Yes, its that time of year again where we get the first encouraging days of sunshine in Europe so I’ve been into the cellar and dusted-off my Sunlinq 24W solar panel.

 
Sun strength for the last 2.5 days.

I’m not planning a solarumpc tour this year but I am planning to get some use out of the panel. At the moment, the plan is to run a UMPC from the solar panel that could serve this blog. I doubt i’ll be able to do it 24/7 for the whole of summer but I’m running some tests on the Raon Digital Everun S6S at the moment to see exactly how much I could get out of it with the 24W panel.

The Everun, when configured for 400Mhz with WIfi and screen off, will consume a tiny 4W at idle and about 6W at full power which is about as low as you can go with a PC without having to switch to an ARM architecture. I don’t want to do that because the plan is just to install a basic Ubuntu image, fire up Apache and SSH and serve this blog as a set of static web pages. WIthout Mysql or PHP running it should keep the processor load down to a minimum although i’m not sure that Ubuntu will be able to switch the CPU into 400Mhz mode. It might have to stay locked at 600Mhz.

At 5W drain, the server would need 120Wh of energy to power it for a full day. With a 24Wh panel I’m only going to get about 80-100Wh per day on average (using the 4-hours sun/day  rule that applies to this part of the world) so at some point, back-up power is going to be needed. The problem is, how can I switch-over to back-up power (or gracefuly switch over to another server.) Switching the servers is OK but getting the Everun to shutdown when it reaches 5% power is impossible under Linux right now.

The Alternative is to shut-down the server between 0300 and 0900 every day and to try and regulate it that way or just keep topping up the SLA battery from other sources when needed.

I’m going to need a couple of new items for this project though.

1) Power usage measurement tools. I want to feed the data back into the website. Power used, power given by panel, current battery level. Any tips there would be much appreciated. Should I buy a dedicated data logging system with software or are there simpler ways to do this.

2) An ethernet port. The Everun only has a WIfi connection and that would take too much power so I’m looking at a USB to Ethernet adaptor. This one from SMC takes about 150mw which will be fine.

3) Bigger SLA battery. Rather than using the 56whr battery that I have, I should get one that takes about 200wh so that if we have two or three good days of sunshine, I can store the engergy and use it on days where the sun is weaker.

Solar panel positioning is going to be a major problem at my house which is badly oriented for a solar panel. I’m also a bit worried about loss along the length of cable I will need in order to position the solar panel correctly.

Over the next few weeks I hope to at least have a partial solar-powered web server running but if this blog disappears, you’ll know what’s happened!

You might remember that on the Solar Tour last year I used RoboGeo and a Garmin Etrex to enable an internet based track and tagged photo stream. The Etrex would do the tracking and every time I stopped I would download the track, to a UMPC, download the images I’d taken and run them through RoboGeo which would match the timestamps on the images to the position at that time according to the track. I would then export a kml file which would be uploaded to my website and automatically pulled into my Google Map. It was about the easiest way to do it then (see my day-plan for more info on it) but a lot has changed now!

Recently I bought a Nokia N82 smartphone which has built in GPS. Google Maps has been great fun to play with on a phone and even more fun was the beta release of Nokia Maps 2.0 which added satellite imagery, internet search, live traffic and a pedestrian mode. The other application I found was the Nokia Sports tracker. This phone-based applciation does the same job as my old Etrex in that it logs data and shows statistics pretty much as the Etrex did. The best part of it though is that you can authorise the software to send data to an online Sportstracker account, live! Users accessing the current activity on the website can then see your location in real time overlayed on a Google Map. Fantastic! Once you’ve finished your activity the program then goes through your photos looking at the timestamps and offers to upload them all with GeoTags to the same Sportstracker service. With a few simple steps, the track is automatically overlayed with image pointers. Groovy!

Here’s a public ‘track’ I made on SportsTracker.
http://sportstracker.nokia.com/nts/workoutdetail/index.do?id=74767

With one more step, you can export the KML file and import it into a Google MyMap thus breaking it out of the Nokia Sportstracker website and making it easier to share and add mroe info too. There’s one more thing though. I didn’t quite fancy my images being stored at the sportstracker website so I’m using Shozu to auto-tag and upload to Flickr. Using a great tip I picked up from TheNokiaBlog I found out how you can auto-link a geofeed from Flicker and have it show up live on a Google Map. The only thing missing is being able to auto-export the track in the same, live, way from Sportstracker online, or the Sportstracker app on the phone, to Google Maps. I’m sure that will come soon though as it seems like an obvious way to make live people-location mashups and create even more excitement over the location aware possibilities with Nokia phones.

Here’s a map I prepared earlier!

View Larger Map

I’m sure that we’ll see Nokia combining Maps2.0 and some form of live tracking soon. It would be so much fun to see where your friends are and what they’re doing. Can you imagine that in a very short time we’ll be able to link this into live personal video too for the ultimate GeoVideo experience!

