I've read about portable solar panels, such as the Anker, that claim to charge laptops. Anyone every try one?
I've got a reasonable amount of experience with solar. First things first: solar does NOT provide a lot of power, unless you have a big panel.
As an example, there are some USB power banks with solar panels on them that actually discharge
the battery while in the sun most of the time, because the charging electronics draw more power than the panel produces, in all but the brightest of sun. Don't bother with anything less than a square foot of cell area.
Second, USB devices are easier to charge because they use low voltage DC power. The optimum arrangement is to get a decent capacity (10,000mAH) battery bank (I prefer Kmashi, <$20 shipped from Amazon) and use a fair size solar panel to charge that. Then use the bank to charge the device. You'd be correct to point out that converting power once instead of twice is more efficient, however it's not often convenient to leave your device by the panel. Fill up the bank whenever the sun's available, and use the bank to refill the device when needed, including when it's dark or you're on the move. (or using your device) Plus, if your panel is putting out 15w and your phone can only draw 10w at a time, you are throwing away 5w of power by charging your phone directly. You want that to top into your bank for use on another recharge later when the sun's not out.
I got a killer deal last year on one of these, I think I paid $60 for it.https://www.amazon.com/StrongVolt-SV-18WFLDBLK-Strong-Solar-Charger/dp/B00XM7OIO2
This is the sort of thing you want at the minimum - 18 watts of tri-folding panels. Anything less than 18w is a waste of time and space. Don't save and get two panel. Make sure the panels are big.
I also bought several SUAOKI 20W Solar on sale a few years ago for about $35 ea. Sold them to friends who where very grateful to have the deal. https://www.ebay.com/itm/292591224226
Both put out about the same power, so the Suaoki are definitely a better deal. They are almost useless when slung on the backpacks as often shown. Lay them out so they are directly facing the sun for best output, angle is very important and 30 degrees off can cost you half your output power. This means they need to be adjusted several times during the day if you've got a lot of charging to do.
Kmashi banks are holding steady on price and are good quality. https://www.amazon.com/KMASHI-10000mAh-Portable-Power-Output/dp/B00JM59JPG
Charging laptops is more difficult because they all have their own custom DC ports, convert down to a wide variety of DC voltages, can be very picky about the power they receive, and usually end up being more convenient to just use their 120VAC adapter pack to charge from. This not only makes conversion less efficient, but adds another step in the process. A substantial panel will be needed to charge the higher capacity battery also.
Here's my suggested "kit" for laptops:
(I own two, they work VERY well and are light and semi flexible, BIG plus for portability)
charge controller: https://www.ebay.com/itm/273205062626
(there are many out there, get one that's "MPPT" and has an LCD display) I've got several controllers and they all work more-or-less equally well.
Then find your car battery of choice. junk yards get $22 or so for a good used car battery. ask for the largest one they have available, there's no difference in price! You can skip the battery and lighten your load, but charging will be spotty at that power level without a battery to buffer the power. At least get a small lawn tractor battery.
I don't have a preference for inverter, but you should get one rated 300w because of how over-stated their ratings are. 150w inverters will likely overheat and run inefficiently at the full 70w draw from a MacBook pack. Here's an example I spotted, though I have no experience with this specific one: (ymmv) https://www.ebay.com/itm/201941981951
- "pure sine wave" look better and are, but you don't need that and it makes the inverter less efficient, at a time when power is a valued resource.
Watch for deals on solar, they do pop up from time to time on Amazon and Woot. (Black Friday is coming up too)