You live in the Third-World? Where to Purchase.
This section is for the "time-challenged" workers among us, who are typically supporting others in a third-world context. These are the ones who say: "I don't care about the details... just tell me what to purchase and where to purchase." Obviously the recommendation we give here, will not be the only option and lots of excellent stores can be found on-line via Amazon.com and eBay.com. But the problem, invariably is how to ship the parts and complete solar systems to where you are on the planet.
Primary Recommendation: GTIS Powermon store: Home Page
Specifically for Solar Panels: GTIS Solar Panels
This can be your "one stop" shop, since they sell parts and complete kits specially designed to support computer systems in the field. The Purchasing and Shipping department is a certified DHL world-wide shipping agent, and therefore if DHL is available in your country, they can ship to you, directly by air freight. If you want to do surface transport (slower and less expensive) that is an option too. You simply have to declare "how" you want your parts shipped and by what method. So the major advantage here is that GTIS Powermon store is highly experienced in shipping parts anywhere in the world.
The least expensive solar panels, by watt are the Solartec line as seen here: GTIS PowerMon Store
These aluminum frame 15 watt panels are a steal at US$18 (SIL Discount) and are of a granularity that is perfect for various applications. You want to power a tablet? Fine, start with one Solartec 15 watt panel. You want to power all day and 4 hours into the night, a modern year 2016 Notebook? Fine, start with 2x the Solartec 15 watt panel. You want to power an old style notebook, say a 9 watt Lenovo x140e model? Fine, work with 3x Solartec 15 watt panels. You have a very old (2014) Dell 6420 model to power running at maybe 12 watts? Fine, you purchase 4x Solartec 15 watt panels (60 watts total). You won't do better, pricewise anywhere else, but you can substitute more flexible options that are handy (see next section) but are more expensive per watt.
The very handy, portable, lightweight, but more expensive Bioenno Panel is perfect for ease of transport, say in a major hiking situation and you are powering a 2016 "Bay Trail" notebook (see Notebook section).
This is built upon the latest thin-film technolgies and folds up nicely. You could purchase two of these for the near 60 watt scenario above. See: GTIS PowerMon Store
Note that in this picture is the handy, extremely light-weight, "Half-Pint" battery bank with controller, but please see the appropriate section for more details on that very useful LFP battey pack.
Different Solar Technologies
The maximum energy we could ever expect from average solar radiation to the ground (or insolation) would be around 1,000 Watts/m2 on the earth's surface perpendicular to the Sun's rays at sea level on a clear day. But of course that would be in the ideal since there are many other factors involved where one is located. Insolation from the words "incident solar radiation" is often expressed regionally on maps as kilowatt-hours per square meter per day (kW·h/(m2·day)).1 Look for insolation maps for your region which can be quite helpful for planning purposes. Obviously this has a bearing on photovoltaic (PV) or “solar” panels, but solar panels are never 100% efficient.
Monocrystalline technology. The highest efficiency ratings have been achieved on monocrystalline silicon cells (c-Si) which are normally expensive to produce since one must grow silicon crystals in cylindrical “boules” and sliced into thin wafers. Hence such panels made from such cells often have an array of circular cells mounted on a substrate. The highest recordedcommercial efficiency appears to be around 23%. Note that due to the extreme competition from the more modern technology, somehow, manufacturing costs continue to fall, and c-SI panels stay quite competitive in the marketplace, even in the year 2016.
Thin Film technologies can sometimes reach 18% and “multiple junctions” higher than that. Most of the commercial production of thin film solar is based upon another compound, CdTe with an efficiency of 11%. These are of interest today because of greatly reduced manufacturing costs, and you notice their rectangular nature when placed on a substrate of some kind, or perhaps mounted on a flexible roll. But "thin-film" can also be mounted under glass and placed on a substrate surround by a heavy aluminum frame, using the same manufacturing techniques for monocrystalline. The difference is easily spotted by the pattern of the cells presented to the sun. Because of the sealed glass and rigid aluminum frames, these panels can be as heavy as 12 kg or more.
The selected materials of thin film are all strong light absorbers and only need to be about 1 micron thick, so materials costs are significantly reduced. The most common materials are amorphous silicon (a-Si, still silicon, but in a different form), or the polycrystalline materials: cadmium telluride (CdTe) and copper indium (gallium) diselenide (CIS or CIGS).
Each of these three is amenable to large area deposition (on to substrates of about 1 meter dimensions) and hence high volume manufacturing. The thin film semiconductor layers are deposited on to either coated glass or stainless steel sheet.”2
Thin Film Flexible Technology
Originally (2010) we saw examples of thin-film technology by the One Laptop Per Child group (OLPC) and their flexible, lightweight 10 watt panels were produced by Gold Peak (GP) solar. They were sold to a captive audience and therefore the GP technology was not generally available for purchase. However, they produced these by the thousands and distributed all around the third-world.
However, today in 2016 there are other suppliers of flexible thin-film panels and available for easy shipment around the world. Consider the SunPower 100 watt: GTIS PowerMon Store flexible panel (SIL members: 20% discount). A 100 watt panel is more than sufficient for certain late model laptops (2014 and older) that were sold by Dell, Lenovo and Asus at the time.
In the past, we have managed to get a few custom GP 20 watt solar panels made for us, and shipped to Papua New Guinea for solar experiments. They proved to be great "low light" performers, yielding great results in overcast or early mornings. However, after years of service, sometimes a noticable sunlight etching or frosting occurred on the surface of these, that was easily restored to transparancy by a thin layer of spray-on clear laquer paint. We cannot say today what will happen to the newer SunPower technology shown at the left. It might do better.
Wondrously light weight (1.8 kgs), these 100 watt panels are very easy to ship by small aircraft. They have grommet holes suitable for permanent mounts, but some users are considering raising and lowering these during the day via ropes to increase security from theft in the village context by night.
As we will see later, the SunPower panels come at the "perfect" size of 30 watts as well, and are therefore smaller, lighter and less expensive. A perfect size for the new 2016 notebooks (5 watts or less) to power all day and in the rainy weather weeks. (See the "Notebooks" section.) The Powermon store sells these 30 watt panels as well: GTIS PowerMon Store
Note: Most modern panels want a standard MC4 connector type on the cable ends for easy modular attachment and interchangeable parts. MC4 parallel connectors are easily available for combining panels in parallel for more power. The older style MC3 connector is fine, but going away in most designs.
CIGS Solar Panels
We have been experimenting with the Global Solar 30 watt panel model GSE-30 shown here.3 The MPP (Maximum Power Point) appears to be 1.7 A at 17.5 volts, and the unit weighs 11 lbs. Dimensions 25 x 25 x 1.3 inches
This panel is relatively heavy, but ruggedly built and the active elements appear to be mounted behind glass, and within a solid aluminum frame. Designed specifically for “off grid” use, these panels are designed for high reliability in very rural applications. Just what we would want. The relative costs is always excellent, but the monocrystalline manufacturers always seem to meet the competion and also lower their prices accordingly. In short, purchase whatever is the proper size for your solar system in watts, and that you can ship affordabilty to your location. Look for suppliers with good long warranties behind their products, which means that at least at the time of manufacture, the company was planning to support their design for a long time. Don't expect to actually "cash in" on the warranty over 25 years. Many solar companies in business two years ago, are now defunct. Competition in this market is fierce.
We have found these CIGS panels to be excellent “low light” performers as well. For a given wattage, you may find that an old-style monocrystalline panel is actually smaller in size and weight.