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Portable solar panel comparison

nicklmg
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Nekteck 20W Solar Panel
Amazon: http://geni.us/ts0L

 

Anker 8W Solar Panel
Amazon: http://geni.us/O3lk

 

Goalzero 7W Solar Panel
Amazon: http://geni.us/awbwqQH

 

Biolite 5W Solar Panel
Amazon: http://geni.us/utun

 

Allpowers 8W Solar Panel
Amazon: http://geni.us/pfxK

 

Can you strap a solar panel to your hiking bag and charge your phone while gallivanting through glorious nature?

 

 

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you're correct that 5 V @ 1 A  does not = 7 W. however the rating of the panels themselves will have the rating of the given Watt figure. there will be some losses in the charging circuits for the ports and each port is probably current limited to 1 amp.

other things to note is that although solar panels like direct sunlight they don't like heat with efficiency dropping off quite reasonably as they get hot.

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P = U x I , anyway... the big one has monocrystal panel.. thats why its better its not all about the size... but yeah... its a waste of money to have it on your back xD

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43 minutes ago, -Old-Tom- said:

there will be some losses in the charging circuits

Probably more due to the inefficiency of the DC boost coverter. The fact that they are all always on 5v is that there is one...

So if we check: (5V*.94A)/8W ~ Only 60% efficiency... Ouch

But then again, it's also possible the full 8w aren't used (since those step up boards have a maximum amperage)

or the USB meter isn't precise, which is often the case.

 

It was a very nice comparison video though!

I'm planning however not buying one, but making one myself...
@nicklmg

Maybe that's also an idea for a future video?

You'll need:

-some 6x6" solar cells (in bulk: http://www.aliexpress.com/item/Hot-Sale-10pcs-4-4-W-18-18-2-high-efficiency-156-Mono-monocrystalline-Solar-Cell/32599982132.html?spm=2114.30010308.3.11.OzRagM&ws_ab_test=searchweb201556_0,searchweb201602_2_10037_10017_507_10032_401_10040,searchweb201603_6&btsid=6df2a310-e1b2-47b2-961b-961f8466aff8)

-some 5v dcdc boost converters (in bulk: http://www.aliexpress.com/item/J34-Free-Shipping-5pcs-lot-New-1A-3V-to-5V-DC-DC-Converter-Step-Up-Boost/32578758991.html?spm=2114.30010308.3.11.Opg66f&ws_ab_test=searchweb201556_0,searchweb201602_2_10037_10017_507_10033_10032_401_10040,searchweb201603_6&btsid=b649a499-a13f-4624-a97a-18308cca29e0)

-A soldering iron (and solder)

-Some wire

-female usb ports (http://www.aliexpress.com/item/IMC-Hot-20-Pcs-USB-Female-Type-A-4-Pin-DIP-Right-Angle-Plug-Jack-Connector/32338586808.html?spm=2114.30010308.3.11.SVgWyS&ws_ab_test=searchweb201556_0,searchweb201602_2_10037_10017_507_10033_10032_401_10040,searchweb201603_6&btsid=1cb5ed4b-a620-472a-b1c6-0c3291a3fcb3)

To do:

You should wire 2-3 cells in series (to add up the voltage, so that it can be recognized by the boost converter), per cell, you will add 4-ish watts in ideal situations

Connect the outer ends to the boost circuit, to which you have added the usb ports

Make some sort of housing out of a see-through material, you can be creative!

 

You could make 3 to 5 of these panels (depends on 2 or 3 cells) for under 50 CAD in parts.

That would be a hell of a comparison video!

I'll try to find some guide online which explains it better.

The point being: It's really not hard (you can even skip the soldering by buying these boost converters WITH usb ports (http://www.aliexpress.com/item/New-DC-DC-Converter-Step-Up-Boost-Module-3V-To-5V-1A-USB-Charger-For-MP3/1179139785.html?spm=2114.30010308.3.21.e7AhhU&ws_ab_test=searchweb201556_0,searchweb201602_2_10037_10017_507_10033_10032_401_10040,searchweb201603_6&btsid=a0d5dd39-768f-4cf7-be09-c0c14ca05c5e)

and by simply using alligator clips instead of wire (http://www.aliexpress.com/item/1set-10pcs-Alligator-Clips-Electrical-DIY-Test-Leads-Alligator-Double-ended-Crocodile-Clips-Roach-Clip-Test/32580823346.html?spm=2114.30010308.3.1.jUh6Ca&ws_ab_test=searchweb201556_0,searchweb201602_2_10038_10037_10017_507_10032_401_10040,searchweb201603_6&btsid=9d2bc5b8-a7c4-4e2f-823c-7dbaac0f9718)

