Being out and about power and battery life is more and more of an issue. I find myself looking watching the percent icon and keeping a mental tally of my batteries and device levels. A couple of months ago we reviewed and liked the TYLT Energi+, a bag built around a battery, but what is the next step? What if you are going to be away from the grid for a couple of days of more and cannot plug that battery in to charge?

Some might think that it was a good time to use less devices but there is an increasingly viable option instead – solar power.

Sunny Bag Smart Explorer 2 Review: Image of bag and solar panel attached | Ergohacks



Solar panels

The Explorer 2’s main and biggest selling feature is its solar panel. This is removable and unzips along with a pouch to contain its cables or a battery. The pouch has integrated carabiners (hidden normally) which let you clip it onto a different bags or just to set it up in the sun.

The solar panel is designed to let you charge your devices on the go and in good, unobscured, sunlight at the right angle will output about 5 volts at at 5 watts. SunnyBag’s marketing uses their PowerStick battery which has a capacity of 2,200 mAh and shows it charging in ideal circumstances in about 3 hours. In the indirect light it takes between 5 to 10 hours and in the shade between 13 and 20 hours.

My less than scientific testing bore these figures out. A 4,200 mAh battery charged completely in around 5 and a half hours with perfect positioning in direct sunlight. The same battery charged around halfway after spending most of the day in the shade and not at at all when left in a room with no exposure to sunlight.

The upshot of this is that if you have a couple of batteries and a stable aligned position you could keep things going indefinitely with no worries about battery power. If you have a imperfect position such as you would probably get on your back you could probably get enough power with a little caution. Finally if you were in the shade the vast majority of the time you could get some power and if you only switched devices on to make use of them could probably get enough power for sparing use.

Many pockets

The Explorer 2 has a number of well-designed pockets. Starting from the bag closest to the straps is the laptop compartment.

The laptop compartment is divided into three sections. First is the laptop sleeve which runs most of the height of the bag, stopping suspended about an inch from the bottom of the bag to protect your laptop when the bag is put down. The sleeve is elastic on both sides and padded on front and back and has a soft inside. The top of the sleeve has an elastic velcro loop to keep the laptop in place. The front of the sleeve has another suspended pocket with a soft inside which I found perfect for my 8 inch tablet. The rest of the compartment is open and larger and roomier that I thought it would be from the external design of the bag. I found it excellent for paperwork and my laptops charging brick.

Moving forward is another surprisingly roomy compartment which I found ideal for storage of day to day items such as lunch and a couple of water bottles. This compartment has another three large open-topped pockets with soft inside padding. I found if a little more difficult to find obvious uses for these but with a little experimentation the Buffalo Extreme Ministation I’m currently reviewing and my mifi fit into one and my kindle into the other. On the other side of the compartment is a zip up net pocket that runs half the length of the bag. This pocket was ideal for a couple of cables.

Moving forward again is another small pocket on the front of the bag which was good for my notebook and sunglasses in a case.

To the left and right of the Explorer 2 are two identical zipped pockets that zip along the top and then down one side opening surprisingly wide. I was able to put a small water bottle into each of these pockets and close them up most of the way and the zips stayed where I’d put them. This had the obvious advantages of putting water in an easier to access position and meaning that any leaks were on the outside of the bag.

Finally is the solar panel section. This is removable and when removed reveals a hidden bungee cord that can be used to attach a coat or something similar. The removal zip is very well designed being tucked under the solar panel when it is attached to the bag and being of a different color, shape and size to every other zip on the bag making it very unlikely that it would be removed accidentally.

The solar panel section unzips and folds completely open. Inside are three mesh compartments – 2 smaller one large and the integrated USB port that comes from the solar panel. The mesh pockets are just large enough to fit a small battery, a phone and a large battery and when zipped up all are held tightly even when you bounce the back up and down.

