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Correct panel ('s ) for my application
http://solar-guppy.com/forum/viewtopic.php?f=3&t=692		 Page 2 of 3
Author:  mike90045 [ Wed Sep 17, 2008 10:41 am GMT EthGMT ]
Post subject:  Re: Correct panel ('s ) for my application
Solar PV panels produce power along a curve
(page 10, of this .PDF http://apps1.eere.energy.gov/education/ ... output.pdf ).
With no current draw, they produce max Volts. Into a short they produce max Amps. Somewhere in between, is the MAX POWER, where both volts and amps are high. (but not at their Max.) Manufacturers easily determine this "sweet spot". When you get your new panel home, it's nearly always going to be connected to a battery with a lower voltage, than the panels Max Power voltage (19V?) This means the panel will never produce max power. The magic in a MPPT controller, sweeps the voltage/load on a panel, till it finds the Max Power voltage, and then with a 95% efficient converter, down converts it to your battery charging voltage, and increases the amps as it does so [ Watts in = Watts out, - 5% ]. Sort of like an Automatic Transmission, but for PV, not your car.

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Author:  niel [ Wed Sep 17, 2008 7:12 pm GMT EthGMT ]
Post subject:  Re: Correct panel ('s ) for my application
sorry about that as i shouldn't have used the open circuit voltage, but rather the vmp. the principals are the same though. the current will be smaller than i originally figured in downconverting as the ratio of input to output voltage will be smaller.
Author:  Different Drummer [ Thu Sep 18, 2008 7:42 pm GMT EthGMT ]
Post subject:  Re: Correct panel ('s ) for my application
Thanks Niel,
I will plug in the correct values for some of the panels that I can use.
This will help me mke a deesion.
If I choose some panels where the final amperage number exceeds 15 ( Max. output of the controller ), I would assume that this would be OK as the Panels will not often be operating under ideal conditions.

niel wrote:
sorry about that as i shouldn't have used the open circuit voltage, but rather the vmp. the principals are the same though. the current will be smaller than i originally figured in downconverting as the ratio of input to output voltage will be smaller.
Author:  niel [ Fri Sep 19, 2008 2:49 am GMT EthGMT ]
Post subject:  Re: Correct panel ('s ) for my application
minor excursions at or beyond the 15a won't hurt anything as the cc will hold it to 15a, although it is wastefull going beyond the 15a. do note that the max wattage for the sunsaver mppt is 200w for 12v battery systems and 400w for 24v battery systems so i'd say the 2 am100s are a good match in theory.
http://www.morningstarcorp.com/en/SunSaverMPPT
get the battery temperature sensor if you get this cc.
Author:  Different Drummer [ Fri Sep 19, 2008 10:46 am GMT EthGMT ]
Post subject:  Re: Correct panel ('s ) for my application
Alresdy have the CC and RTS in my hot little hands.
Know anything about "Power Up " solar panels? I noticed that the warranty does not match others in the industry.

niel wrote:
minor excursions at or beyond the 15a won't hurt anything as the
http://www.morningstarcorp.com/en/SunSaverMPPT
get the battery temperature sensor if you get this cc.
Author:  niel [ Sat Sep 20, 2008 8:10 am GMT EthGMT ]
Post subject:  Re: Correct panel ('s ) for my application
i don't know too much about them, but from what i see why bother with half of the warranty with ul listing as being pending (maybe forever pending) for the same money that will get you a ul listed pv and a better warranty?
Author:  Different Drummer [ Mon Sep 22, 2008 8:27 pm GMT EndGMT ]
Post subject:  Re: Correct panel ('s ) for my application
Your correct. No brainer.
I spoke with Morningstar today to clear up a couple of questions. Person I spoke with was very pleasant, patient and helpful.
Gues I just need to get all the components in one place for install.
Any suggestions for type and source for wire. Panel to controler and controler to Batt. Something called "Ships cable" was suggested to me. I havn't a clue as to what that is, and cannot find anything when doing a search.


niel wrote:
i don't know too much about them, but from what i see why bother with half of the warranty with ul listing as being pending (maybe forever pending) for the same money that will get you a ul listed pv and a better warranty?
Author:  niel [ Mon Sep 22, 2008 11:04 pm GMT EndGMT ]
Post subject:  Re: Correct panel ('s ) for my application
there's many sources of wire and ultimately you'll probably pick a place that has the best price, but availability could come into play too. if you have building supply stores or hardware stores near you that could be a start, but if no luck try to find a local electrician and ask him the best place to buy around you. to give you a clue as to what gauge of copper wire you may need you can check out the voltage drop calculator on the northern arizona wind & sun forum. http://www.wind-sun.com/ForumVB/showthread.php?t=29 be sure to start at the beginning and read it through, but in general it is an excel type spreadsheet and any similar type of excel program will work. i use open office and that's free. i would say try to use armoured wire if you can so you or any critters don't go through the insulation and accidentally short things. sometimes multistranded wire can be used where a great deal of movement is expected for the wire making it easier to handle and less likely to break from flexing, but if too big in diameter of a wire, it can get difficult to make connections with it.
Author:  mike90045 [ Tue Sep 23, 2008 9:35 am GMT ErdGMT ]
Post subject:  Re: Correct panel ('s ) for my application
For low voltage wiring, and not too high of current, the 12V landscape (malibu) lighting wire is handy, box stores have jumbo spools of it, extra tough insulation for the garden...
Author:  niel [ Tue Sep 23, 2008 1:30 pm GMT ErdGMT ]
Post subject:  Re: Correct panel ('s ) for my application
sorry mike as the application he has in mind is for an rv and not a garden. it could still give another idea of where to look for wire though.
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