Notepower Brings the Sun to Your Lap
by Warren McLaren, Sydney on 07.24.05
TH has now showcased more solar backpacks that you can poke a proton at, but many folk are still seeking something that will charge their laptops. In case you missed it, we did make note of the 13 watt SolarMAX portable panel that could manage such a feat. But digging back through our pile of tipster emails has unearthed yet another. Rachel suggested we have a look at the offering from Sierra Solar Systems. So enthused is she, that she even posted a comment on TH too. Anyhow, their ‘Notepower’ units come with either 2 or 3 photovoltaic (PV) 10 watt panels, which they advise is sufficient to juice up most Macintosh or PC laptops, as well as other 12 volt DC devices too. It seems they have been considerate enough to supply a 10’ (3m) extension cord, so your lap and the thing sitting on it don’t also need to be in the sun. We’re not informed how long a full charge might take but we do know that the 20 watt unit weighs 3 lb (1.4kg) and sells for $250 USD. Thanks Rachel. ::Sierra Solar Systems
You know, I kind of hate to be a continual party-pooper about this stuff...but I will. :-)
You cannot run a 65-watt laptop off of a 30-watt solar panel--laws of physics and all that. Sierra's (and other company's) "run and/or charge" spiel is just flat-out misleading. There are very few laptops that will run off of 30 watts these days; most require at least 60W and some as much as 90W (or more). The only laptops I know of that will actually run off of a single 30W panel are some older Apple Powerbooks.
You can, however, easily charge the battery on a 65W laptop using a single panel and the laptop's DC car power adapter, and it's probably a good idea to use a DC-DC converter to provide the machine with a steady 13.8 volts of juice.
My 32.2W solar panel charges the 14.8V, 2400 mAH battery in my Inspiron 700m in about six hours in full sun. In order to actually run the laptop, though, I need two 32.2 watt panels.
To find out what a laptop will require to run off of solar, look at the AC power supply. It should either have the watts listed, or you can get the watts by multiplying the output voltage by the output amps. Thats the panel output you need to run your 'puter from the sun.
You might get away with 20% less or so, depending on the laptop. But folding charging panels tend to come in 10W, 20W, and 30W flavors, so you'll probably still need two panels.
I use a Connecticut Solar 32.2W folding panel for charging my laptop. It weighs four pounds, folds down to 15"x17", and costs $269.95. It's swell.
"You cannot run a 65-watt laptop off of a 30-watt solar"
This the reason I am sort of keen on the battery units. Somehting like the Solio (iPod panel) for laptops would be nice, if only the battery were in small form.
My iBook is 45-watt, so if I understand correctly a 30-wattsolar panel unit may not be able to power the laptop fully, but it will slow down the batery discharge (because it is charging the battery while it is being used). Correct?
thanks!
That's exactly right. The amount of "extra" battery life you get will vary depending on how much more power you're using than the panel is able to put into the battery, and I'm not at all sure what the math would be on that.
There's alot of variation in the minimum power that different laptops will run on, but 30W is more than 30% below the 45W watt rating, so you're probably out of luck. That said, it's all sort of experimental...you may get a 30-watt panel and find that your iBook runs fine, or that it conks out if you try to burn a CD or some other power-consuming task.
Speaking of the Solio--there are equivalents for laptop power (CT Solar makes some). You use the solar panel to charge a sealed lead-acid battery via a charge controller, and then run the laptop off the battery. SLA batteries are heavy, though--the 8AH battery weighs five pounds (an 8 amp-hour battery would run a 65W laptop for roughly eight hours).
What we need are true low-power laptops...30 watts or below. I looked around for a small, modern low-wattage laptop for this application, and it seemed that the smaller they were, the more power they used!
This is an interesting site - I have been looking for a solar power charger for my PowerBook for some time but have found very little info anywhere on the net.
I agree - a 30 w panel isn't much good with today's laptops and carrying around 2 of these 3lb cases and a 4lb laptop wouldn't leave much room for anything else in your rucksack.
I have been told that Iowa Thin Film Technologies (http://www.iowathinfilm.com/) produce a military 60 w folding panel - the word 'military' kind of says it all really and suffice to say I haven't found an outlet for it anywhere (yet!). ITFT have some info on the folding panels - but nothing specific on the 60 w (http://www.iowathinfilm.com/products/solarbattery/).
I'll continue to search the net for an outlet - failing that I will email Iowa.
Hi, I ran an old 486 laptop staight off my power unit comprising 2 x 100 amp hour batteries fed by 25Watt and 32 W solar panels. The panels put out their power (varies with sunlight) at about 18 volts. Power demand by modern laptops is much higher, but you can keeep the lapop hooked into a car battery to keep the battery charging whne not in use. Details in 'Grass Roots' magazine 2000 (forget which issues). Highly portable solar panels would be too small for serious laptop use. Aarn