Re: Solar charging
Lower cost back packable solar can be put together with USB stuff... Mine had a 5 watt (advertised) double flex panel (actually less than 2 watt output) connected to a 13,000 ma hr li-ion power pack; the wires needed were more than I wanted to deal with though.
Beware of low cost solar panels they often cannot meet their own specifications; experience shows that. a small (6 x12 inch, physical size) panel will probably not supply 20 watts, (4 amps for 5 volt systems). I have some, much larger than 6"x12", that are rated at 7 to 10 watts (12 volt system) that actually put out 3-4 or thereabouts. a more realistic output for a 6" x12" panel in a 5 volt (USB) system would probably be on the order of a watt or 2 (possibly much) less.
Especially Chinese, but also other manufacturers/marketing departments inflate their numbers and or/use calculation tricks to get impressive specs (a 5 volt panel outputting .5 amp (500 ma) for 8 hours could be said to supply 20 watts per day (the advertising will probably leave off the per day) .5 X 5 X 8 = 20 although actually .5 amps x 5 volts is 2.5 watts. NOTE; 2.5 watt hours per hour into a USB output is ain't bad, IMO.
Another marketing trick is to multiply the short circuit current by the open circuit voltage (unrealistic since these conditions will never occur at the same time ) to inflate the "watts" number.
Also beware of amorphous panels (cheap but they degrade relatively quickly; expect 18 months in constant use then 20% or more efficiency drop). I would recommend starting with the goal zero specs (size, material and construction) and getting things as close as possible that cost less.
If people go with low cost (chinese) inverters find out or measure the idle current (I always switch mine off when not in use). Also some 110 volt LED bulbs, and I expect other devices, show a definite preference for different inverters efficiency wise.
Be aware that chinese inverters sometimes self destruct (had one emit magical brown smoke a couple of years ago) and are sensitive to near miss lightning strikes, lost 2 at different times (get and bring a spare).
Enjoy!
Originally posted by James.
View Post
Beware of low cost solar panels they often cannot meet their own specifications; experience shows that. a small (6 x12 inch, physical size) panel will probably not supply 20 watts, (4 amps for 5 volt systems). I have some, much larger than 6"x12", that are rated at 7 to 10 watts (12 volt system) that actually put out 3-4 or thereabouts. a more realistic output for a 6" x12" panel in a 5 volt (USB) system would probably be on the order of a watt or 2 (possibly much) less.
Especially Chinese, but also other manufacturers/marketing departments inflate their numbers and or/use calculation tricks to get impressive specs (a 5 volt panel outputting .5 amp (500 ma) for 8 hours could be said to supply 20 watts per day (the advertising will probably leave off the per day) .5 X 5 X 8 = 20 although actually .5 amps x 5 volts is 2.5 watts. NOTE; 2.5 watt hours per hour into a USB output is ain't bad, IMO.
Another marketing trick is to multiply the short circuit current by the open circuit voltage (unrealistic since these conditions will never occur at the same time ) to inflate the "watts" number.
Also beware of amorphous panels (cheap but they degrade relatively quickly; expect 18 months in constant use then 20% or more efficiency drop). I would recommend starting with the goal zero specs (size, material and construction) and getting things as close as possible that cost less.
If people go with low cost (chinese) inverters find out or measure the idle current (I always switch mine off when not in use). Also some 110 volt LED bulbs, and I expect other devices, show a definite preference for different inverters efficiency wise.
Be aware that chinese inverters sometimes self destruct (had one emit magical brown smoke a couple of years ago) and are sensitive to near miss lightning strikes, lost 2 at different times (get and bring a spare).
Enjoy!
Comment