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Creating a small travel solar kit.

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  • Creating a small travel solar kit.

    I'm looking to make a small and lightweight kit for travel. It must be able to work in hot and humid tropical climate.


    Something small, somewhere in a 5-12w range. I want to purchase a flexible, waterproof panel, and be able to charge a small portable battery (like an anker). Something that's probably just one sheet I can stick in a pack and take up hardly any room.


    It's a little hard to find a supplier with a reasonable price, or instructions on how to do it. Can anyone help me?

  • #2
    Have you checked Amazon or eBay?
    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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    • #3
      Ditto Amazon and Flea Bay are full of that kind of junk, errr I mean equipment. But I can tell you this. At that power level is not even quite enough for a cell phone. 20 watts minimum for a cell phone and even that small small can take a couple of days to recharge a phone.
      MSEE, PE

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      • #4
        Originally posted by Sunking View Post
        Ditto Amazon and Flea Bay are full of that kind of junk, errr I mean equipment. But I can tell you this. At that power level is not even quite enough for a cell phone. 20 watts minimum for a cell phone and even that small small can take a couple of days to recharge a phone.
        some phone you have there: 20W x 8hr of sun shine x 50% efficiency = 80 Wh 80Wh / 3V = 27Ah My own phone battery is 10 times smaller

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        • #5
          Originally posted by max2k View Post
          some phone you have there: 20W x 8hr of sun shine x 50% efficiency = 80 Wh 80Wh / 3V = 27Ah My own phone battery is 10 times smaller
          It's not the phone, it's the sales juice on the solar panel. 20W for only 20 minutes a day. As the sun moves in the sky, the atmosphere soup reduces power, so your harvest is really only effective from 10am - 2 pm, Unless the panel is aimed properly, it will produce less power. And the controller and batteries all have loss, so it will take much more time than you think to recharge

          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

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          • #6
            Originally posted by Mike90250 View Post

            It's not the phone, it's the sales juice on the solar panel. 20W for only 20 minutes a day. As the sun moves in the sky, the atmosphere soup reduces power, so your harvest is really only effective from 10am - 2 pm, Unless the panel is aimed properly, it will produce less power. And the controller and batteries all have loss, so it will take much more time than you think to recharge
            Right and I accounted for that: 8hrs = 2 days x 4 hrs each as well as 50% efficiency. I'm just trying to show OP needs to be more precise in what he wants to get at the end, it's very easy to go overboard at these levels of power. My own phone is 2.2Ah so doing this in reverse: 2.2Ah x 3.3V = 6.6Wh of charging energy. If I want to accomplish this in 20 min at 50% efficiency I'd need 6.6/0.33/0.5 = 40 Watt PV source for 20 min or 20W for 40 min but of course nothing else could be powered up on top of that while phone is charging.

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            • #7
              Originally posted by max2k View Post

              some phone you have there: 20W x 8hr of sun shine x 50% efficiency = 80 Wh 80Wh / 3V = 27Ah My own phone battery is 10 times smaller
              There is your problem, all your math is make believe. No place on earth receives 8 Sun Hours in a day. Well maybe up high on a mountain southside tree line altitude with full view of the horizon on a clear dry cold day near the equator. With a 20 watt panel and switch mode converter to USB 5 volts may get you 30 to 40 WH if you could get horizon to horizon sun at the correct tilt angle. That usually does not work out that well in the field, so you end up compromising and take your losses.

              MSEE, PE

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              • #8
                Originally posted by Sunking View Post

                There is your problem, all your math is make believe. No place on earth receives 8 Sun Hours in a day. Well maybe up high on a mountain southside tree line altitude with full view of the horizon on a clear dry cold day near the equator. With a 20 watt panel and switch mode converter to USB 5 volts may get you 30 to 40 WH if you could get horizon to horizon sun at the correct tilt angle. That usually does not work out that well in the field, so you end up compromising and take your losses.
                But a pretty common situation. Most folks have no idea or concept of resource availability or limitations. Most of the assumptions are about linear availability and most all of those will lead to design problems.

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                • #9
                  Originally posted by Sunking View Post

                  There is your problem, all your math is make believe. No place on earth receives 8 Sun Hours in a day. Well maybe up high on a mountain southside tree line altitude with full view of the horizon on a clear dry cold day near the equator. With a 20 watt panel and switch mode converter to USB 5 volts may get you 30 to 40 WH if you could get horizon to horizon sun at the correct tilt angle. That usually does not work out that well in the field, so you end up compromising and take your losses.
                  nope, that math was for 2 days, 4 hrs each- based on your estimate of taking 2 days to charge the phone.

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                  • #10
                    Originally posted by max2k View Post

                    nope, that math was for 2 days, 4 hrs each- based on your estimate of taking 2 days to charge the phone.
                    Even getting 4 hours of useful sunlight for 2 days straight may be an uphill battle unless the panel it flat and pointed directly at the sun and not moving . More than likely one of those small portable panels will generate close to (not at) it's nameplate wattage for about 1.5 hour at most.

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                    • #11
                      Originally posted by SunEagle View Post

                      Even getting 4 hours of useful sunlight for 2 days straight may be an uphill battle unless the panel it flat and pointed directly at the sun and not moving . More than likely one of those small portable panels will generate close to (not at) it's nameplate wattage for about 1.5 hour at most.
                      I tried to bury those details in 50% efficiency in my estimate. Let's just admit SK has some mighty phone over there .

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                      • #12
                        Originally posted by max2k View Post

                        I tried to bury those details in 50% efficiency in my estimate. Let's just admit SK has some mighty phone over there .
                        He might.

                        But all kidding aside, most of those little portable solar panels cost a lot of money and will not provide a sufficient charge.

                        IMO it would be cheaper to get a couple of those 10,000mah lithium battery packs that are small (4 x 2.5 x 1 in) , relatively cheap (< $30) and very light ( 7 oz).

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