Tag: solar

Projects

I’ve mentioned before that I’m into solar power, and that there are a couple projects I’m getting into.  Well, I’ve been thinking about a couple things for a long time, but I’m just now starting to get into serious development.  There are two things: a maximum powerpoint tracking (MPPT) charge controller, and a sine wave inverter/charger.  The first of these is a good tool for extracting extra power out of solar panels, while the second is instrumental in interfacing the DC and AC sides of a power system.  That is, the inverter/charger will allow you to get clean AC from your batteries, or charge them from a source already available.  Think computer UPS, but designed for a slightly different purpose.

There are various homebrew projects like these floating around the Internet, and I hope to contribute something.  By posting about these here, I hope that I remain focused on them :).  This should be interesting, and maybe even useful to someone.  I’ll try to give an update here and there as I come up with more of a solid design for both.

Raspberry Pi

I should take my second post of the new year to mention that I love raspberries.  I’m not sure if they’re my favorite, but they’re damn close.  I’m not sure what else to say, other than try some in champagne, or other drinks.  Try them with cakes.  Candy bars containing raspberry are good as well.

This post, however, is not about the berry, but the Raspberry Pi, a tiny embedded Linux system that boasts enough power to be a full-featured desktop.  (If you came upon this post, you’re probably already somewhat familiar.)  There are two models, at $25 and $35.  The more expensive one has two USB ports as well as an Ethernet port.  (The lesser, I believe, only has one USB and no Ethernet.  But, you could get a hub.)  Both have a 700 MHz ARM-based CPU, and 256 MB of RAM.  They are surprisingly capable graphics-wise (check out the link for more details), and they are also low power.  This is what interests me.

I posted before about possibly configuring my Web server to run at least partly on solar power.  On that post, someone commented on the possibility of using the Pi for this.  And so, I have a model B on order – this board uses about 3.5 watts, so that’s a start.  I would use an external USB drive for much of the filesystem, which would bring this up some, but it should still be less than my current setup which consists of a Mini-ITX board (about 1 GHz, with 256 MB RAM and a 120 GB hard drive).

I have a model B on order (should come in May), and my plan is to throw Debian on there and test this out.  My current server does a decent amount, but it doesn’t seem to get overtaxed.  I’d be looking to run Web (Apache; yes I know there are smaller servers that might work, but I’d like to try this), PHP, MySQL, Email (Postfix/Courier), and LDAP (Email backend).  This should be interesting, and if I make careful use of the onboard SD card I think there’s a shot that this could turn out well.

As for power, part of the inefficiencies of my current setup (roughly 30-4o watts at the plug) are due to the power supply.  With a much smaller supply I should be able to bring this down.  As I also mentioned in the other post, I would like to come up with some sort of power sharing solution, where the primary power source for the Pi is solar, with the mains as a fallback and a battery backup in case of a power failure.  The idea would be to keep a normal system battery charged, rather than taxing it by cycling it each night to keep the server running.  Maybe someday I’ll end up with so much solar that the ~10 watts the whole setup should draw will be a drop in the bucket 24 hours a day (10 * 24 = 240 watt-hours/day), but for now I would take this approach.  (Also, a backup battery is good for other things, and I probably won’t care much about my Web server compared to, say, charging the cell phone or pumping out the basement.)

If the Pi isn’t up to this, I’ll probably try it with a media center-type application, and maybe look into a Sheevaplug for the server.  (It has USB also, so I could literally almost drop it in place.)  My server does get its fair share of hits, between this site, the Fever Dreams mirror, and when I host images on message boards like Fark.  But, I think that a small machine should be fine.

DIY

If you’ve flipped through my previous posts here, you’ve probably seen that I am a bit of a renewable energy buff.  I like messing with solar power, for a variety of reasons.  I like the idea of not blatantly stabbing the environment and contributing to global climate change*, but I also like the idea of making your own power and being independent – electricity is something most people in this country are addicted to without realizing it.  There’s the idea of a quiet, easy source of portable power for fun and for emergencies, and then there’s just the fact that it’s cool.

(*Note: Please don’t start a holy war in the comments over the climate change thing.  There are plenty of places on the Internet you can go to debate/argue/flame for and against this, and so it does not need to happen here.)

