than 2kg total and capable of handling a vertical acceleration of 20 G to Mach 1+, supplying constant high grade power to the recording altimeter that also controlled the parachute ejection system. That system has flown over 20 times. I put their stuff through some hellacious stress testing and the only failures I've had were my fault.

Decomas

[Decomas]

Yes! I actually have that EXACT model from the first link. It is 20 Watts and I run all my usb devices off of it simultaneously. I think I got up to about 7 or 8 devices at once before it reached its peek. It's great, I worked at the beach all summer and carried the panel in my bag every day, only taking up the size of a thin composition notebook. and the great thing is, IT FLEXES like a softback book. So there is no need to worry about breaking the "glass" on the panels.

NOMADIC POWER!

I want to get the Y adapter and bump my power up to 60 watts with a 2nd solar panel. I would suggest E.Bay for some great deals on these panels. such as this. http://cgi.ebay.com/35-Watt-Foldable-Solar-Panel_W0QQitemZ190262865303QQcmdZViewItem?hash=item190262865303&_trkparms=72%3A1205|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3911.c0.m14

Re:It wouldn't work

[capnkr]

Maybe I should get my calculator out before continuing?

That might help, but moreso - doing some research into real-world applications will teach you more than anything else...

Solar panels may produce electricity from non-direct light, but it isn't much. With a panel that small, I would be surprised if it would produce even millivolts, without direct lighting. I managed to wear down the 200+aH house battery bank on my boat over the course of 7-10 days primarily just by using the radio, when my relatively large 80W solar panel was set obliquely to the sun. That is the reason many cruising sailors use devices like the James Baldwin's Solar Tracker. You NEED to keep the panel face approx 90* to the suns rays in order to consistently produce usable amounts of electricity.

So many people living 'on the grid' tout solar as the new energy source that will solve all our problems, but when you've lived with it for a few years, you will begin to understand and appreciate some of the inherent limitations. That is the reason that most cruising sailors (people with experience living OFF the grid, completely, for months or even years at a time) use a combination of energy-producing methods instead of just one. Solar and wind (via small windmill-type generators) are the most common methods.

Cows

[Smivs]

I turn cows into cheeseburgers summary cheesburgers are enviromentaly friendly

But not very cow-friendly, you insensitive clod!