This instructable will tell you how I went about building a 12v Solar setup to run my Air Cooler during our hot Summer and a 12v 120 litre Fridge/Freezer during the cooler months.
It will include some of the things I got right and the things I got wrong while building my "Sun Suckers".
Please keep in mind that I am not qualified in this area and that my methods were based on a "research then trial and error" system.
Please use the ideas presented as a guide and improve on them wherever you can.
I won't be covering "in detail" panel building as such but will include helpful stuff (mostly discovered by the afore mentioned "trial and error' ) that wasn't covered in the many panel building Instructables and articles I read while doing my research.
Step 1: Learning. Think Beyond Today.
If you spend as much time as I did scouring the web for every bit of information available you'll probably get as confused as I did at first.
There's a lot of good info out there but there's a lot of rubbish too.
As a rule of thumb the greater the number of people say something, the more likely it is to be correct. Usually. But not always.
There are already some "Instructables" on panel building on this and other sites that contain credible and very useful information.
Very few of the articles etc. that I read, however, pointed out the life expectancy of the Solar Cells you'll be using versus the materials used in constructing the DIY panels.
The first Solar cells ever made still produce electricity and look likely to continue doing so for many years to come!
A piece of painted plywood used to mount your Cells on, on the other hand, will have a very limited lifespan under the hot conditions inside a panel.
Most articles I read are concerned with building panels "on the cheap" as I did.
I built more than 300 watts of panels, all on plywood.
I will eventually need to somehow remove the Cells from the plywood and rebuild the panels on something more substantial, not sure what ( or how ) yet....maybe aluminium or Tedlar? Not a job I'm looking forward to but all part of a fairly steep learning curve.
Think outside the square and make Google your friend. A search of "solar panel backing" returned 98000 results including this one.. http://www.treehugger.com/files/2008/08/cotton-castor-beans-combined-solar-panel-bio-backsheet.php
My advice......research thoroughly then do it once and do it right.
Step 2: Choose Your Materials Wisely.
This is the most critical step.
As mentioned earlier, the materials you choose to construct your panels with will determine it's lifespan.
Don't shortchange your Panels like I did mine
There are commercial products available for mounting Pre Tabbed Cells which include "Tedlar"(R) http://www2.dupont.com/Photovoltaics/en_US/products_services/backsheet/tedlarPVF.html .
#Edited 29th of May 2011#
I now sell sets of high quality, high output 3" x6" and 6" x6" Solar Cells on Ebay.
I also stock all necessary items for Tabbing and Stringing your cells.
I am doing this because of the poor quality of other sellers products.
My items can be seen here: http://shop.ebay.com.au/bigpat004/m.html?_trksid=p4340.l2562
Use 32 to 36 (32 is the minimum for a 12volt panel) of the Highest Amp rating Cells you can afford.
Even using the very best materials your panels will struggle to cost half the price of a commercial panel.
Step 3: Wots Watts?? Tabs?? Which Cells to Buy?? Soldering Iron?? Solder??
Watts are calculated by multiplying the voltage of the cell by its rated amperage. Simple.
Well not really.
The formula for say......a panel built using 35 0.55 volt, 3.6 amp cells would be this:
Voltage of each cell (0.55v) X rated Amperage of each cell (3.6a) X 35 cells = 69.3 Watts. A nice sized panel and well worth the effort.
Smaller amperage cells are obviously cheaper but involve the same amount of preparation, construction materials and soldering as bigger output cells do........you work it out (and buy the biggest you can afford).
Untabbed Cells or Tabbed Cells?
Factory "tabbed" cells will have the tabs attached to the front of the cells and should, in theory, save lots of soldering.
This is not always the case.
Factory tabbed cells are generally solder free. The tabs are "tinned" on to the cell rather than soldered.
Of the cells I used about 10% needed the tabs re-attached properly, not an easy job.
Based on my experience I would opt for untabbed Cells and put up with the extra work involved, happy with the knowledge that every tab is connected properly.
Keep in mind that you really must use Pre Tabbed Cells if using the Tedlar backing materials as the Cells sit flush against the Glass.
Keep in mind that the panel is only as good as its worst soldered connection. Make them all as good as you can.
That brings me to the Soldering Iron, the tool that will become your friend (sometimes not) and ally in your efforts to make the world a greener place.
My weapon of choice, after much research, was the Doss 48watt 929B Soldering Station found on eBay (Aus) for about $70 delivered.
It solders well when set near the top of the green range and desolders well at the bottom end of the red range.