One problem with all this is that it takes a lot of battery power from the phone. Where I was getting 20 hours from two AA batteries, the Nokia N82 will last for 3 hours if you set it up correctly using lower-power GSM-based data. If you use 3G data, your battery life will suffer even more and you’ll see soemthing less than 1.5 hours. You might need to take a spare phone with you or turn off the live upload feature which will give you all-day tracking. Even if you upload every time you take a break, its a lot easier than using the manual process I was using before.

Goodbye Garmin Etrex! Goodbye Robo Geo!

It looks like Voltaic will be releasing a 14w solar panel bag, a huge step up from their, largely useless, at least for UMPCs, 4W bad. I hope its not a typo as the three-panel setup look exactly the same as before.

If it really is 14W then I’m interested. Well almost. The design is a little on the ugly side and the price of $559 means I could actually buy a stack of spare Li-ion batteries that, charged, would run a UMPC or one of the new Menlow-based MIDS showing up at CES for a few weeks or more!

This story is from CNet and the author mention in the article that they will be running a story about solar laptops soon. That should be interesting and one to look out for.

Thanks to Matt for the tip.

This setup looks familiar!! Mini PC, Solar panel battery pack. The only difference here to my UMPC setup is that the CPU and screen are in separate units.

The Aleutia E1 is billed as the ‘ultimate off-grid computer’ by the London based company and they also offer the complete solution as an ‘office in a box’ package.

I have a few issues with the package though. First, the PC itself is running on a very low end 200Mhz, unspecified ‘X86’  processor. Secondly, the screen they’re using can take up to 10W. With the PC taking up to 8W, the whole solution seems fairly heavyweight compared to a UMPC-based solution.

I’ve just been testing an HTC Shift which has the 7″ 800×480 screen and can run Vista with Aero at an average 8.5w with the Wifi on! The AMD-based Kohjinsha SA1 averages even less and if you managed to get hold of an XO Laptop through he OLPC’s G1G1 program, you’d be averaging something like 3W drain giving you 6-times the run-time of this solution – with twice the processor speed!

On the plus side though, the complete solar office solution comes in at under 500 pounds sterling. That’s not bad at all.

Via LinuxScrew. Thanks Klaus.

It’s nice to see that someone else is as tech mad as me! Scott, currently residing in Cubicle 13, has decided to get out of the rat race for 18 months and he’s taking a UMPC and Solar panel with him.

18 Months! 6 months of that will be on the Appalachian trail!

Scott is taking the ac-inverter route with his solar solution so it will be interesting to see how he gets on. He doesn’t set off for another 78 days so there’s time to get the kit in order!

His first tech task was to buy the Raon Digital Everun that he’s planning to use and get it protected in some way. He’s currently testing out a modified OtterBox.

I’ve promised to help out with the testing. I’m just about to go outside and plug my Raon Digital Everun directly into a solar panel as a test. Luckly I have a spare power board for it so if I get any of that magic smoke, I should still be OK!

Scott’s blog was: Escape from Cubicle 13

Last Thursday I spent a lot of time analyzing exactly how efficient my charging solution was with a real-life test. What dropped out was a rather poor picture of how inefficient the whole solar charging setup was. From over 1.2KW hitting the area of my solar panel I managed to use about 19W. That’s a 1.5% efficiency rate and its amazing that I was able to do anything with it!

Take a look at the diagram again below. it shows the loss-points along the route from the sun to the UMPC.

More efficient UMPCs?

Of course! Any improvement in efficiency here would help. Currently a good average is around 9W and if this could be reduced to 6W average, it would be a major improvement.

Bigger battery life?

No. For my tour, the battery life or battery capacity was really not an issue. 50W/hr per day total capacity (via two battery packs; one that can be used and one that can be charged, is ideal.)

Solar Panel improvements.

From 1.2KW that hit the panel, only 660W hits the solar cells and those cells are only around 8% efficient and this is the first place we can look for improvements.

Current top-end production solar panels are 22% efficient but these are hard panels. To get the equivalent of 25W power you would need a hard panel of about 35x35cm plus frame. Lets say 40cmx40cm in total area. By using a hard panel of this size I could have actually put one on the front and one on the back of the bike to achieve a much more powerful solution. Finding a 40x40cm high efficiency panel might have been difficult though and probably less rugged. There could be a weight consideration too. Given the space restrictions on a bike, I think that a hard panel solution might have been better. In the campsite it wouldn’t have made much difference. The foldable panel was light and small and there should be no need for more than 25W of max power.

Battery tech and charging methods.

There’s a lot that needs to be improved here and the improvements can be achieved through a combination of process and of technology. What follows are the most important issues.

Lead-acid out!

The lead-acid battery proved to be a hindrance more than a help. It was heavy. It had no charge level indication and at low charge levels it couldn’t deliver enough current to drive my DC DC converter or even charge the AA batteries. In short, I didn’t use it much at all and I would drop it from my kit list if I did it again.

Li-Ion problems.

