Author Topic: Small solar PV system  (Read 5091 times)

0 Members and 1 Guest are viewing this topic.

BT Humble

  • Sr. Member
  • ****
  • Posts: 475
Small solar PV system
« on: September 19, 2004, 04:32:07 PM »
Small PV system


I use this small photovoltaic system to run the 12V electrical loads in my caravan.  These consist of a pair of 8W fluorescent lights, a small "boom box" stereo, and a mobile phone charger.





A pair of cheap amorphous panels provide the power to the system.  These have a claimed output of 10 watts, but the maximum I have seen actually going into the battery is about 1.2 Amps.  They are connected to the battery by a length of cable intended for use with low-voltage garden lights.  This is pretty good stuff to use for such systems, since it's cheap, has reasonably heavy conductors and thick UV-resistant insulation.  I've put them on a pole mount, fixed at 45 degrees (which is a reasonable year-round compromise for my latitude, 45 Deg South).





Here's a view of the internals of the system (this fits under one of the seats.  Most caravans sold in Australia are pre-wired with 12VDC and 240VAC circuits).  On the left you can see a bundle of wires that connect to the tail lights (disconnected because this caravan isn't going to travel the road any more).  The black cable coming through the hole in the floor is the input from the solar panels, the white one disappearing through the floor goes to a cigarette lighter socket for the boom box.  The white cable heading off to the left feeds the 12V circuit for the van lights, the two black wires going to the right feed an additional light and a cigarette lighter socket on an extension lead that I use for my phone charger and suchlike.


The positive lead to the battery has a single 10A fuse, in order to keep things simple. Note that the way this is set up, if the fuse blows power will still be available for daytime loads on the system (well, up to the maximum output of the panels, anyway).





Here's a (rather blurry) view of the inside of the junction box.  I've used a couple of small brass bus bars (I bought a bucket of them for $2 from a scrap metal dealer) to keep the connections reasonably neat.  I'm using one side of a 35A bridge rectifier as a blocking diode, partly because it has easily connected spade lug terminals, but mostly because I had it on hand.


The system provides more than enough power to run two 8W fluoro lights for about 3 hours per night, the radio for a couple of hours per day, and to recharge my phone battery every couple of days.  I also use the 20W incandescent lights int he van when I need more light over the stove or sink, but that's usually only for a few minutes at a time.


BTH

 

« Last Edit: September 19, 2004, 04:32:07 PM by (unknown) »

dudevato

  • Jr. Member
  • **
  • Posts: 59
Re: Small solar PV system
« Reply #1 on: September 19, 2004, 04:44:00 PM »
BT, Pretty slick setup. Have you got some type of ventalation for the enclosed battery?. If you are not going to be moving the rig what about putting everything inside a small, insulated plywood box, below the floor?
« Last Edit: September 19, 2004, 04:44:00 PM by dudevato »

BT Humble

  • Sr. Member
  • ****
  • Posts: 475
Re: Small solar PV system
« Reply #2 on: September 19, 2004, 05:16:51 PM »


BT, Pretty slick setup. Have you got some type of ventalation for the enclosed battery?. If you are not going to be moving the rig what about putting everything inside a small, insulated plywood box, below the floor?


To be honest, I hadn't given it much thought!  It's a sealed battery, and at a 1A rate of charge it shouldn't be gassing much anyway.  Wwhen I got the van it had a pair of crocodile clips attached to the wiring, and based on the amount of corrosion on them I suspect it had a flooded cell battery with a fairly high rate of charge at some point...


BTH

« Last Edit: September 19, 2004, 05:16:51 PM by BT Humble »

LEXX

  • Full Member
  • ***
  • Posts: 129
Re: Small solar PV system
« Reply #3 on: September 19, 2004, 05:18:13 PM »
Sir Humble,  

totally off topic and completely nosey question here, what do you you with your land, it looks like you're out in the middle of nowhere?  Where is your computer, how do yuo get internet?

Just wonderin',

LEXX
« Last Edit: September 19, 2004, 05:18:13 PM by LEXX »

TomW

  • Super Hero Member Plus
  • *******
  • Posts: 5130
  • Country: us
Re: Small solar PV system
« Reply #4 on: September 19, 2004, 05:18:53 PM »
BT;


Pretty neat setup. I would also suggest a vented area for the battery although in a small system the amount of gassing would be minimal.


I like seeing this type of posting here. Dead on topic and a useful system others can look to for how it can be done. Easy to upgrade as components or funds become available, too.  


Thanks for sharing.


Cheers.


TomW

« Last Edit: September 19, 2004, 05:18:53 PM by TomW »

hiker

  • Hero Member
  • *****
  • Posts: 1661
  • BIG DOG
Re: Small solar PV system
« Reply #5 on: September 19, 2004, 05:21:02 PM »
hmmm-- well i see your lawn mower tucked under the front of your trailer..

but no lawn!! i known--just dig up an old auto alt and hook it to your lawn mower

engine..find some old auto batts and your set..[you think]



« Last Edit: September 19, 2004, 05:21:02 PM by hiker »
WILD in ALASKA

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: Small solar PV system
« Reply #6 on: September 19, 2004, 06:14:56 PM »
BT


Looks good.


How do you deal with overcharge? I don't see a regulator.

Or are the panels 'self regulating' (16v open circuit)?


Your charge current is right on track for the panels. Rated peak power is generaly about 17 volts.  17V X 1.2A = 20.4W.