Now, some time ago I came upon a magazine called Home Power – I think I may have been in middle school.  This magazine is a journal dedicated to small scale renewable energy, mostly residential.  Its founders purchased land off the grid in the 70s, and turned to solar as a way to not have to run a lawn mower engine to power the car tail light bulbs they used for light.  Because the small-scale renewable energy (RE) industry (responsible for the sale and production of photovoltaic panels, wind generators, control electronics, etc.) was in its infancy when they started publishing the magazine (late 80s), a lot of the articles focused on DIY.  Sure, small operations started creeping up where people offered installation and consultation for RE, but nothing like what you can find now.  A fair amount of progress was made by people playing around with the equipment on their own, sometimes even building their own.  And the Home Power articles often reflected this.

I thought this period in the magazine’s history was awesome.  I loved learning about the various problems these early pioneers had, and how they went about solving them.  I liked seeing what some people did with small systems, and the big systems others built.  It was awesome to see these people working toward solutions to some of the problems faced in the world (and which we still face).

Sometime in the early 2000s the magazine’s tone changed, however.  It was focusing less on the DIY aspect, and more on the ‘turn-key’ aspect – more and more of the systems showcased were belonging to people who didn’t fully understand the technology nor have the desire to.  Rather, due to factors such the cost (and reliability) of electricity in their area, environmental benefits, and maybe the presence of tax incentives, they paid a professional to design and install a system on their homes.  (Note that the last factor I mentioned may also provoke flames; see my climate change note above.)  Not much of a DIY aspect is present anymore.  In fact, it seems that quite a few articles in recent issues are not written by the system owners themselves, but by the system installers/designers, or even third parties.

Now, the truth is that I don’t have anything against people who simply want to make use of RE and don’t want to worry about designing and wiring their system, hoisting panels onto their roof, etc.  Honestly, it would be hypocritical of me.  I mean, I’m a Linux user, and even use Gentoo on my desktop.  And yet I also love Ubuntu for the fact that it presents GNU/Linux as an alternative for normal computer users who don’t care about recompiling their kernel.  (I’m actually typing this on an Ubuntu laptop right now.)  I guess I just miss the old format of the magazine, the one I kind of, well, grew up with.

Now, Home Power is still a good magazine; it’s not like you won’t learn about renewable energy from reading it.  In fact, it’s usually pretty descriptive even if it doesn’t discuss all sorts of homebrew solutions.  You’ll learn about solar power, and if you don’t get as in depth as you’d like you’ll have a good jump-off point for learning more.  They’ll respond to your letters if you have questions, too.  And, their magazine is just well-produced: it’s easy to read, no advertisements in the middle of articles, etc.

What I do encourage you to do, however, is go the extra step.  Yes, you don’t need to be an electrical engineer to use renewable energy, or do anything with electricity.  But there is value in going the extra step and being aware of what is going on with your renewable energy system, or anything.  And guess what: most of the information is out there.  If you’re curious, just go Google-crazy.  Buy some parts or system components, and experiment.  You never know what you might learn.

Fun with Solar Power

I normally charge an 18 AH sealed lead-acid battery to run small things like lights, and to charge my cell phone, radio, etc.  Well a couple months ago this battery died.  It was old, and sulfation had set in. I decided to upgrade to an AGM battery (the old one was a gel cell), and picked out the 49 AH version.  Since I am away at school most of the time, and don’t have the space to take the battery and set up a solar panel I had to wait until this week to go and start solar charging it.  So, here is my temporary setup:

This is just temporary.  I eventually want to get the panel mounted somewhere, and the battery inside.  But this is great for the time being.  The battery does well in cold temperatures (I’ll bring it in at night, of course), and should be able to hold enough that I can rely on the system a little more heavily once it’s more permanent.  This is just one 32 watt panel too, with the other one added it will be even better.

Small Scale Solar, and Other News

Well, for those of you in the Rochester area I will be talking a bit about a small solar power system I put together this Saturday at BarCamp.  This is my first time there, and I wanted to do something a little different than the other things that were on the list.  First, though, I have to make up a presentation, which will probably mostly happen tomorrow after my test.

But I have been thinking about it, and so I guess I’ll post a little preview here.  My system is small, utilizing a 10 watt solar panel.  Energy production, obviously, depends on how much the panel is in the sun; since it is not a permanent system, I don’t really have a fixed answer to that other than I’ll take it outside for an hour while we go to play frisbee.  The system is just the panel, a batter, and a charge control.  I use it to run some lights, charge my cell phone and radio, and my laptop.  I guess you could add an inverter too, but I find that most things I want to run I can do directly off of 12 volts (or through a DC-DC boost converter in the case of the laptop, which likes 16 volts to charge the battery.)

