Gratzel Solar Backpack 2

G24 Power GCell Gratzel Solar Backpack 2 Review

Backpacks are a very individual product. I’m shaped differently to you and you probably want to carry around different things to me. I have a five year old and don’t go anywhere without wetwipes and hand wash, you find your lipgloss essential to daily life.

There are a few things we can agree on – something that’s comfortable, spacious and looks good. I’d suggest that something protective is also important. If you’re into tech something to keep your gadgets safe and charged would also be big bonus.

The G24 Power GCell Solar Backpack 2 tries to hit all those requirements. The easiest way to summarise the bag is a laptop bag with space to carry your everyday carry and a built in solar panel and charging system. I’m going to look at these two parts separately – as a bag and as a charging system to keep your gadgets going.

The bag itself is made of double skinned high denier nylon in a dark color described as Iron Grey but I’d call it more like a midnight blue under most lighting. It’s somewhat waterproof although I found it leaking slightly around the top zip after around an hour in heavy rain.

It’s got four major pockets. First is the laptop sleeve that that takes up to 15 inch laptops and has padding on both sides. The sleeve pocket is hidden under the straps on the back of the bag and cannot be opened when you’re wearing the bag which is a nice security bonus.

The main and largest pocket is a single open space with two half height open top compartments and a single zip pouch on one side. The compartment has padding on both large sides and unzips to halfway down the bag. The left side of the bag has a single half height zip pocket that opens on two sides and has a single open top compartment inside it. Finally there is a large organisation pocket on the back of the bag that opens to show a number of zipped, open and mesh compartments as well as allowing access to the back of the solar panel. The organisation pocket also has the USB cable coming from the solar panel which plugs into the provided battery. GCell also throw in a small pencil case made out of the same nylon as the outside of the bag which can help you organise your stuff.

The bag has single padded handle on the top and two standard straps on the back. The straps are padded on the top and reinforced with material that can best be described as car belt material. There is a adjustable and removable chest strap and an unpadded and unremovable waist strap. The back is padded with a single large sweat absorbent pad that works reasonably well but isn’t an ideal shape for encouraging airflow.

All in all it’s a decent commuter and everyday carry bag although I’d not be comfortable with it hiking long distances it’s well designed for its target market.

That’s the bag – what about the built in charging technology? GCell use the sensible route of having the solar panel charge a battery which can then be used to charge your device. GCell specialise in solar panels and electronics and it shows. I’ve used solar panels before and the DSSC solar panel is the most practical I’ve used.

I’m not going to blind you with the science of how DSSC works but the bottom line is that in small scale uses like on a bag they have a very low cutout limit. That means that it gets power and can charge the battery at a very low level of illumination. The brighter and more direct the sunlight the faster the battery will charge but it will charge in indirect sunlight, on overcast days and even to my surprise through a window and with indoor lighting.

I tested the bag in numerous lighting levels and although I was restricted by the fact it was February in the UK I found the level of charge actually useful. The battery is 5000mAh and when I left the bag in the sun inside a window for day it charged around half way. On my back outside for around 4 hours on a somewhat overcast day took it from empty to again around half full.

The battery can also be charged via a standard microUSB and can top up from the solar panel and this is the way I’d recommend using it usually.

Gratzel Main pocket

Product Information

Price: £80

Included in the box: Gratzel Solar Backpack 2, removable battery, pencil case pouch

Retailer: GCell +:

About G24 Power

G24 Power is a Welsh firm that specialises in making and researching DSSC Solar cells. They have a factory in Newport and currently make around 500,000 metres of large GCell modules a year. The majority of these cells are used by other OEMs but G24 Power make some of their own products under the GCell name. This includes things like an iPad Air folio case and bluetooth keyboard.

Gratzel organisation pocket

The Ergohacks Evaluation


The Solar Backpack 2 is versatile. I’ve gotten good use out of it as a tech daily carry bag and it would serve most commuters well with space for tech, lunch and a change of clothes for the gym.  I’d have liked to have an extra external pocket for a water bottle on the side but that’s a personal preference and there’s nothing stopping me keeping a water bottle inside instead. The back padding is thick but only a single unsculpted shape and it’s this and the lack of reinforcement on the straps that would make me hesitate to recommend this as a long distance hiking bag.

The back of the solar panel can be accessed via an internal zip but is not removable.

Ergonomic Design

The bag is surprisingly comfortable to wear and when properly cinched up does well on a bounce test with little shaking. The top grab handle is well padded and solid but as with main straps I’d be a little concerned about long term wear if you put it through very heavy useage.

Environment & People

If you are buying a bag with a solar panel in it chances are that you’re either worried about your environmental impact and looking to get some positive energy from the sun or you’re planning to get away from a plug. The Solar Backpack serves these desires well but what about the impact of manufacturing the solar panel itself? Solar panels are traditionally energy intensive to make but DSSC is the least impactful type. G24 power state that the payback is measurable in months rather than years and uses a relatively low amount of rare materials.

Once it gets to the end of its life DSSC solar panels are recyclable. The bag is made of nylon which is theoretically recyclable but there are very few places that can recycle it and the battery is lithium ion which is also recyclable although again it is rarely economic to do so.


Solar powered bags are a relatively new addition to the bag market and seem to range between the level of £60 and £150. The Gratzel fits well into this range with its £80 cost although it’s slightly deceiving as the use of DSSC is something you’d usually find at the higher end of the market rather than the midline.

Durability is harder to tell with a months testing but I’ve put the bag through the wringer and it’s held up well thus far.


Technical Specification

Solar Panel Type: Dye Sensitized Solar Cell (DSSC)
Solar Panel spec: Power .5W Minimum
Solar Panel Operating input current: 100mA
Solar Panel Operating Voltage: 5.5V

Battery Capacity: 5000mAh
Battery output: 1.1A at 5V

Bag Material: 1680 Dernier Nylon outer 150D Polyester Lining
Capacity: 21l
Compartments: 12
Laptop compartment: Yes, 15″ laptop maximum
Chest Strap: Yes
Colour: Iron Grey
Extra: Zipper Pouch


A bag with a solar panel has one obvious requirement for generating power – access to the light. If the bag is in the dark or you’re not going to generate any charge. If you are indoors you’ll get some charge or outdoors and it’s overcast or you’re in shadow you will get some charge. To get a significant amount of charge you need direct sunlight and you need it for a reasonable period of time. The battery built that the solar panel charges into outputs at a maximum of 1.1A which is sufficient for charging most phones but will not handle a larger device such as a iPad.

Grazel Laptop pocket


Backpacks are a very personal item. What we want from them is different for everyone. The GCell Gratzel Solar Backpack 2 is reasonably sized and comfortable tech bag with the additional bonus of being able to generate you power. If you’re looking to go totally solar powered on your devices you’re going to be disappointed but if you want something that can top you up on the go and in a pinch keep you running you’ll find what you’re looking for. If you’re an environmental techie this’ll be right up your street at a reasonable price. Recomended.

The review is based on the GCell Gratzel Solar Backpack 2 kindly provided by G24 Power. This article was first published on the 25th February 2016

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