Review: Opteka-SC4000 Thin Solar Power Bank

Opteka-SC4000 Thin Solar Power Bank











  • It has a slim, small and lightweight design


  • The Output and Input charging is slow.
  • Solar Recharging is slow.
  • The power capacity is low and isn't going to provide many charges.
  • Not Waterproof or Shockproof. Those are important things for a solar power bank.
(Last Updated On: December 3, 2018)

Solar power banks might sound useful and even though they’re basically more useful than your regular power bank, there are still a lot of reasons why you shouldn’t just go chasing these solar charging devices.

They can indeed recharge themselves through the sunlight and possibly any other source of light, but these kinds of chargers are usually lacking in other areas; like their charging speeds, design and even the solar recharging itself being the main part of the device.

This is the Opteka 4,000mAh solar power bank and although it might look quite sleek and professional, we’ll reveal what it really has to offer in this Charger Harbor review.

Dizaul 5,000mAh Solar Power Bank


Power Capacity:

The power capacity of the Opteka is started at 4,000mAh and that’s not what you’re really going to be receiving because the power bank uses Lithium Polymer batteries that aren’t good at converting their energy and as a result, you’re most likely going to receive an Output power capacity of 3,000mAh that you can actually use to charge your device.

It’s a pretty big disappointment because what was meant to be a power capacity that would provide 2 full charges to your smartphone, this Opteka can only provide 1 full charge to most smartphones like your iPhone 6 / 6s Plus smartphones.

Having a single charge is very true for larger capacity Android smartphones once you’re charging Galaxy or a Google Pixel smartphone.

If you’re thinking that you can charge tablets with this power bank, you can, but it’s not worth it at all since both the power capacity and charging speeds are not going to provide you with a good experience when charging a tablet.

Opteka-SC4000 Thin Solar Power Bank (Output Power Capacity = 3,000mAh)Phone CapacityOpteka-SC4000 Thin Solar Power Bank Left Over Capacity after One Charge

# of Full Charges for the Device
iPhone SE3,000mAh1,624mAh1,376mAh Left Over

1.8 Full Charge
iPhone 63,000mAh1,810mAh1,190mAh Left Over

1.6 Full Charge
iPhone 6 Plus3,000mAh2,915mAh85mAh Left Over

1.0 Full Charge
iPhone 6s3,000mAh1,715mAh1,285mAh Left Over

1.7 Full Charge
iPhone 6s Plus3,000mAh2,750mAh250mAh Left Over

1.0 Full Charge
Samsung Galaxy S63,000mAh2,550mAh450mAh Left Over

1.1 Full Charge
Samsung Galaxy S6 Edge3,000mAh2,600mAh400mAh Left Over

1.1 Full Charge
Samsung Galaxy S73,000mAh3,000mAh0mAh Left Over

1 Full Charge
Samsung Galaxy S7 Edge3,000mAh3,600mAh-600mAh

Need 600mAh of More Power Capacity for a full recharge
Samsung Galaxy S8+3,000mAh3,500mAh-500mAh

Need 500mAh of More Power Capacity for a full recharge

Output Charging:

The Output charging isn’t that fast because it can only Output 5V/1.0A. A 1 Amp charging speed is a slow one and it’s not going to charge most of your USB charging devices at their max charging speeds.

This is true for smartphones and very true for devices that are tablets and smartphones that are compatible with Quick Charge.

Input Charging:

Solar Recharging:

The solar recharging like on many other solar power banks isn’t that fast and when you have the power bank in direct sunlight with light hitting the solar panel, the max recharge rate of the solar charger is 5V/250mA.

That’s basically a Quarter of a single Amp and so if you’re solely recharging the power bank through its solar panel, it will be able to be fully recharged within 12 hours.

However, most of the time you’re not going to fully recharge it from the sun because most of the time it won’t be in direct sunlight and of course, the Opteka can only charge to 75% when it’s being recharged through solar means.

Similar Solar Power Bank

Mini USB Recharging:

Okay, this isn’t’ recharged normally like most portable chargers on the market because you have to use a Mini USB charging cable to recharge the power bank and when you’re recharging the Opteka through the Mini-USB port, its charging speed is 5V/1.0A.

It has a recharge time of 6 hours when being recharged through the Mini-USB Input Port.


Size and Weight:

Even though the power bank isn’t that powerful, it sure is portable because of its small size and weight.

This is because it has a length of 4.5 inches, a width of 3.3 inches and a thickness of 0.5 inches. The weight of the power bank is 6.5 ounces. So it can potentially fit into your pocket if you really wanted it to but it’ll still be a tight fit.

Functional Components:

It’s easy to use with all the functional pieces in the same general area. The USB Output charging port is on a short side and the Mini USB Input is there too. At the top is where you’ll find the power button and 4 Blue LED power capacity indicators. You need to press the power button to begin charging.

Innoo Tech 10,000mAh Solar Portable Charger


Structure and Material:

Not the most durable Solar power bank and that’s really bad because a solar power bank is supposed to have a strong build because the assumption is that you’re going to take this into the outdoors for when you’re camping or hiking.

As a result, dropping the Opteka solar charger can result in damage, and it’s not waterproof at all, so you shouldn’t keep it out in the rain. It’s made of plastic.


The power bank makes of a few of the main safety measures like Short-Circuit and Surge protection. It also shuts off charging once your device is fully recharged.


For the most part, the Opteka is not a reliable portable charger. It doesn’t provide enough Output power capacity to charge smartphones multiple times, the charging speeds for the Output, Input Solar and Mini USB charging are all slow and the build quality is very poor.

You can’t really justify taking this power bank into the wilderness because it isn’t built for that and it can easily get damaged.

Similar Power Bank

Aukey PB-P8 12,000mAh Dual USB Port Solar Power Bank



The power capacity is on the lower end and can at most, charge your smartphone once. Charging speeds are slow and the solar recharging is barely going to be used because it’s so slow.


Probably the best aspect of the power bank because it’s a small and lightweight charger.


It’s not a rugged solar power bank, so it can’t take falls and it isn’t waterproof. Not really meant for the outdoors.


With all of its aspects put into one, the reliability of this power bank solely hangs onto how portable it is because all the other parts are lacking in quality and power.

All Solar Power Bank Reviews

Specs of the Opteka-SC4000 Thin Solar Power Bank:

  • Capacity:            Advertised: 4,000mAh            Output Capacity: 3,000mAh
  • Output:   5V/1.0A
  • Input:    5V/1.0A Via Mini-USB Input Port
  • LED Power Indicators: 4 LED Dotted Power Capacity Indicators
  • Size: 4.5 x 3.3 x 0.5 inches
  • Weight: 6.5 Ounces


The Opteka solar power bank tries but it does have the right amount of power or build quality to even be a solar power bank. It’s great that it can charge through sunlight but that doesn’t mean much when the charging speeds that your devices are going to receive are really slow.

Readers like you help support Charger Harbor. When you make a purchase using links on our site, we may earn an affiliate commission. Read More.