
Building a Raspberry Pi based server powered 100% by solar energy - 666_howitzer
http://pi.qcontinuum.com/project.html
======
jrabone
45W sounds like overkill for an RPi - I live in Scotland (55.95N) and I have a
50W panel charging a 110Ah battery in my garden shed. The battery is used to
power a 1kW Invertek 250V inverter (150A fuses are impressive BTW) which I use
to run a lawnmower, power tools, soldering station and lights (not all at
once!).

The lawnmower is the biggest drain (900W) and is really pushing the envelope -
but in the summer I can cut 55 sq. metres of lawn once a week without any
charge problems. In the winter the grass doesn't grow :) but I can run the
other tools just fine. I was very surprised at just how well this system
worked, but then I did splash out on a high end 50W Kyocera panel when I
designed this. My only alternative would have been to bury an SWA cable across
common ground and somehow run it to my consumer unit in a 1st floor flat, so I
was prepared to spend £300 (as it was then) on the panel. They're a lot
cheaper now.

~~~
tocomment
So if I got a bigger panel and needed more power would you say to buy a second
battery? Would I just hook it up in parralel?

~~~
jrabone
If you need more power you have 2 options. You can add more batteries in
parallel and increase the size of the cables to take the higher current, or
you can go to a 24 volt system which means you can use the same cable. 24 volt
components are maybe harder to find though. My system is really intended for
short periods of peak power (say 30 minutes a week running the mower). It was
harder to find cheap inverters to handle more than 1kW at the time too.

------
fosap
I was investigating today into something similar.

The concusion of my research:

\- Model A uses a way less (about 33%) electricity, because it does not have a
lan controller. So it will be useless as a server, but for my application this
is the choice.

\- The RPi does work with 3.3 Volts, but then the USB does not work. Yet
again, for me good enough.

\- Undervolting (the core and ram) and downclocking do not make much sense. It
does save nearly nothing and make the board absurd slow.

\- The biggest powersink seems to be the GPU, but AFAIK it can't sleep.

\- The most inefficient component are the voltage regulators. Replacing them
with dc-dc converters was discussed, i have no experimental results. The
easies way is to convert the input to 3.3V without replaying and board
components.

\- Displays use very much power. But they can be turned of if not needed.

It seems the solar panel can be significantly smaller, but not for a
webserver.

------
platz
I think he could have halved the size of his solar kit and still not have had
to worry about power interruptions.

[http://pi.qcontinuum.com/cgi-
bin/rrd/rrdgraph.volts](http://pi.qcontinuum.com/cgi-bin/rrd/rrdgraph.volts)

~~~
idupree
Evidence shows the solar panels are important: He doubled the number of solar
panels in November after the initial panels weren't enough to power the RPi in
the winter.
[http://pi.qcontinuum.com/failure2.html](http://pi.qcontinuum.com/failure2.html)
(The graph also shows the voltage dip below 10V in Nov, probably representing
that failure, though it's hard to see the details in the "last year" graph.)

Maybe they could be pointed towards the sun more efficiently, or been a more
expensive & efficient model - but the story says why he chose his porch and
cheap solar panels.

~~~
astrodust
Adding some kind of rotation mechanism to the panel would increase efficiency,
and I'm sure the Pi or Arduino could handle this.

------
SpacemanSpiff
Excellent project, but the shading on the solar panels from the railings is
more than likely severely reducing the output of the panels at lower sun
angles. Even shading a single cell on a series connected panel effectively
reduces the output of ALL cells. Also having peak power tracking would
increase panel utilization. I really like the power monitoring using the
Arduino though.

------
stephengillie
This kind of research is nice to see. Too bad your setup needs a less-powerful
system (Arduino) and a more powerful system (RRD host) to operate the
charging.

What about using the RasPi's GPIO pins instead of the Arduino? And why
wouldn't an SD card be able to manage that many writes? What about a ram
drive?

------
garysweaver
Network traffic graph currently showing what it is like to be HN'd:

[http://pi.qcontinuum.com/cgi-
bin/rrd/rrdgraph.pi.main](http://pi.qcontinuum.com/cgi-
bin/rrd/rrdgraph.pi.main)

[http://pi.qcontinuum.com/rrd/pi-traffic-
day.png](http://pi.qcontinuum.com/rrd/pi-traffic-day.png)

[http://pi.qcontinuum.com/rrd/pi-traffic-
week.png](http://pi.qcontinuum.com/rrd/pi-traffic-week.png)

~~~
turshija
And the allmighty raspberry pi is surviving traffic like a baws :)

------
AaronBBrown
I've been wanting to hack on a few projects that involve small amounts of
electrical knowledge, but am not sure where to get the bare minimum
information to avoid killing myself or others. What is the best way to get
practical background knowledge about this type of electrical project?

------
csense
What are "the RRD tools"? What does RRD stand for?

Also, if you're worried about an application which does a lot of SD writes,
you could:

(1) Try it, see if the SD card holds up. If it does, great. If it doesn't,
well, SD cards are cheap, and you _did_ make a backup, right?

(2) Write to a RAM disk

(3) Write to a network drive

~~~
danellis
[http://oss.oetiker.ch/rrdtool/](http://oss.oetiker.ch/rrdtool/)

It's literally the first hit in Google. He probably doesn't explain it because
it's a fairly well-known tool.

------
brackin
Interesting. Looks similar to this project.
[http://www.engadget.com/2012/06/20/48-pandaboards-chained-
to...](http://www.engadget.com/2012/06/20/48-pandaboards-chained-together-in-
solar-powered-arm-cluster/)

------
MrDOS
> see how many years I could keep it running without a reboot

> I decided set up the panels on the deck facing west.

There seems to be some disparity between his goals and the stability of the
environment in which he's placed the equipment.

------
vinhboy
I wish there were more pictures and descriptions of how to hook up the battery
to the raspberry pi. That is the biggest unknown to me.

~~~
yesbabyyes
I don't know what the author used, but you should be able to build something
similar with these products/kits from Adafruit:

    
    
      - MintyBoost Kit http://www.adafruit.com/products/14
    
      - USB / DC / Solar Lithium Ion/Polymer charger http://www.adafruit.com/products/390
    
      - Li-Ion Batteries / Solar Panels http://www.adafruit.com/category/67

------
thejosh
142 days uptime is pretty cool!