Do lots of practice soldering (unless you're already very familiar with soldering) it will make a world of difference. Practice on hard to solder stuff like nickle wire or chromed metals.
Contact me if you want a few scrap cells to practice on.
Check out the instruction manual that came with your Iron....it'll give detailed instruction on how to care for the Tip of the Iron.....very important.
Step 4: Before You Solder.
The Cells need to be soldered together in what is called Series, that is, the positive side of each cell connected by tab wire to the negative side of its neighbour (see diagram)
To achieve this the (untabbed) Cells all need to be tabbed, that is to have flat Tab wire soldered to the front (negative) side and then to the back (positive) side.
Buy a roll of the thinnest Resin Cored Solder you can find.
Dick Smiths (Aus) sell a good 0.8mm solder at a reasonable price.
You may not find flat tinned Tab Wire at your local Electronics store so eBay (USA) could well be your best place to look. That's where I got mine.
It's a flat copper wire tinned on the outside and comes in several thicknesses. I found the thinnest one easier to solder to the Cells.
"A Resin Flux Pen".
This is a Must have.
Try your Electronics store. If they haven't got one they should be able to get you one.
If they can't a Google search will find you a supplier.
The Soldering Iron
Preheat your Soldering Iron to about 270 degrees C. and give it a wipe on the damp sponge that comes with it (a small natural sponge that needs to be just dampened with tap water).
Cut Your Tab Wire to Length.
This is a good time to calculate the number of (eg. 72 for a 36 cell panel) and the length of the tabs you'll need and to cut them to length (or a bit longer....just to be on the safe side).
The length will need to be almost twice the width of the cells to enable it to cover all of the Front Bus and to go across the Back Busses (there will be at least 2 directly behind each Front Bus).
A Small Fan.
You'll be doing a lot of soldering.
The fumes that come off the Resin Flux and the Solder as you're working may not be harmful but.......I'd rather not take the risk.
I mounted a small 12v fan (out of a PC) on my soldering board to take the fumes away from my face.
I made a foot operated switch for it and run it off a transformer.
Holding Your Solder.
You'll be holding your solder for long periods of time.
The Solder contains Lead.
To be on the safe side I run the solder through a thin (red) plastic tube. This acts as a Handle and stops contact with the solder while still allowing easy use.
Step 5: Soldering the Tab Wire to the Cells.
This is where all that Soldering practice will pay big dividends.
Depending on the cells you've bought and the type of panel you're building you may need to solder Tab wire to the Front, the Back or both.
Front busses take more work so I like to do them first. UnfortunatelyI don't have any pics of the process.
Ok....your Irons hot so lets go!
Apply a small amount of flux (with your Resin Flux Pen) along the length of each front Bus.
Starting at one end heat the bus and apply a small amount of solder as flat as you can along it's length.
Place the Tab Wire over the solder and hold it down at the end with your Iron.
Apply a small amount of solder to the Tab Wire where the Iron touches it. As the solder underneath melts move the iron along the Bus applying a little solder as you go.
The Tab should be attached all along the Bus for best results.
Very similar to Front Busses.
Apply a small amount of Resin Flux to the each Bus, heat them with your Iron for one or two seconds, apply a small amount of Solder and spread it as flat as you can with the Iron while it's still runny , place the Tab over the solder etc. as with the front busses.
Step 6: Choosing Your Construction Materials.
Parts of this step are pretty much a repeat of an earlier step.
I have done this to emphasize the importance of materials choice.
If you can afford it go for the Tedlar products and the best non reflective glass you can get your hands on and follow the instructions that come with the Tedlar materials.
The end product can be mounted on a timber or metal frame.
If you opt for the Tedlar (R) products you will only need to be building a waterproof housing or frame for your panel as the Cells (as I understand the process) are laminated to your glass. The instructions that come with the products will cover the process. Don't hesitate to contact your supplier or Dupont if they are inadequate.
Using Tedlar you have the potential of building "professional" grade panels.
If you use this Product please write an instructable on your experiences.
If your budget doesn't stretch that far simply pop "solar panel" in the instructables search bar and sort through the existing works till you find one that uses the materials you can afford.
Some things to keep in mind.
*To fail to prepare is to prepare to fail.....sounds corny but it's true....especially if you're using painted timber and/or plywood.
That was the big mistake I made with my first panel. I used "been sitting around the shed for years" paint, didn't use a timber sealer primer, used crappy undercoat and even worse topcoat.
After only 3 months the paint had deteriorated and the ply started to crack.
*Use the very best enamel paint you can afford and use multiple coats.
Every bit of protection you can give your timber will add years to the life of your panels.
