Under Construction

Battery chargers Rollable/foldable/
Name Watts Price Notes Where to buy
12 v Car Battery
Brunton 9 $230 rollable Amazon
Silicon Solar 12v Battery Charger 15 $120
Sunlinq 12 $155 foldable. 12V Global Solar, electricfence-online.co.uk
You can use car charger adapters with the 12 V units above to charge personal electronics.
Solar Panels solid - (s) sale price
Name Watts Price Notes Where to buy
12 v Car Battery
Thunderbolt Solar 45 $140(s) 3 12.4x36.4 panels. Includes 300W inverter Harbor Freight
GoalZero 30 $180 1 panel 18x21" Costco
Sunforce 60 $270 4 13.5x42.2" panels, Includes 200 W inverter Amazon
Personal Electronics: Portable Solar Power Note: Most of these require full sun (no shade) to work.
Name Watts Price Battery
Incl. *
Notes Where to buy
Brunton Foldable Solar Pannel 5 $59 n foldable, rating 3 (REI)
Brunton Foldable Solar Array 26 $333 n rating=4, 12 V, CIGs Amazon
Goal Zero Nomad 7 panel † 7 $60 Guide 10 below rating=4, c-Si
Charge batteries in 1.5 - 2 hrs.
Goal Zero Nomad 13.5 13.5 $120 Charge Sherpa 50 power pack REI
Goal Zero
Zero Guide 10 battery pack
$60 USB Charge rechargeable AA and AAA. USB in/out. REI
Energizer SP2000 Energi To Go 1500 mAh, 5V $100y wall rating 4.5 Costco
Solio 1 $100 wall folding. with cell phone adapters. EMS
Silicon Solar Chargers $40 ? foldable
Global Solar AA Battery Chargers 2.2 $250 ? foldable Modern Outpost
SunLinq 6.5 $99 ? folding 21st Century Goods
SunLinq 25 $312 ? folding Amazon
* Battery - All accept solar charge some also have - Wall - charge from wall; USB - charge from USB
A chargeable battery is an advantage in a basecamp trip allowing you to leave it out during the day to charge the battery, then charge your portable electronics at night off the battery.

Solio 1 W - One hour of sun will give you enough juice to play your iPod(TM) for about an hour.

Nomad 7 comments by Ernest Mayer:
No other panel has the output of the Nomad 7. Its closest competitor is the Brunton panel. The Brunton weighs 20% more and is rated to output 30% less than the Nomad 7 (Brunton = 5 watts, Nomad 7 = 7 watts). In my testing the lower output was verified. The off-axis performance of the Nomad 7 is superior. It maintains full output to a greater angle of sun than any other panel I have tested.
The Goal 0 batteries that ship with the Guide 10 are the best of their type I have tested. They are low-discharge, like the Eneloops, but much better. The Eneloops are rated at 2000 mAh, but charge only to about 1900 mAh capacity. The Goal 0 are rated at 2000 mAh, but charge to 2200 mAh.
Review of others:
1. Powerfilm USB + AA: This one has a great form factor, is flexible and very durable, and is the lightest weight and most compact of all the solar chargers. Its fatal flaw is that it simply does not put out enough power to be practical in extended backpacking. It does not fully charge the AA batteries when it indicates a full charge, and is not nearly as flexible as the Nomad 7 for connection. The unit was replaced on warranty, but the replacement performed exactly the same. I tested a total of four of these, and all performed the same. Customer service was good, after spending weeks trying to get their attention, and this happened several times.
2. Solio Classic: This one has a nice form factor, but the unit simply does not charge its internal battery nor a connected device at all adequately. Just in case, I had it replaced on warranty and the replacement performed exactly the same.
3. Xpal Power SP-2000: Same as the Solio. Internal battery rated at 2000 mAh, only charges to about 1100-1300. Not enough power overall to be practical. Very good customer service.
4. Brunton Explorer: A good panel, but not enough overall power. Weighs 20% more than the Nomad 7, output is 30% less.

Types: - Cost and Efficiencies
Efficiency depends on the material and purity of the solar wafer.
There are several types:

    Type                               Efficiency             Cost
Crystalline Silicon (first generation) (silicon wafers) (rigid)
 Wafer thicknesses in the neighborhood of 200 to 300 µm. 
  MultiCrystalline (poly-Si or mc-Si):  14-17%
  MonoCrystalline (c-Si):               18-24%                 $2.48 per watt-peak.
Thin Film Technology (second generation) (flexible and rigid) $1.76 per watt-peak
  Thin-film technologies reduce cost by reducing the amount of material required
  at the cost of some efficiency. Thickness of 1 µm or less.
  Amorphous Silicon (a-Si)              10%
  Copper Indium Gallium Sulphide (CIGs) 11-14%.- Most potential
  Cadmium Indium Selenium (CIS)         11.5-14%
  Cadmium Tellurium (Cd-Te)             10-15%
Third generation solar cells - Still in R&D in 2011 
   Multi-layer ("tandem") cells made of amorphous silicon or gallium arsenide,
   plus other technologies to increase efficiencies beyond the
   Shockley-Queisser limit of 31-41%.
Efficiency of Solar Cells made of Silicon(Monocrystalline,Multicrystalline) ,Thin Film (CIGS,CIS,aSi,CdTe,CZTS),Multijunction at Green World Investor
Solar panel - Wikipedia
Solar cell - Wikipedia
Thin Film Solar Cell vs Crystalline Silicon Wafers " renewablesales

  - c-Si - MonoCrystalline Silicon
  - CIGs - Copper Indium Gallium Sulphide
  - EVA - Ethylene Vinyl Acetate - transparent layer between PV cells and which binds the layers of a solar panel together.
  - PCE - power conversion efficiency
  - p-n junction - Junction of p-type and n-type semiconductors. Used in semiconductor electronic devices such as transistors, solar cells, LEDs, integrated circuits, ...
  - PV - PhotoVoltaic

Solar Power Systems
Other web sites:
Silicon Solar
12V Solar Battery Charger Reviews | 12 Volt Solar Panels Blog
Home Panels:
SolarPanels at Wind & Sun
HowStuffWorks "How Thin-film Solar Cells Work"
Compact Portable Solar Power Systems at ModernOutPost.com
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last updated 6 June 2011