I knew that charging a battery just to have it charge another battery would be inefficient but I didn’t realize that it could be so bad. For example, the Li-Ion battery pack I have (Tekkeon/Tablet Kiosk MP3400) appears to lose about 25% energy through the input and Li-Ion charging stage. That is, you have to pump something like 20% more energy into it than it can store. But that’s not the whole story. The voltage conversion process on the output stage kills another 20% of the energy! From input to output you’re losing a shocking 40% or more energy!

But there’s another problem too and i’ve mentioned it before. The charging of Li-Ion batteries occurs at a fixed rate which means however much energy you have available and however quickly you could feed it into a Li-Ion battery, it won’t take it any quicker than its designed for. The MP3400 takes about 15W (about 0.8A at 19V) of energy to charge it and even if I attached a panel capable of delivering 50W, it would still only take 15W wasting a huge amount of available energy.

This last problem is the one that needs attention when designing a solar charging solution. I have detailed some possible solutions at the end of this article.

Direct charging UMPCs from solar.

One thing that I found annoying was that the only was I could charge my UMPC battery safely was to charge it from the Li-Ion battery. Obviously this is inefficient for the reasons mentioned above but why can’t I charge the UMPC direct from the solar panel? The main problem is that the DC input circuitry on the UMPC is an unknown factor. There’s no way to tell if there is over-voltage protection or whether it will charge a through varying input voltages and its just too much of a risk to try it out. When the DC input on the UMPC is broken, so is the UMPC! I also though about trying to charge the UMPC battery on its own but there’s no standard in connectors or charging currents and voltages so unless you want to build your own charging circuit, this isn’t possible (with the one exception of the OQO Model 02 that has an external battery charger.) I don’t really see this changing much on UMPCs in the near future though. There’s no real reason to increase the complexity of the DC circuit just because Chippy and a few others wish to use solar panels!!

How to improve the solar charging process today…

The Sunlinq 25w panel and Tekkeon MP2400 battery pack is an easy option, readily available and relatively cheap. It works, and if you use the tips above, it can be quite succesful but there are further improvements that could be made, especially if you have the time a flexibility to adjust your solution as you go. Lets assume the lead-acid battery option is too heavy and will not be used.

Ideally you will have the flexibility to add load and add solar capacity as conditions vary. This requires multiple smaller solar panels and multiple smaller Li-Ion batteries that can be set up in different situations. This is currently the only way to provide the most efficient charging solution. Buy multiple slow-charging (500mA for example) Li-Ion battery packs that can be stacked in parallel as energy availability increases.  You will need a voltage regulator on the output of the solar panel and this will need to match the input voltage of your charging solution. Preferably 12V. Fit an ammeter and voltmeter to the output of the voltage regulator so that you can monitor load and voltage. This all takes a lot of time and effort though and for most people its not worth the trouble. Ideally you would have a smart charger that does the monitoring and switches in Li-Ion packs as current availability increases. I have not seen such a solution yet and this, along with some more advanced solutions is what I’d like to see in the near future.

…and in the future.

How about a Li-Ion battery pack that has three levels of charging speed. Low, Med and High. These can be manually adjusted to match the energy available. Ultimately you would have a Li-Ion battery pack that self adjusts to the input current available. I have seen a few advanced components that claim to be able to do this but have never seen a consumer product that is able to do it. If you can get vari-charging Li-Ion batteries then there is really no need for the heavy lead-acid battery at all.

Finally, I’d like to see more UMPCs that have an external battery charger with good, efficient circuitry, over voltage protection and a wide range DC input voltage. Currently there are very few options here.

I’ll be watching this space carefully from now on and I hope that it won’t be long before I can report about new solutions to the issues of solar power and battery charging.

The 102 (good) photos that I took on the Solar UMPC tour have now been posted in the UMPCPortal Gallery.

We (that’s me, VIA and a PR company) had tried to plan a crossing-the-line press meeting today but as it turns out, everyone is at IFA and no-one was available. It was a little disappointing but seeing as it was raining, I’m not bitter! I took the chance to jump on a train home and start the process of writing-up the project. The first think to do was unpack those smelly socks and make sure I had everything listed for anyone that might be interested in the future. The gadget bags were the most important bit unless you want to see a picture of my wash bag. No? Thought not.

It was a well-refined 10-day gadget bag I had with me on the Solar-UMPC tour so as I unpacked a few hours ago, I took the opportunity to update the pack list (Google spreadsheet available here.) and take photos of the solar setup and the computing setup I used when I was out.

First, here’s the solar setup. Most of it is explained in previous posts (see this one and this how-to for example) but maybe this picture helps to simplify how I was using the devices.

The second picture shows the computing setup including the all-important gadget of the week, the USB LED lamp! The mobile phone and UMPC worked well together as a communication suite. The phone took primary role as email reader, music/radio and twitter interface with the UMPC performing the more creative roles with the map updates, blog entries, photo editing and geo-tagging.

The computing set-up was really good and apart from reducing cables and improving software, there isn’t much i’d change in terms of components. The solar setup will defaintely need improving though and as I mentioned in this post about the inefficiencies, I have already made some notes about how I would improve it. I’ll be going through my recommendations for the computing and solar setups in later posts.