*If you opt for Perspex rather than Glass for the front make it removable.
It will discolour over time and need replacing.
Mine is attached with 75mm wide Self Adhering Aluminium Flashing (from Bunnings). It sticks really well and is wide enough to seal the edges and sides of the panel.
When warm/hot this stuff is really sticky and a bit hard to handle. Whack it in the fridge (make room by taking a Beer out) for about as long as it takes to drink the aforementioned Beer. Just coincidence I promise.
*Perspex bends when it gets hot and it Will get hot when your panel is out there sucking sun.
I found it necessary to attach 3 or 4 1cm plastic stoppers (see picture "Stoppers") between cells on one panel and a Cork (see Pic "Cork on another to prevent the perspex touching, and possibly damaging, the cells.
*Perspex also reacts badly with the fumes from Clear Silicon so make sure any Silicon used inside the panel is totally dry before the perspex goes on.
That was my second big mistake. In my hurry to my first 70watt panel finished I attached the Perspex too soon resulting in damage to the inside surface of the perspex which reduced the performance of the Cells.
I have to replace it in the near future.
In our climate, inland Australia, the panels get extremely hot inside.
Plan really well for good airflow (I put vents at top and bottom of the back of the panel but more would be better see picture ) , even consider small 12volt fans to pull more air through (they could be powered by the panel itself).
The cooler the Cells are kept the higher the output
Step 7: Building Your Panels.
My blog at http://diysolarpanels.blogspot.com/ is pretty much a description of my Panel Building experiences from my first few Panels.
In it I give details on joining cells correctly and constructing panels on a tight budget.
Step 8: After the Panels Are Built.
Now that you have built and tested your panel/s you need to harness all that Free electricity you're suddenly producing.
The Controller is the brains of the system.
Your panels charge your batteries through it and it supplies that power to your appliances.
It controls the amount of charge that goes to your Battery Bank and protects your batteries from damage.
In my case I use 12v controllers and appliances but 12v panels can also be used to make a 24v, 36v, or 48v system.
Choose one of a voltage that suits your application.
You also need to calculate the total amp output from your panels and buy a controller rated to handle at least that amperage (keep in mind that you may wish to add panels to your system in the future).
The Battery Bank/s
I started with 1 x 12volt 85amp hour Deep Cycle battery and added another 5 from Alco Batteries in Wagga Wagga as funds allowed. They are joined in Parallel (positive to positive).
This gave me a 510amp hour bank which is being charged by 210 watts of panels.
eBay struck again and I found myself the new owner of 6 x 2volt 225amp hour batteries. These are joined in Series (positive to negative) to give 12v.
They're ex telecom style deep cycle batteries out of a communications system UPS (emergency power supply).
These batteries are a great starting point as they're cheap (or should be) and still have a few years of life in them if looked after properly.
Mine had some Sulphation on the plates but that disappeared after a few days of charging from my panels.
Sulphation occurs when the batteries are left flat for a long period of time and is frequently reversible but not always.
To charge this set of Batteries I built a 90watt Panel and bought another controller and now have an emergency backup power supply for the 12volt appliances.
You might think that only being 12v your system need only use thin wire (ie: speaker wire).
The thicker the better.
Because 12v doesn't have much "push" to get it along the wires you need to spread the effort as much as you can when any distance over 1 meter or so is involved.
If you don't the resistance will cause serious voltage drop and will cause the wires to heat up.
Several house fires have been caused by wires overheating to the extent of short circuiting.
Once again it's a case of doing your research then, keeping safety in mind, buying the best you can afford.
I used "Molex" connectors (recycled from old PC's) and 2.5mm wire to join my panels to the system.
The appliances connect to the controller Load output through very very thick car "boomf boomf" subwoofer cable (I had to solder a small length of 2.5mm wire to the end so it could attach to the controller)..
Step 9: The LED Solar Tracker.
Your Panels will produce much (30 to 60%) more electricity when they're kept pointing directly at the Sun as opposed to sitting in the one position all the time.
To achieve this you need to buy or build a Solar Tracker and mount your panels on it.
You have 2 choices here....you can opt for a "Dual Axis" tracker that will follow the Sun from East to West then, when the Sun goes down, return to face East again for Sunrise and will also adjust the North South (in the Southern Hemisphere) angle to cater for Seasonal change.
Choice 2 is to do as I did and build a Single Axis tracker that I can alter the North South angle of manually.
The LED Solar Sensor Unit uses 2 Red LEDs to detect the position of the Sun.
The innovation here is not mine.