Rain cover

The Explorer 2 has one hidden feature that seems a little counter-intuitive. At the base of the bag is a single zipped pocket that contains a removable rain, dust and mud cover. The bag is made out of a high denier nylon and is fairly waterproof even without this and the raincover is designed more to protect the solar panel. The panel is waterproof to a large degree but if it gets dusty, muddy or obscured its energy generation ability goes way down.

Comfortable to carry

No matter how well specified a bag has to be comfortable to be practical. The Explorer 2 is reasonably comfortable to carry – the straps are well shaped and well padded throughout and the back panel has well-sculpted foam padding. Both the straps and back use a breathable weave of nylon that wicked sweat away quite well. The ends of the strap adjusters have nice big loops so are easy to grab and use and are unlikely to unravel.

There is no chest or waist strap and this fits in with the bags target market as a tech commuter bag. If you want to go further hiking or camping the straps would probably not serve well enough but in that case, you could take the solar panel off and attach it to another bag.

Mobile office

The Explorer 2 has all of the obvious requirements for working well as a mobile office bag. Laptop and tablet pockets. Individual pockets for smaller electrical items. Space for snacks and books and enough padding to keep it all safe. The bag would work well for this even without the solar panel and with it makes a very viable mobile office choice.

Target Audience

The Explorer 2 is a little schizophrenic in its target audience.

One one hand it promises the ability to get away from the grid and still keep your phone or camera working but on the other, it is very much a tech bag that lets you carry a large laptop which could never be charged by the solar panel.

It manages to split these personalities with the clever move of making the solar panel removable to attach to another bag. On a normal commute or day out you have the extra charge for your USB devices. On a longer trip away from electricity when you will probably not want your laptop to remove the solar panel and attach it to your larger rucksack or Burgan.

Environment and social responsibility

The idea of charging or topping up our gadgets via solar energy is not a new one but is one that is obviously environmentally friendly. SunnyBag has taken this several steps further and is working with the WorldBank in Ghana and Burkina Faso distributing micro solar systems for miniature businesses. The program is a pilot and if it works out will be expanded significantly.

The idea: portable solar systems as a basis for an own small business

A portable solar system costs around 25 Euros. Within 50 days and 2 mobile charges a day, the initial investment pays off. With day 51, the business man/business woman earns money from the own business.

Sunny Bag Smart Explorer 2 Review: Image of internal bag pocket | Ergohacks


Laptop pocket size: optimised for 15 to 17″
Size: 42 x 32 x 22 cm
Capacity: 25 litres
Item Weight: 1.4kg (including solar panel)
Solar panel technology: Monocrystalline panels
Solar Panel power: 500 mWp
Solar Panel Output: 5v
Textile:1680D ripstop Nylon
Color: Black

Warranty: SunnyBag has a 30-day return policy and a detailed repair service that can fix many electrical problems with their bags.


The Explorer 2 outputs direct charge at 5 volts. This should be compatible with the vast majority of phones and tablets built in the last 5 years but if your device is older or unusual it is worth checking before plugging in! If it is an issue it may well be possible to use the SunnyBag to charge a battery and then that to charge the device.

The SunnyBag is manufactured and sold in the EU. They do ship worldwide but any customs fees would be the customer’s responsibility.



With the exception of the logo, the Explorer 2 is entirely black, inside and out.

The solar panel has no LEDs indicators, colours or lights.

The bag is therefore extremely accessible for someone with any visual problem from any level of impairment to hypersensitivity. The different sections of the bag are textured slightly differently and I was able to use it in the dark with no problems at all. There is, however, one exception.

The exception is less about the bag itself and more about the idea. Solar panels work best in bright sunny conditions. If you have a problem being outside in bright conditions then the bag is unlikely to be able to get enough light or time in light to provide much meaningful charge and so this is probably not the bag for you.


The electronics of the Explorer 2 have no microphone or speaker and are totally soundless.

The bag is near silent in use and uses quiet zips for most of its fittings. There is a single piece of velcro on the ‘over the top’ strap of the laptop pocket.

The bag is accessible to anyone with hearing loss or hypersensitivity of any type.

