In a recent test I ran a tablet connected to the internet at an average 200 mW. That’s screen off, wifi connected and polling in the background to update emails, location, twitter and other processes. It’s nothing really surprising because most of the tablets are built on smartphone technology. With the screen on though, usage will jump about 5-7x and if you push the CPU and add 3G you can reach 20X that power drain. Still, running everything in 4W is still impressive. It’s just a shame that 20-30% of the in-use power and about 70% of the idle power when the screen is on is used by the screen itself. LED-backlit technology is getting better but only in small amounts. What if you could use ambient light for the screen, just as we do when we read a paper book?

Pixel Qi is one company that are developing these ‘transflective’ screen technologies and in an interesting interview I saw today, Mary Lou Jepsen, the founder, talks about using solar energy to power a low power tablet with a Pixel Qi screen. By combining transflective screen technology with a low power tablet, you’re talking about 1W of power in idle, screen-on situations.

Unfortunately, the 1W panel that Mary Lou shows, isn’t going to be enough.

More after the video.

There are a number of issues here.

1 – No one leaves their devices in the sun unless it is in a secure place. It is usually recommended that devices are not left in the sun at all.
2 – There are, on average during a summer period, about 4 ‘solar’ hours per day in central Europe, rising to about 7, year-long towards the equator. That’s because the sun is only at its strongest for the midday period and clouds and shadows will also impact the overall efficiency.
3 – Battery charging isn’t a simple matter of trickling some energy into a batttery cell. Most Li-Ion battery circuits only trigger charge at a certain level of voltage which again, reduces the number of hours per day that a solar panel can be used
4 – Charging circuitry is innefficient. You can lose 20% of the engery through the charging electronics.

Don’t forget that we tend to be awake and using our devices during sunlight hours and we tend to do that away from the sun so the possibilities for on-device charging are seriously limited.

While a 1W panel sounds like it might be enough, to charge the average tablet (with a 15Wh battery) you’d need to sit the device in the midday sun every day for about a week for a complete charge.
Yes, Pixel Qi screen technology reduces the battery requirements but even with a battery half the size, the time taken and the akwardness would make the process unusable for all but the most niche of cases and even in those cases (off-the-grid, emerging countries) a solar charging station for replaceable batteries is, in nearly all cases, a better idea.

Of course there are some scenarios where this would work today and at some point in the future the cross-over point will be reached where it makes sense to build solar cells into consumer devices. Pixel Qi are definately doing their bit to accelerate this but there’s still a way to go before we see solar panels built into tablets.

It doesn’t stop me thinking about solar computing though and in this post I’m going to compare a set of devices and some technologies that will be important for the job of Solar PC 2010.

Before I do that I want to highlight a few things that really haven’t changed much in the last 3 years. It’s a sad story of minimal progress.

• Solar panels – NOTHING has changed. They’re still expensive and inefficient.
• Battery Tech – NOTHING has change. They are still expensive and use the same technology as before.
• Operating system choice – Nothing has really changed. If you want to work efficiently you need to choose the same OS as you use on the desktop. Mobile operating systems have come a long way but there are still too many potential roadblocks for the average productivity user. Windows 7 is nice but compared to XP it’s less efficient which in my book, makes it the best choice for efficient and productive mobile computing.
• Screen technology. Outdoor users are still fighting the sun with LED backlights although this is a great step forward from the CCFL backlighting I used in 2007. Transflective screens are coming in 2010 though. See below.
• Weather – Ah, there’s something that hasn’t changed much either! Still, constant chaos. (Thank goodness!)

The device shortlist.

Click for more information.