I bought the Actuator and the Sensor unit from Dave at http://campatracka.com/index.html .
Dave's a really helpful bloke who's health doesn't always let him build his units as fast as he would like. He's a fair dinkum Aussie who'll give it his best shot so support him.
When ordering please bear this in mind and be Patient.....the units are well worth any wait.
To test run the Actuator and Sensor units before committing myself to too much spending I built my Prototype tracker using my DIY 90 watt Panel.
When I was satisfied that it was a good investment, which didn't take long, I built the bigger unit to house the 3 X 70 watt and the 90 watt panels.
Step 10: Building My Demountable Tracker.
This is a very basic "no frills" Dodgy brothers style of tracker......but it works.
Because I'm old I'll be giving most measurements in Imperial measure. A good converter can be found herehttp://www.helpwithdiy.com/metric_conversion_calculator.html
As I mentioned earlier I bought my Actuator and Sensor unit from Dave at http://campatracka.com/index.html
The Actuator is an 18 inch, 90 pound thrust 12v electric Ram.
The Sensor Unit is an East-West unit with automatic darkness return to East.
Building the Demountable Tracker.
As I'm in rented accommodation I had to build the tracker to be demountable.
My methods and materials will differ to an extent when I rebuild it as a permanent rooftop unit (when we finish renovating the house we own). The Star Picket Posts, for instance, will be replaced by an angle Iron Frame.
1 X 10ft Farm Gate..
1 x 12ft length of 1" Galvanized Pipe.
1 x 10ft length of 2" Gal Pipe.
2 x 6ft Star Picket fence posts These can be replaced by lengths of 2" heavy gal pipe if desired.
1 x Right angle Shelf Bracket.
1 x Packet of 1/4 inch x 2 inch gal bolts, nuts and washers.
1 x Packet of 1/4 inch washers.
1 x 3/16th inch? (depends on the hole in your actuator ram) x 2 inch bolt with 2 extra nuts and washers. This bolt is for the end of your actuator ram so check the size first.
Heavy Poly pipe or similar for spacers.
Various bits and pieces for attaching the bottom of the Actuator to the post.
The 2'" Gal pipe is welded to the centre of the "back" of the Gate. (the side the mesh is Not welded to).
I have not included close up photo's of my welding lest you be overcome with mirth..
To make the unit not seasonally adjustable as I did the 2 Picket Posts are hammered vertically into the ground about 10ft 6" apart on a North South alignment.
The 1" pipe and posts are drilled, the 1' pipe slid into the 2" pipe (if necessary a Spacer slid on to prevent the gate touching the post) and the 1" pipe is bolted to the Picket Posts.
To make the unit seasonally adjustable the Equator end of the unit needs to be able to be lifted up and down to keep the panels pointing as directly at the sun as possible all year.
To achieve this you will need to put that end post in the ground on an angle so that the 1" pipe can be lowered and still be bolted to the post.
The following is Theory only and has not been tested.
Hammer the non equator end post vertically into the ground. A foot or so should be far enough.
Drill a hole at least 1/4" dia in one end of the 1" pipe about 3" from the end.
Drill a 1/4" hole through the stationary end post 2" from the top.
You can find the angle your adjustable end post needs by bolting the 1" pipe loosely at the other end and resting the unattached end on the ground.
Put the end of your post on the ground a few inches along the 1" pipe and mark the pipe.
Correction....I woke up with a start at about 3 this morning (yep ...weird I know) with the realization that the bottom hole on the post will need to be approximately half the width of the gate up from the ground. If it's not then the gate won't have enough room to do it's East West thing.....
Have a helper lift the 1" pipe halfway up the post and mark the pipe again then lift it to the horizontal position and line the top end of the post up with the mark you made.
Hammer the post into the ground keeping it lined up with that mark.
Drill 2 holes, one at each mark through the adjustable end of the 1" pipe. Make sure they line up with each other.
Drill the same size hole through your post 2 inches from the top.
Drill 2 holes down the length of the angled post, one near the centre and one near the ground.
Find the exact positions by lining the up with the holes in your 1" pipe.
These will be your seasonal adjustments.
Cut 2 Spacers. Refer to Diagram2. This spacer will stop your gate from touching the post.
The 1" pipe is slid into the 2" pipe, the spacer put in place, the gate is lifted up and the 1" pipe bolted to the posts.
Attaching the Actuator to the gate is done via the Bookshelf bracket.
The bracket on my unit attaches to the end of the gate about 8" from the side. See Diagram 3.
The "leg" of the Bookshelf Bracket not attached to the gate is twisted at right angles to allow it to be attached to the Ram.
