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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?"
"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.
I have been using solar energy to 'recharge' my houseplants for years.
Smivs on the intertubes!
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.
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.
Bruce Perens.
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?
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.
"I bless every day that I continue to live, for every day is pure profit."
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?
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.
Matthew Sparkes
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.
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.
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...
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.
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.
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.
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.
"...there are some things that can beat smartness and foresight. Awkwardness and stupidity can." ~ Mark Twain
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?
GM, Ford, Chrysler?
"There are no facts, only interpretations." --Friedrich Nietzsche.
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.
Oh, I can't help quoting you because everything that you said rings true
I turn cows into cheeseburgers summary cheesburgers are enviromentaly friendly
But not very cow-friendly, you insensitive clod!
Smivs on the intertubes!
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...