This system could be nice to take camping, or to an event of some sort.  While it might not anihiliate your electric bill or make you an ecoviking, it can be useful during power failures and emergencies.  And of course it’s a great learning tool; if nothing else it makes you aware of the fact that electricity has to be produced some how.  (After all, they don’t just pump it out of a hole in the ground, amiright?  At least, never that directly.)  We’re so used to electricity being that cheap stuff that comes out of the wall to power our digital lives, and kill us if we fuck around with it too much.  Well, there is something neat about making your own power.  So come on down to learn more.

Now for some other news.  It is actually starting to warm up a bit here.  The temp has been in the 50s quite a bit, even the 60s sometimes.  That’s a ncie temp, IMHO.  Sun’s out more too.

It was warm in our apartment too.  Warm and steamy, actually.  I went home for Easter, and came back Sunday night to find that the bathtub faucet was leaking, providing a steady stream of hot water for a decent chunk of the weekend.  My roommates had put in a maintenance request, and they finally fixed it on Monday.  It was actually pretty neat, aside from the gigantic waste of water and gas.  Our entire apartment was warm and humid, like a tropical paradise.  The sound of water was also kind of nice, though it was kind of lucky that I couldn’t hear it from my bedroom.

So that’s that.

Solar Powered Web Server

As you have probably noted from past entries I like to run my own servers.  I’m not running a big enterprise here, so they don’t have to be extremely reliable (though they have been very reliable).  Mostly, I like the control that I have, and the flexibility.

But I find myself running into a few brick walls here.  Mainly, electricity.  Now, it’s relatively cheap, particularly if I run a server at school where I don’t pay for electricity.  But, there’s also the wastefulness factor.  Global climate change or not, I’m not a fan of the idea of wasting energy.  Or at least grid produced energy that could result in carbon emissions.

Alright, if I really wanted to reduce my footprint I suppose I could walk a lot more instead of drive, maybe get a more efficient car, you get the idea.  But there are a lot of servers running out there, and someday it would be nice to be able to keep them all going with an alternative source of power.  Or maybe keep them going out in a remote location, or during a prolonged blackout.

Hence, my idea for a solar powered Web server project.  I have some of the parts for this project already, so but I’d still need to make a few more purchases.  The big thing is design, and here are my thoughts: If I can get some kind of embedded, single-board computer that draws say 3 watts at most and runs 24/7, that is 72 watt-hours per day.  (Just in case anyone is unsure, to get watt-hours you multiply watts by hours.  So 3 watts for 24 hours is 72 watt-hours.)  I will bump that figure up to say 90 watt-hours a day, just to compensate for losses in the battery.  After all, we do want to be able to serve Web pages at night, right?  So 90 watt-hours per day is not too bad.  Supposing that, in sunny Buffalo, NY we get an average of 3.5 sun hours per day, you would need about 25 watts of solar.

My solar arsenal right now consists of one 32 watt panel mounted on the side of my house, plus another 32 watt I have not yet installed, as well as a 21 watt flexible panel and a couple smaller ones.  (There’s also a big 100 watt panel in the garage, but that’s a different story for another day.)  So I have more than enough to make this work in terms of producing power; in theory one 32 watt panel should be enough, but having a second one in case of shade or low light from clouds would be good.

Now, we want some battery backup as well, as I mentioned before.  To do this we probably want to be able to run the server for say two days without sun.  (This isn’t mission critical.)  So, 90 watt-hours at 12 volts is 7 amp hours (90/12), so for two days that’s 14 amp hours.  Not too unreasonable; I have a 18 amp hour gel cell battery that should be able to handle that, without drawing it all the way down (which is bad for the battery).  Although I may consider getting a bigger battery.

Now, this will be a simple server, probably not something I’d install the standard LAMP stack on.  My main thought for this would be that it would also log data from the system via shunts and some analog-to-digital converters, and then present the data in a nice looking Web page.  Maybe if I felt like it some day I could even add some AJAX stuff to it, but whatever.

So this would really be proof of concept.  It would also be great for backup power; if there was a bad power failure I could of course turn the server off and use the power for other things, like charging cell phones and running lights and a ham radio.  So it would be a good thing to have.  I will soon be looking around for a nice single board computer to use as the server, and then maybe a better battery and solar panel location.  With a little luck I will be able to pull something together.  Stay tuned.