my dear friends all around the world!

I'm very interesting about this cool solar power thing, and I really want to start connecting all of my stuff to panels and so.

But for my first and ,hopefully, successful try, I will simply use a simple (apparently not so simple for me, otherwise I wouldn't be here..) solar power bank. No need for charger regulators and other exciting things that might burn down my roof top..

The solar power bank is 20Ah (but I don't know how much watt per hour. The nice seller hasn't replied me yet) -


The camera is 12v/2A and 6-7W, and have to work 24*7 -


That is the question.

I really appreciate your kindly help. A lot.



Note: I really did tried to understand it by myself, but I still have doubts (and those items aren't cheap at all when buying bulks of them as need to). I'm a programmer, so I did have a few lessons in electronics. 10 years ago..

Few of the posts here that help me the most -

Solar panel & battery math verification

Solar panel and 120mm Computer fan

Why isn't the solar panel charging the battery?

Battery recharging via solar panel

  • \$\begingroup\$ 20Ah is a battery capacity. It means it can provide 20A for 1 hour. Or 10A for 2 hours. Or 5 for four. You've got the idea. As it has variable output voltage, it doesn't make much sense, as as higher the voltage, the lower the capacity should be. Generally the capacity in watts per hour will be just the Amps-per-hour multiplied by the voltage. \$\endgroup\$
    – Eugene Sh.
    Commented Sep 1, 2015 at 17:04
  • \$\begingroup\$ @EugeneSh. Well, I think that the sense is that, as you say, although the capacity is indeed lowering, it comes on the expanse of the hours the battery can give us (once again, I'm not an expert. but it did make sense to me). So, you are saying the the Watt per hour, of the cam, is - 12(v)*2(A) = 24W Than it is good for me, since the power bank is 12*3(max A). So, for how many hours can the cam work? \$\endgroup\$
    – roni
    Commented Sep 1, 2015 at 17:19
  • \$\begingroup\$ Anyway, if you are going to rely on the solar energy only, it probably won't work. I don't believe the recharge rate would be sufficient to both power the camera and recharging the battery. \$\endgroup\$
    – Eugene Sh.
    Commented Sep 1, 2015 at 17:23
  • \$\begingroup\$ Note that the output of the battery module is described as "12V/16V/19V/3A", so at 12 volts it should be good for 36 watts. \$\endgroup\$ Commented Sep 1, 2015 at 21:55

1 Answer 1


First thing is to match a solar panel to the load.

You need 7 W, but your panel should be rated for much more, because the average solar energy per day (taking into account the night, clouds and seasons) is a small fraction of the peak power; in the winter in high latitudes you might get 10 to 20 times less. In that case you're looking at a solar panel rated around 100-150 W. If you're restricting yourself to the summer time in bright climates you'd need around 30 W.

The solar panel in the item you posted is said to be 1.5 V, 150 mA. If that's correct, then it can only produce 0.2 W. That is 10-100x too little. No matter what kind of battery is inside, it will never be able to recharge.

Once you have a suitable panel you can start to think about the battery size you need to get you through the night and the cloudiest days. Your camera is a 12V system, which is good because you can buy parts meant for 12V off-grid systems, eg. a solar charge regulator and a battery.

  • \$\begingroup\$ Wow, I wasn't even close.. 10-100 too little :) :) \$\endgroup\$
    – roni
    Commented Sep 1, 2015 at 19:07
  • \$\begingroup\$ Also, thanks for the amazing site you referred me to (off grid solar systems). I wouldn't even think to look to something like this. \$\endgroup\$
    – roni
    Commented Sep 3, 2015 at 5:38

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