 

This instructable explains it quite good, but uses very week solar cells

http://www.instructables.com/id/DIY-Solar-Phone-Charger-5-Portable-100-Batter/

 

NOTICE:

You will only get 5W of charging power PER STEP UP CONVERTER

If you would use all solar panels in one charger (5 series, 2 parallel I would suggest), you will need to use multiple boost converters to take advantage of the extra power

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There's monocrystalline and polycrystalline solar panels - poly are cheaper to make but less efficient, mono have better efficiency but are more expensive and don't tolerate heat as well as the poly ones.

I suspect all those panels in test were the same..

 

As other youtubers said, the 3 panels in that larger product may actually be able to give you in total 20-21 watts in ideal conditions, full sun directly above the panels (or panels aimed at the sun) .. the manufacturer advertises it as a 20w product because the panels are rated for that, not because it can actually send 20 watts to whatever you plug in it. It's a bit misleading, I know. But, at least that one has two usb ports and in theory you can charge 2 devices at same time with 0.5a-1a or something like that.

The one with three panels is also better because due to the larger overall surface, it will be able to output enough voltage and current to keep the boost voltage converter chips functional in shadowed/darker area  - where the other products will run only at 0.15A, this one will keep working at a decent level.

 

And like it was said above, the boost/SEPIC regulators (probably one for each usb port) have their own efficiency, which may vary between 70% and 90% depending on the amount of light hitting the panels. If the three panels in total give you 21 watts, you'll waste at least a couple of watts due to conversion efficiency.

I

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@SandersFlor the DC regulation was kinda what I meant by charging circuit. and it depends what sort they are using to how lossy it will be.

when i mentioned about the solar panel efficiency dropping off with temperature some quick googleing shows that it would not be unreasonable to expect a 20-30% (possaably more) decrease in power output as if their camera started complaining about the temperature i imagine that the ambient temperature would be in the region of mid to high 30s (°C) putting a solar panel in direct sun around the 50-60°C mark.

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Yeah, solar cells are much more complicated than this. Not only do you have issues with the DC-DC converter efficiencies the others eluded to, but also how you load the cells.

The figure below should give you an indication as to why you are not getting 20W power from the big pack.

So, the system has to be loaded with the right voltage and current in order to work most efficiently.

article-2013november-maximizing-output-s

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There is also another factor may affect the current, the charge state of the device you charging. It is better to use a dump load to test the maximum power output. The charging circuit of the device will regulate the current base how much it need. 

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On 6/14/2016 at 8:57 PM, -Old-Tom- said:

DC regulation was kinda what I meant by charging circuit

Already guessed that :-), but wanted to make sure...

On 6/14/2016 at 8:57 PM, -Old-Tom- said:

20-30% (possaably more) decrease in power output

Yes indeed, most of them are at least 75% or more efficient...
This means they are not able to use all the power, if there would be ideal conditions...

But since ideal conditions pretty much never occur, they have a really nice solution...
 

On 6/15/2016 at 7:11 AM, Rydec said:

There is also another factor may affect the current, the charge state of the device you charging

Pretty sure they took that into account... The tests in direct sunlight all showed maximum power...

On 6/14/2016 at 11:08 PM, RBMDragon said:

The figure below should give you an indication as to why you are not getting 20W power from the big pack.

So, the system has to be loaded with the right voltage and current in order to work most efficiently.

Indeed, we didn't take into account that the heat might make up for non-ideal situations...
So overheating might drop the powering capabilities of the panels...

 

On 6/15/2016 at 3:22 AM, Alphabloom said:

EnerPlex Kickr IV

Well that's quite big and expensive for the minimal output... Where would you mount it?

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21 minutes ago, SandersFlor said:

Well that's quite big and expensive for the minimal output... Where would you mount it?

backpack

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11 hours ago, Alphabloom said:

backpack

In the video that doesn't look like the best idea...
With the large surface it should be able to catch a decent amount of light though.

Make sure you mount it as much as possible on top of your back pack...

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