Would it be possible to have a 5V/5W solar panel charge a USB power bank (5V/1A USB power bank) using a module like this? My load is powered by USB, which would be directly connected to the USB power bank.

My concern is that a solar panel, as I understand it, only gets to 5V when it is in very bright and ideal conditions. If it is not, the voltage will drop below 5 V and therefore it would be unable to charge the power bank. In addition, the module that I linked to accepts 5V and not less than 5V.

Should I just try to find a buck-up module that can accept lower voltages and force the panel voltage to match 5V (or higher if that's better)?

 

Does your power bank require a 12V input to its charger?
According to the legend on the underside of that module it accepts between 3V and 6.5V

 

USB power bank is straight USB-to-USB charging, which according to the USB specification's is 5V.

I just saw that as well (3-6.5V). Then I would assume it should work then even if it the solar panel voltage drops below 5V.

I read somewhere before that step-up modules are "not as useful/technically efficient" as step-down modules. But for these small voltages it shouldn't be a problem.

 

I read somewhere before that step-up modules are "not as useful/technically efficient" as step-down modules.

Your main problem is with the solar panel. The sunlight that hits the panel is not going to be constant. The best you can do is use a diode to make sure the current doesn't back up through the solar panel when the sunlight is bad.

Here are some good Shottky diodes at 25 cents to 40 cents:
http://www.mouser.com/Semiconductor...Z1yuobnnZ1yuoc7hZ1yuo73fZ1z0y4ci&Ns=Pricing|0

 

Wouldn't the solar controller do this already? That is one of the functions (to prevent current backup).

 

Wouldn't the solar controller do this already?

Which solar controller is this that just appeared?

 

Sorry that I didn't mention this. Something like this.

 

You want to use a controller that only works with 5V and up (excess voltage) to fix a problem about a lack of enough voltage? That doesn't make sense.

 

My mistake. It looks like this controller doesn't accept lower voltages than 5V, just as you said.

In such a case, it would be easier (and cheaper) just to use a diode like you mentioned. Would you be able to give me advice on how to choose the appropriate diode? The page you linked has over 10 pages.

 

The diode needs to be able 1A comfortably, and probably only needs to be able to withstand 5V reverse voltage, but you want a bit of a safety margin. This one will do nicely:
http://eu.mouser.com/ProductDetail/...=sGAEpiMZZMtQ8nqTKtFS/D9SVzsgHTKGsSRnwjiVnSA=

 

The page you linked has over 10 pages.

That's right. Ten pages of diodes that are very generous in their specifications...hundreds that will work...none that won't work...for prices as low as 25 cents. You can print out all ten pages, throw a dart at them from 10 paces, and hit a diode that will work. What kind of help do you want?

 

You can print out all ten pages, throw a dart at them from 10 paces, and hit a diode that will work.

Interesting component selection technique, there.