G-

« Last Edit: September 19, 2004, 06:14:56 PM by ghurd »
www.ghurd.info<<<-----Information on my Controller

BT Humble

  • Sr. Member
  • ****
  • Posts: 475
Re: Small solar PV system
« Reply #7 on: September 19, 2004, 08:47:04 PM »


hmmm-- well i see your lawn mower tucked under the front of your trailer..

but no lawn!! i known--just dig up an old auto alt and hook it to your lawn mower

engine..find some old auto batts and your set..[you think]


I had to mow my driveway last year, the grass was getting a bit high and brown and I didn't want to start a bushfire.  6 passes did it, each of them 500m long (i.e.  About 2 miles). ;-)


I don't really need a generator here for lights, even during the winter it's quite rare to get more than 2 cloudy days in a row, and after a frosty morning in midwinter I'll still get 8 hours of sunlight.


BTH

« Last Edit: September 19, 2004, 08:47:04 PM by BT Humble »

BT Humble

  • Sr. Member
  • ****
  • Posts: 475
Re: Small solar PV system
« Reply #8 on: September 19, 2004, 08:50:05 PM »


How do you deal with overcharge? I don't see a regulator.

Or are the panels 'self regulating' (16v open circuit)?


Yes, they're self-regulating panels, and since I'm using the lights every day the battery seems to be fine.  I watched the battery voltage carefully for the first month or so, now I've gotten a bit blase about it because the battery was only a $5 special from the dump anyway. ;-)


BTH

« Last Edit: September 19, 2004, 08:50:05 PM by BT Humble »

BT Humble

  • Sr. Member
  • ****
  • Posts: 475
Re: Small solar PV system
« Reply #9 on: September 19, 2004, 08:53:55 PM »
Hmm, I only just noticed the warped view of my shed - that's what you get from a cheap digital camera I guess!



Seriously, I don't have a tame black hole next door, and my framing skills aren't that creative! ;-)


BTH

« Last Edit: September 19, 2004, 08:53:55 PM by BT Humble »

BT Humble

  • Sr. Member
  • ****
  • Posts: 475
Re: Small solar PV system
« Reply #10 on: September 19, 2004, 08:56:19 PM »
This is just the small secondary 12V system for lights for the van.  My primary system is 24V, with 560W of PV.  More than enough to drive the fridge, washing machine, power tools, etc. ;-)


http://www.geocities.com/za2bb/solar/


BTH

« Last Edit: September 19, 2004, 08:56:19 PM by BT Humble »

ghurd

  • Super Hero Member Plus
  • *******
  • Posts: 8059
Re: Small solar PV system
« Reply #11 on: September 19, 2004, 09:00:56 PM »
Cheap battery, cheap panels, cheap parts! It works. I love it.
« Last Edit: September 19, 2004, 09:00:56 PM by ghurd »
www.ghurd.info<<<-----Information on my Controller

BT Humble

  • Sr. Member
  • ****
  • Posts: 475
Re: Small solar PV system
« Reply #12 on: September 19, 2004, 09:02:25 PM »
I live near the village of Tarago, in New South Wales, Australia (Lat 35 03 S, Long 149 39 E).  Monday-Thursday I commute 90km (56Mi) to Canberra, where I'm writing this to you.


I don't have a landline phone at my van, but there's an underground telecom cable running across my land so I'll get one hooked up once I've built the house (currently slated to start around March).


Now I've shown you mine, where do YOU live? ;-)


BTH

« Last Edit: September 19, 2004, 09:02:25 PM by BT Humble »

Ungrounded Lightning Rod

  • SuperHero Member
  • ******
  • Posts: 2865
Re: Small solar PV system
« Reply #13 on: September 20, 2004, 04:11:24 PM »
On my little travel trailer I mounted a self-regulating panel on top of the air conditioner.  Ran the power wire in under the AC weather stripping, added a blocking diode, and hooked it into the ceiling light circuit so I wouldn't have to tear out the walls to run a wire to it.


It provides enough power to keep the two 85 amphour batteries up while the trailer is in storage if I turn off the propane leak detector (which is unnecessary when there's nobody around to hear it anyhow).


Panel is horizontal, to minimize the wind resistance and increase in the height of the trailer.  (It only adds an inch or so.)  I mounted it onto the AC cover mounting screws with a couple strips of aluminum.


Totally useless while camping, though.  In noonday sun, with the ceiling light fuse pulled, it only provides enough power to light ONE incandescent ceiling bulb.


I've got some surplus panels I'd been meaning to build into a suitcase-like device to set up beside the trailer and plug into the car pigtail to make the system self-powering for long camping trips.  (The batteries are good for a couple days if you need to run the furnace, but that's it.)  But after the wife got the boat we pretty much stopped camping, and after we started building the Nevada house we pretty much stopped boating, so I never got a Round TUIT.

« Last Edit: September 20, 2004, 04:11:24 PM by Ungrounded Lightning Rod »

LEXX

  • Full Member
  • ***
  • Posts: 129
Re: Small solar PV system
« Reply #14 on: September 21, 2004, 05:53:18 PM »
At the moment I live in Grande Prairie Alberta Canada, my wife and I live in a two bedroom apartment because we want a little chunk of land much like yours but for the time being the wife is in college to get her bachelor of nursing certificate and land around GP is expensive to the degree of unholy!  The worst part is all my projects seem to go to my father-in-law's farm because I would undoubtedly get kicked for erecting a windmill :-(

LEXX
« Last Edit: September 21, 2004, 05:53:18 PM by LEXX »

BT Humble

  • Sr. Member
  • ****
  • Posts: 475
Re: Small solar PV system
« Reply #15 on: September 22, 2004, 08:01:49 PM »
Hey, it could be worse!  For example, I could still be living in Canberra. ;-)


I expect it could probably be worse for you too.  I mean, at least your Mrs wants to go and live on a plot of land, and coming from a farm background she won't be all starry-eyed about it.


BTH

« Last Edit: September 22, 2004, 08:01:49 PM by BT Humble »