Monday, October 27, 2008

DIY Jackeroo solar PV system via kmart

I have been stalking this solar panel for several months, and up to now every time that it was advertised in Kmart junk mail it sold out before I got there.

Specifications and my observations:
  • $100
  • panel folds up into a briefcase form factor
  • includes car cigarette lighter plug socket adapters, battery clamps, and regulator with 3 LED indicators for charging, high voltage and low voltage
  • battery not included
  • included spec sheet sez: Peak output power 13W / 17.5V
  • charges a 12V battery, like a car battery, with which you can do as you may
Results in full sun:
  • regulator load output: 14.6V with no battery attached
  • regulator load output: 14.5V with battery attached
  • regulator battery current: .2A to .3A it varies counter intuitively to the higher number when panel is partly occluded by shadow
  • as above but with half the panel occluded: .38A
  • regulator load output: 14.0V with battery attached and half the panel occluded.
  • voltage from panel with no load: 21.9V
  • voltage from panel with no load: 21.3V with half the panel occluded

Now the challenge is to cobble a lifestyle solution to make use of the 12 volt battery power for the following devices:
  • AA batteries and charging them (for camera and shaver)
  • eeepc laptop, using 9.6V (also todo: try AA x 6 in series as an external pack)
  • LED desk light (IKEA JANSJĂ–) using 2.5V to 3.5V
  • ADSL router, using 12V
What remains to be seen is how much usable power will be harnessed on an average day, especially in terms of powering the above devices and any shortfall or surplus.

[Revision 20081029 : A peek inside the regulator module]

[Revision 20081115 : Regardless of one's view of power couplings and what ought to be, the trick is plain and simple: an inverter. Today I purchased an $79 300W 12VDC to 240VAC inverter at DSE, and I no longer care about regulators and car adapter, or whatifs. Sure, life is full of disappointments and compromises, including some inefficiency and compromised portability, but the electrons come from the sky so fckit. Mission accomplished.]

(the pictured battery was eventually retired after being found to behave defectively with seemingly very poor charge retention - it was replaced with a generic car battery which was also lying around in the garage)

[Revision 20081201 : Yesterday I had put my common sense aside for 24 hours and tried a pseudo hobo lifestyle, in my back yard and veranda. Tactics included: harvesting gray water to pour onto the yard by unscrewing the u bend from the outdoor sink and putting a bucket under to be emptied manually when; using only the electricity that my panel generates to run my laptop and LED light; using only USB 3g internet, so no ADSL, to live within my available electricity budget and kinda off grid; did not bathe for the third day in a row, as weekends do not really matter; used up my food with a few remaining garden greens; slept under a mosquito net. Result: enough! I need to double my solar panels to only barely have enough electricity to operate my laptop continuously and in full sun, because as it is only gives me maybe 3 to 4 hours of operation per day, though a full recharge cycle was not tried because of temperamental cloudy weather the day before. Ideally I would need a lot more generating capacity than my existing apx 10W. And then there were inefficiencies introduced by the inverter to go from 12V to 240V and a power supply back down again rather than feed directly into my laptop; waste does not help when it is so tight. And a 30 degree day of heat does not help either. This experiment is finished. The single solar panel is just not enough to stay in cyberspace, which is normally a modest expectation nowadays. The bottom line is that I need more power. For now I am committed to waiting for the price and performance improvements of another technology cycle before thinking about getting more hardware of any kind until (well maybe a 12V AA battery charger or a 32GB USB stick if I get tempted {by 5 months later both of these items were fulfilled}). In the mean time I will continue to use up each day's battery charge for such things as the LED night light, charging other batteries or whatever until discharge is reached - am partially solar powered. {Also it was later found the the output from the panel changes between summer and winder cycles, and this experiment dates to about spring.}

-note2self- jrm7262 foresaw what I was going to think today (telepathic and precognisant) and got the results of what I was going to find out the hard way, that is, powering the eeepc with non proprietary batteries but instead with standard AA batteries will fail. If I can project into the past then thanks.]

[Revision 20081201 :: Purchased a second panel, doubling my generating capacity to a spec total of 26W. Also the second panel seems to yield about 10 per cent more. I expect that I will be able to get more operation from my laptop, router and lights, though still compromising using all of the above some of the time or some of the above all of the time.]

[Revision 20090119 :: Purchased a third panel. I am still short on capacity, but also have budget constraints; this costs money.]

[Revision 20090401 :: Purchased 3 more panels, to a total of 6.]

[Revision 20090414 :: Lately the sky has been cloudy often which is also very unhelpful. Also I am awaiting delivery of a car charger for my eeepc and a 5W 12V LED which should allow me to eliminate the inverter from normal operation (the inverter drains at .25A, equivalent to the Jansjo)]

[Revision 20090702 :: winter months, current readings per panel .5 + .4 + .4 + .4 + .27 + .27 = 2.24A . It looks like 2 panels degraded.]

[Revision 20100508 :: current layout facing the sun, 12V CREE LED and an old LED, and a netbook 12V power adapter (all 12V, definitely no inverter) -- This project, this working prototype, at this rate will never be fit for recommendation. However compromised this configuration is (the chosen parts, and how they are setup) I have no intention of scrapping it, because it works for me, the resources had been spent, and there is nothing on the Want list to take it's place.]

[Revision 20100511 9:30am :: autumn months, current readings per panel .37 + .22 + .22 + .33 + .28 + .33 (sum 1.75A) measured total current 1.56. And then I washed them with a hose and broom and measured total current 1.72  (I don't remember the last time did any maintenance). I regret not taking any measurements during the last summer, but it is a bit of a hassle with undoing the cables and plugs. ]

[Revision 20110207 :: got a deep cycle battery, 75Ah, I got it on sale for $127 at Adelong. The earlier car battery's charge capacity had been destroyed by deep cycling.]

  • making my own electricity since 20081027; my system consists of 6x 13W solar panels (via kmart, second generation I believe), deep cycle 12V battery, 12V 5W MR16 ww 56deg LED light or drop in replacement (via ebay), 12V netbook PSU (via ebay); but i cheat at also take mains when it suits me  [20110531 this experiment is on suspended to do with domicile change]

[Revision 20120217 :: uninstall -- This system no longer first with my lifestyle.]
[Revision 20120309 :: free via friends with things,]
[Revision 20120420 :: via comment from Eric]
Anonymous has left a new comment on your post "Jackeroo solar generator via kmart":
Hi Bob
Nearly 2 years have passed and I thought to say g'day. I Now have 4 of these myself and have done some camping to photograph etc while living in the tent. I discovered that It would work my radio small laptop power 2 fluro lights and charge my phone and camera batteries no problem.
For a total of 54 watts I believe that I did well. I appreciate your blogs as it gave me an idea of what I would need - the only difference was that I hooked it all to a 5 in 1 power box which included an inverter but only 18AH of battery. no problem as I charged all AA batts and laptop through the days. On good days I would get 3.5 amps.
I wish to live off grid at home for 3 months and so have decided to buy 2x 100 watt panels and a larger batt for the excercise need more powa:) so I will sell these panels at 1/2 price to help with funding or look for others like the ones I have. Kmart no longer sell this type.
Thanks again for being my mentor :)

Hello Eric,

Thank you for taking the time to write kind words. 

Just like you, I too had gained a good amount of practical experience from this solar technology and off grid lifestyle adventure. I don't know about you, but during the high point I did actually think that this was going to go on indefinitely -- so I did not consider having to move home where it would not be practical to have these panels and system.

I wish you the best of luck in doing what you believe in, and to not get disheartened by short setbacks. We learn from what each other, as well as all the new things that we run into as technology improves.