Luckily the computing platforms have moved on somewhat and along with better engineering and components so there are some great contenders out there. Lets take a closer look at the best ones under 1KG. From top left in the images above:

• Viliv X70
• UMID BZ
• Fujitsu U820
• Fujitsu UH900
• ASUS EeePC T91
• Viliv S5
• Viliv S7
• Sony Vaio P-Series

Viliv appears three times in that list and is shows that they’ve done a great job of working around the Intel Menlow platform and producing some amazingly high-quality and efficient UMPCs that are focused on mobile productivity. Take the S7 for example. It has an excellent keyboard, SSD hard drive (rugged) and convertible touchscreen and comes with a built-in 3G option. The 34wh battery can last for 6-9hrs depending on usage. The tiny BZ is even more efficient though. The 17wh battery lasts for 5hrs…online and it comes with an external battery charger adaptor for 9V charging.

ARM-based devices.

You’ll notice that I haven’t included a single ARM-based device or ‘smartbook’ in the list above and the reason is simple. There aren’t any productivity-focused devices available. You might think that the ‘cloud’ provides the answer but the cloud is a long way away from being a mobile solution right now so despite the increased efficiency of ARM-based tablets and notebooks, I’m afraid it’s not a solution for the main computing device. For a smartphone though, yes! It’s the only solution.

Waiting for the screen.

My problem with all of the above solutions now is that I’m aware of two technologies that are close to hitting the market in 2010. Both Pixel-Qi and Mirasol have solutions that can save a lot of power when in high ambient light situations. Up to 1.5W in sunlight on a netbook-sized device. That’s a huge saving in a device that might be using only 6W. A 25% saving is huge and also helps to keep things cool in the device which helps other components too!

The advantage is so, so great that I’d hesitate to buy any device for a mobile tour unless it had the technology included. I’ve tested it and heard that it’s coming and if it hits a netbook soon (likely before UMPC style devices) I would seriously consider it…despite the extra weight of a netbook. 600gm extra weight to save 20-25% energy and to enable full-sun usage is a huge benefit. It also brings a bigger screen and keyboard for even more efficient working.

One of the most interesting 10” devices I’ve seen recently is the Viliv  S10 ‘Blade’. It’s a slick, SSD-based device built on the Menlow platform. It’s one of the lightest 10” devices at 1.2KG and it’s very slim. Once again it looks like Viliv have made it super efficient; the marketing claims up to 10hr battery life on a relatively small battery so I’m wondering…how about an S10 with a Pixel-Qi retro fit which could take it to 12hrs or more. For 1.2KG that’s a huge advantage and if there’s a way to charge a second battery separately, direct from solar power then we’re cooking with gas (as they say.) Oh, i forgot to mention that there’s a 3G and 2.0Ghz CPU option! I have a little worry about the convertible screen hinge but that’s the only potential issue right now.

Smartphones

One thing that has changed since 2007 is the smartphone. The capabilities of a high end smartphone are almost unrecognisable from those of 2006. Cameras, processing power, screens, keyboards, operating systems have all changed for the better and there is serious potential to be doing a lot of ‘microblogging’ work on a smartphone which would increase mobility and save battery life for full-on productivity sessions. I’m a big Google user and the choice of phone for me would be relatively simple. The Android operating system offers a fast, easy and efficient way to access my emails, docs, chats and maps and through the huge number of applications available in the Android market I would have no problem finding easy ways to keep people updated with my location and latest photos. The Motorola Milestone (Eu version of Droid) is clearly the best choice at the moment although the landscape is changing every two or three months here. I’d be looking for a phone with a keyboard, a superb camera and GPS and a large, easy-to-read rugged screen. (The Milestone uses Gorilla Glass) Battery life is of course important but at this level, the differences are unmeasurable based on technical specifications and the limited number of details reviews.

Summary.

I feel a plan coming together but I need to work on that PC solution. 1.2KG isn’t my ideal choice (600gm and a much smaller form factor – The Viliv S7 perhaps) would be better but if that new screen technology hits the ground, it’s a must-have. It just so happens that an S10 sample is coming my way soon (for testing on UMPCPortal) and I also happen to know that there are some 10” Pixel-Qi screen samples knocking about. I think it’s time to give Pixel-Qi a call to see if they want to help out with a new solar computing tour!