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Old 01-11-2010, 01:31 PM   #11
rotor_wash
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Actually Harvey, my controller does have a unique way of increasing power from the panel. I have a specially built panel that includes one extra row of cells that in theory will allow the panel to generate over 21VDC. The matched controller takes the excess voltage and with a bit of loss to heat, increases the amperage to the battery bank. On a good day I will see just over 6 amps from the panel that is converted to 7.5 to the battery. At least that's what the LCD says.
Since you store your TM indoors, you might benefit from Bill's portable method. I see you have lots of experience with solar, but if I'm not there to monitor it, I have a good controller that will.
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Old 01-11-2010, 03:28 PM   #12
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Rotor Wash -

You're describing an MPPT controller! If I may ask, what did it cost you, and how many watts are your panels rated for?

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Old 01-11-2010, 03:32 PM   #13
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Quote:
Originally Posted by rotor_wash View Post
Actually Harvey, my controller does have a unique way of increasing power from the panel. I have a specially built panel that includes one extra row of cells that in theory will allow the panel to generate over 21VDC. The matched controller takes the excess voltage and with a bit of loss to heat, increases the amperage to the battery bank. On a good day I will see just over 6 amps from the panel that is converted to 7.5 to the battery. At least that's what the LCD says.
Since you store your TM indoors, you might benefit from Bill's portable method. I see you have lots of experience with solar, but if I'm not there to monitor it, I have a good controller that will.
I didn't mean for this to be a battle of the controllers. I realize that they have their place and there are good reason's for some to have them, especially if the array out-weighs the batteries. That's just simply not my case.

With my panels, my usage and my batteries, there is simply no need of a controller....for ME......I'd rather have the panels putting 100% of their available output into the batteries 100% of the time.

BTW....most any solar panel will put out 21VDC (open circuit) if you put the voltmeter on the leads to the panel while it isn't connected to a battery. As soon as you connect the leads to the battery, the voltage will drop to just a volt or 2 above the batteries current voltage. As the amperage reaches capacity in the battery and the battery voltage increases, the difference between the battery being disconnected from the array and the voltage with it connected, will become closer. In other words, if you attach a solar panel to a battery that is reading 12.0V, a large enough array may take the voltage reading up to 13.3 or 13.8 (approx 1.5V increase) almost immediately. However, if you attach that same array to a battery that reads 12.7V, you will still only see 13.8 to 14V, a difference of about .9V (at least at first). It's kinda like filling a tire with air with a small compressor. The higher the pressure in the tire, the less effective the compressor.

If you have a solar panel that "includes one extra row of cells that in theory will allow the panel to generate over 21VDC" that simply means that one row of cells is cut-off part of the time while charging. Again, the controller cannot increase panel output. It's simply impossible. The only thing that a controller can do is turn a panel (or in your case, a part of the panel) off and on. This may make the final stage of charge more effective but I doubt that I will be concerned about the final state of charge while camping because my batteries will be in an almost constant state of discharge.
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Old 01-11-2010, 04:41 PM   #14
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Wayne -

You need to read up on the theory of MPPT controllers. Most of what you have said above applies quite correctly to conventional (PWM or shunt) controllers, but MPPT controllers are a different breed. An MPPT controller will, in fact, give you more power into your batteries than a straight connection from panels to batteries. However, this feat of electronics isn't cheap.

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Old 01-11-2010, 06:30 PM   #15
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Wayne -

You need to read up on the theory of MPPT controllers. Most of what you have said above applies quite correctly to conventional (PWM or shunt) controllers, but MPPT controllers are a different breed. An MPPT controller will, in fact, give you more power into your batteries than a straight connection from panels to batteries. However, this feat of electronics isn't cheap.

Bill
Electronics is simple math. I don't need to explain that to you. Are you telling me that this guy is somehow able to defy the law of physics? A single photovoltaic cell produces a measured amount of current under differing Sun exposure. An array is just a bunch of cells soldered together. They don't respond to outside stimulus from a controller, other than to connect or disconnect the cells from the circuit or a variety of circuits. They don't accept vitamins or pep-pills. This sounds a little like "Snake-oil" to me.... Although they do respond to cleaning now & then....

I'm just not interested in controllers. Too many years with toooooo many very expensive gadgets (remember me....I'm the gadget guy). When I put an array on my house, it will go right into the grid. No controller needed there either, just a nice expensive inverter......
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Old 01-11-2010, 06:36 PM   #16
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Yup, things have moved out of the early days of solar. Although I don't have 20 years of experience with solar, I spent a year deployed during the Iraq war with a lot of time on my hands for research. So my information for my system was current as of 2003-2004. I chose a system that featured one extra row of cells from the usual 36 to 44. this allows the voltage to go from 175 to 21.5. That is not the open circuit, but normal output. The MPPT controller takes the excess (high voltage) input and with a small loss, inputs it to the battery as an increase in amperage. That would actually be more than the 100% you would get out of your 17.5 VDC system. So that makes it not only a battle of modern controllers, but panels as well.
Bill, the system is from http://www.amsolar.com/am100.html. Rocky Mtn Ray was an inspiration to my research, especially the mounting process. I wish he was still here to comment.
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Old 01-11-2010, 06:52 PM   #17
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MPPT controllers don't create electricity, but they do take a 130 watt panel that does not really deliver 130W to the battery due to match issues and adjusts the voltage and current to match the battery to allow more of the 130W output to get to the battery. If you want the gory details get out your calculator ( or slide rule for us old-timers) and see the link below.
http://www.windsun.com/ChargeControls/MPPT.htm
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Old 01-11-2010, 07:29 PM   #18
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I've got these neat new spark plugs that will give you 10% better gas mileage.....and an air filter that will give you 20% better mileage...a fuel additive that will give you another 10%......they can all prove this stuff too. Heck, if you buy enough of these things, you can have a vehicle that will theoretically produce gas as you drive....
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Old 01-11-2010, 09:45 PM   #19
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I have a rather unique parking situation for my TM. I park in an apartment complex garage along with 80 other people. I also manage the apt building.

My concern is not so much the tenants. My concern is vandals that sneak into the gated garage on occasion.
Sounds like you've decided on a plan, but you could hide a permanent install on the roof if you threw an ADCO cover over the TM. That would make them out of site and make your TM look like a pop-up, which probably is not very attractive to thieves.

Just a thought....

Dave
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Old 01-12-2010, 07:20 AM   #20
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Wayne

Haven't tried any of those miracle inventions, but I did buy a travel trailer that folds down to about the size of a pop-up and then upon arrival at the campsite uses a counter balanced system to easily open to a full sized travel trailer. Oh yea it can also be towed by something less than a large pickup.
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