So what is a Solar Tracker, and do you need one?
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All too often I have been out bush to see campers set up with all the trappings set-up around them. This more and more now days includes a couple, or even four solar panels. But what I have seen at almost every campsite is the Solar Panels leaning against the side of a 4x4 or even a near by Gum tree, pointing everywhere but where it should be pointed; at the sun.
And the real tragedy is that many people buy expensive panels, and don't even know that they need to be in direct sun to be efficient. I recently spoke to chap who has even seen one happy camper with his solar panel lying flat on the ground and this camper couldn't understand why his fridge battery died during his first night out bush. So for the clueless, point your panels at the SUN, please.
So ok, why do you need a solar panel Tracker? And how does a Solar Tracker work?
Why you need a tracker is quiet easy to understand. Say, for example, you have just one 60watt panel to run your fridge that draws 1amp per hour of current from your batteries, and your solar panel produces 3.5amps.
Working on that assumption, your fridge needs a minimum 24 amps put into your battery each day.
Your 60 watt 3.5 amp solar panel is left sitting in the same spot all day, it may, if lucky, be working at just 20% of its full capacity. Many people don't realise how inefficient solar panels are; especially when left sitting in one position all day. So lets say your panel gets full direct sunlight for 3 hours per day. that's just 12.25 amps per day, leaving your battery 11.75 amp short on power. On this argument you would have a flat battery in just 3 days, if that long.
Now lets put your solar panel on a good solar Tracker. And assuming it is summer time. The Led Sensors I make will start following the sun from 1 hour after sunrise, around 6 to 6.30 am right through until around 6pm when its on full west Axis. so that's approximately 12 hours. Now, keep in mind your panel is not at its full potential until around 9.30 to 10am. so lets say it is getting full power by following the sun for just 8 hours. 8 Hours multiplied by 3.5amps = 28 amps for the day. Bingo!! your panel is not only running your fridge, its also keeping your battery fully charged.
Please note; The above is simply a sample calculation only and not to be taken as 100% accurate. Solar panels and 12volt fridges all produce, and drain, at a huge variation in amperage. You need to know exactly what current your fridge draws and how many amps your solar panel produces before you can do an exact Calculation. Also keep in mind there are other variables to take into account; IE; if its cloudy your panels will NOT produce as much power as normal, or, if camped in a heavily timbered area your panels will suffer due to the shadows from trees. Always try to set-up your solar panels in a sunny, cleared of shadows area. Remember the clearer the sky the more you get from a panel and a solar tracker.
Another thing many don't know about solar panels is this; a solar panel MUST be producing more than 12volts unloaded before it will start to charge a battery. If using a solar regulator the little green light can be telling you it's charging, when in fact it is not. On average your panel needs to produce around 13.8 volts to start charging current back into your batteries.
On that subject of current, please keep away from cheep so-called "12 volt trickle chargers from China you see advertised on Ebay etc. They are exactly that, a trickle charger and are totally useless for keep a fridge battery charged. You might get 50 to 100 milliamp from one, if lucky, which is not enough to charge anything bigger than a torch battery. For camping with any portable 12 volt fridge you will need a minimum of 85 amps. Always buy more power than you think you need, this helps on cloudy days. I personally recommend 85 to 120 watts for fridges, even when using a solar tracker.
OK, so how does a solar tracker work?
Solar Trackers are an ingenious invention, yet their idea is simple. As the sun passes by the two LED's on the Sensor box one led will produce more current than the other, this then tells the programmed micro chip inside the box to send current to the actuator, telling it to move to catch up to the sun, hence keeping your panel pointed at the sun all day.
The solar Tracker can be run from the batteries you are maintaining or from a totally dedicated battery. The current used by the solar tracker is so minimal its not worth worrying about. To give you an idea , the motor on the CampaTracka range of solar trackers are a 3amp motor under full load; however they never get to work under full load.
Now I realise many will say "hang on, 3 amps?" The trick is that it only actually used about a 10th of an amp per day. The reason is again due to variables. For example, the tracker only moves every 4 to 8 minutes, depended on weather conditions of course. And when it does move it moves for about 30 microseconds.. Blink and you have missed seeing it move. With two 60 watt solar panels on my own tracker, the actuator draws only .68amps when on a full incline east or west, but it only draws it for a few micro seconds.
A simple test gives the answer to its current use in one day. and its easy to figure out. Because the panels only go to east and back to west once per day, and it takes only around 40 seconds to go from full west axis to east again, ready for sunup the next day, this equals just 80 seconds of motor movement per day. And even if we say it draws 1 amp per hour, the current used is so minimal I won't bother doing the sums.
I use a small 7 ah battery on my tracker V3 and it will run the tracker for weeks before I need to charge it. I also use another 5ah battery to test run every tracker I build and I only charge it every 6 to 10 weeks. So the current drained by the track is so minimal it's not worth worrying about. And the gains of using a tracker should now be very clear to all.
Please note; this page is as yet incompleated and figures may be incorrect.
I will add more info to this page as time allows me to do so.
When time allows I will find the formula for working out what size panels you need for your fridge. This may be a week or so as I am simply too busy making trackers which are now backordered by around one to two weeks. If you want A campatracka portable tracker please contact me to arrange a deposit or full payment and for a delivery date. I work on a "first in best dressed" principle. In other words whom ever pays first is first to receive their tracker.
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