The bottom of the Actuator attaches to the Post about 32" down from the Gate.
These distances are another Trial and Error thing. Experiment till you find the positions that allow the Actuator to move the gate from a morning position facing Sunrise to an Evening position facing Sunset.
You Must use a method of attachment that allows the actuator to move at each end.
At the end of the Ram I achieved this by using 2 nuts tightened against each other either side of the Bookshelf bracket, See Diagram 4.
A lot of head scratching and shed searching went into the bottom attachment.
I was lucky enough to have a bolt like part that suited the job at hand. See Diagram 5.
I don't know what it's called or where to buy one but I do believe it's an auto part of some sort. The head part is about 1" dia and the bolt is 5/16"dia and about 2" long. The hole needs to be able to accommodate a 1/4" bolt at least.
If you've made it this far you'll work it out.
Maybe Dave at http://campatracka.com/ can suggest something.
The Sensor Unit.
My unit did not come in a weatherproof casing. To overcome this I Temporarily I mounted it to the Gate in a "Tupperware" type clear plastic container.
I drilled and screwed the lid to the gate at a right angle and drilled another hole in the lid for the units mounting screw.
Two holes are cut in the bottom of the container for the wires and the container simply attaches to its lid.
I intend building a box out of Perspex to house the Sensor unit permanently.
My Tracker unit is Powered by an old car battery which I trickle charge with a small Solar Panel.
A small 12v deep cycle battery such as those found in kids Electric Scooters would be perfect and should only cost $20 or so new.
Alternatively you can power from your controller.
Once the unit was finished I braced the posts with Wire "Guys" using some large Tent Pegs and some recycled fencing wire. See Diagram 6
Step 11: Update.
Tuesday 16th June.
A lovely sunny winters day had me outside making my tracker Seasonally adjustable.
I didn't do it quite as I thought I would.
I simplified things a bit.
I utilized the holes already in the Picket Post and opted for a 2 position setup.
Up near the top of the post for Summer and about 2/3rds of the way down the post for Winter.
It's not perfect but it will increase the total daily output of my panels during Winter by enough to make it well worth the effort.
The rope in the pic was a "safety harness" used while I was doing the constructing and has since been removed..
Step 12: Some Benefits.
Producing even a small part of your households electricity with panels you have made yourself has some flow-on effects.
In our house the Electricity Bill dropped much more than the amount my panels produce.
The very process of building the panels and setup, by default, involved the whole family in one way or another.
A net result of this was an increased awareness in all family members of their personal electricity use.
The changes were not earth shattering...just simple stuff like changing to efficient light globes, turning lights out when leaving rooms, shorter showers (sometimes :~( ), turning the TV etc. off at the wall, turning computers off at night.
Add that to the savings given by changing the Air Conditioner to Solar and you start to make a difference.
For the past 2 years each of our electricity bills has been as much as 25% lower than the corresponding bill from the year before.
We actually get a "Thank You" from our Supplier, Country Energy, and the bill details the Carbon Emission Savings etc.
Don't be fooled by ads, trying to sell you Solar Panel building kits etc., that claim you'll save 95% off your power bill by building a panel or 2. Simply not true.
!000watts of fixed, grid tied, Solar panels will directly save about 25% of the average Aussie familys electricity costs. You can double (or better) this by opting for a Tracker system.
Extrapolating on that equation a 2000 watt grid tied Tracking setup should cover most of a households electricity costs and, if you change electric hot water to Solar Hot Water, you might even make money from the power your panels produce.
Step 13: Grid Tied or Batteries?
A Grid Tied system, as most commercial systems are, feeds the electricity you produce into the mains through an inverter that needs to be installed by a licensed electrician.
You receive credits from your supplier for the amount of electricity you produce. This electricity is then on-sold to consumers as Green electricity at a premium.
This setup has advantages and disadvantages.
One advantage being you don't have to buy and upkeep a Battery Bank,
One disadvantage is that if the mains go down you're down too.
A hybrid system is possible but will also need professional installation.
This is a Battery system that diverts the power to the grid when the batteries are fully charged and appliances are not running.
Step 14: Insurance.
Insurance Company's may require an inspection of any 12 volt wiring installed DIY. It would pay to ask.
Add your Panels, Batteries etc to your household content Insurance cover.
Step 15: That's About It.
Now all you have to do is get out there and Do It.
I'll be updating this instructable as new ideas emerge and suggestions come in.
I hope you've enjoyed the read and have gained a little from it.
I hope I've inspired you to give it a go.
All the Best.