Input and touch

The bag is made entirely from a high denier nylon but the weave and the feel varies. This goes from a very solid feeling base to four different styles that make up the outside of the bag. Internally it varies between a very soft weave inside some pockets to a light smooth weave used as an internal skin.

None of the weaves used feel rough or unpleasant to the touch in any way.

The zips are all large toothed and have very large pulls. These pulls have two large attachment points and a plastic cover and could easily be modified to add even larger paracord loops or possibly made more ergonomic to a specific user with Sugru.


The Explorer 2’s electronics have no controls or adjustments at all. Plug the battery or device to be charged into the USB port and if there is sufficient sunlight it will charge. A number of nibs are included with the bag including microUSB, miniUSB, older style Nokia and Samsung, 30 pin Apple and a 3DS nib. There is no Lightning cable connector but it would be very easy to plug in your own.

Ease of use

The Explorer 2 is easy to use. I found that the best way to get the most power out of it was as recommended – keep a battery inside it being charged and then use that battery to charge my device. This does lose some efficiency but it means that you don’t have to keep your phone inside the bag and can charge the whole time.

The only difficult part of the system is that to get good energy use from the panel it needs to be pointed straight at the sun. If it is at an angle you get rather less power and if it is not pointed at the sun little to no power. I found it easy, once I remembered, to put the bag down facing the sun when I stopped but when I was walking it was much more difficulty – I could not walk a different direction just to get a better charge!

One possible solution might be to detach the solar panel and affix it to a different part of the bag or your body. If you are walking in a straight line you could thus get the best possible angle. Similarly, if you are stopped and camped or just going to be somewhere for a while it might be worth detaching the panel and setting it up in the perfect position.


Social Interaction

You would not think of a bag as being something that can cause social interaction but the Explorer 2 might be the exception that proves the rule. The Explorer arrived early on a Saturday morning before I was due to go out for a family weekend. We were planning to spend most of our time outside with the sun shining it seemed an excellent test. I kept count and on the first day I was asked by five separate people if that was a solar panel on my bag and how well did it work?

This is an unusual bag and not a bag to wear to blend into the crowd.


The Explorer 2 is made of 1680 denier ripstop nylon. If you have a nylon allergy it should be avoided but most people are unlikely to have an issue.


Sunny Bag Smart Explorer 2 Review: Image of sunnybag heads | Ergohacks

Product Information

About SunnyBag

SunnyBag the company was started in 2008 when founder Stefan Ponsold got a new iPhone and was very unhappy with its battery performance. After a lot of experimentation he came up with a phone cover with an integrated solar panel but while this worked technically it meant you have to leave your phone in the sun for a long period of time – not very practical.

His family runs an upholstery business and with a little help, he was able to stitch the panel into a bag which was far more sensible to use. The company launched their first commercial bag in 2011 and have expanded their range and grown quickly ever since.


RRP 149 Euros or $161.00
Retailer: Amazon for £141


Included in the box

SunnyBag Smart Explorer 2 Solar backpack
USB to charge point cable with numerous interchangeable tips
Quick start guide detailing best use of the solar panel


After a couple of weeks carrying the Explorer 2 around I still, find myself a little confused by it. If I was to ignore the solar panel I’d recommend this bag for daily commuting in a heartbeat. It is very well made and protective of the devices inside it and allows for just enough internal organisation without going down the many pocket rabbit hole.

The solar technology is impressive and works as advertised but I found myself just not getting enough outside sun time on a normal day to make it worth using. Conversely, if I’m going to be spending lots of time outside, hiking or just out then I probably will not need to carry my laptop with me.

I said earlier in the review that the bag was a little schizophrenic – it is two things that don’t quite line up. With a little adjustment of thought, I was able to make it work. Think of the Explorer 2 as a great commuting tech bag and a separate solar panel charger. The two can often be used together but they do not need to do so. If you are looking for a good tech bag and for an off the grid charging solution it can be highly recommended.

The review is based on the SunnyBag Smart Explorer 2 Solar backpack kindly provided by SunnyBag.