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Different Sized Panels


JCTex

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I want to hook 3-160W panels in series. Volts are 18.5/22.2; amps 9/8.65. I need 3 more to achieve an array of 960W. Battery bank will be 900A rated AGM. However, those same panels are not available.

 

If I bought 2-260W Astronergy grid tie type panels I could hook them both to the combiner box as a series string of 2 or independently. Volts are 31/38.5 amps are 8.4/8.7. Volts and amps at normal operating temps are less than those numbers. These, plus my 3 low voltage panels, would give me an 1,000W rated array.

 

My down run to the controller is ~15' one way. I'm leaning toward the TriStar 60 controller; but I'm not sure it has the capacity for this array.

 

Please tell me how I can wire up this arrangement of panels.

 

Jerry

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Greater minds than mine will undoubtedly provide more help, but from what I have read in your inital post.. I have to admit I am completly confused.

 

30' is quite a distance. As for me, about all I can confirm is your intent to utilize a Tristar 60 MPPT that is, in all likelyhood, more than capable of handling your solar production, but implementation without more clarification on what your overall system is composed of has me stymied.

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According to this article, your panels are very dissimilar so they would not recommend mixing them as your performance would be degraded. You essentially want to connect 2 arrays of different voltages in parallel. This will reduce the voltage output to the lower of the two - in your case 55.5volts, reducing the output of your two 260 watt Astronergy panels (520 rated watts) down to 55.5 x 8.4 = 466 watts. So your total system output should max at 946 watts connecting them as you suggest, not 1,000 watts. This does not take into account the age of your older panels which degrade over time. Realistically about 935-940 watts is the most you can expect from your proposed system under ideal conditions. Flat mounting the panels is certainly not ideal conditions. I hope this helps. The article explains it better than I could.

 

http://solarpanelsvenue.com/mixing-solar-panels/

 

Chip

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Of course, Id prefer matched panels DUH. However, If I were combining panels in series (not withstanding shading concerns) Id worry less if they weren't perfect matched then if I were to connect two panels in parallel that weren't perfect matched. I don't like the idea of two different panels in parallel at all !!!!!

 

Circuit runs to controller and voltage drop concerns. Of course the bigger the wire the less voltage drop DUH. Once you decide on your series and/or series parallel configuration and know your total max watts and max voltage and know the distance ONLY THEN CAN YOU CALCULATE THE NECESSARY WIRE SIZE

 

Likewise you need to decide on your panels series or series parallel configuration and total max watts and amps to select the Charge Controller capacity.

 

That's a decent sized array. Fortunately my energy use doesn't require quite as much whewwwwwwwwwwww lol

 

John T

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You are not going to be successful with your described scheme. While it will produce power, it will produce greatly reduced power. The article that Chip linked explains it well. I also cover it on my website. This is the very type of thing that people do and then wonder why they are not getting the output they expected.

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My currently-owned 3-160W panels are from AM Solar. They've never been unboxed. AMS tells me their new GO160 has different specs. If the two are reasonably close I'm going to buy 3 more 160's and just accept the lower current that one set or the other causes.

 

I can hook the 3 older, but brand new, 160's in one string and the 3 newer ones in another string, paralleling both strings at the combiner box. The 160's I have now list a Voc of 22.2, or 66.6 PV volts per string. The Isc is 9.65 max load Amps. Is the latter also per string or must I multiply it, also?

 

The TS-60 MPPT allows 125VDC max PV current and 60A max load current; so, I think it would work for my 2 parallel strings above. Am I right about this? I'm amenable to any other MPPT controller; but this one seems to fit and is cheaper than the Classic 150. Outback's FlexMax 60 or 80 are out there, too, but at a higher price. So, confirmation or condemnation of the TriStar would be appreciated.

 

So, I'm waiting for AM Solar to publish the new specs.

 

Jerry

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Pebble, Is it possible for you to connect all your "matched" panels in Parallel (such as 2 or 3 OLD matched ones) and connect your other "matched" panels (such as 2 or 3 NEW matched panels) AND THEN SERIES THE NEW WITH THE OLD???????????????? I'm talkin a Combination Series/Paralell configuration here

 

I ask because I DO NOT like to connect panels in parallel that aren't matched, but I'm fine in parallel if they are matched.

 

I prefer alllllllllllll to be matched, HOWEVER, if in Series but they aren't a perfect match, I have less problem with that versus if they were in parallel.

 

Then for that Series/Parallel combination (2 or 3 matched in parallel in series with another 2 or 3 matched in parallel) and compute total Watts and Voltage and Current.

 

If the Voltage and Current of that Series/Parallel configuration is within the rating of your Solar Controller and IF the vendors engineering tech department says its okay, it "might" work EVEN IF NOT PERFECT if wired that way mixing old and new panels.

 

JUST AN EXAMPLE EVEN IF NOTTTTTTTT WHAT YOU HAVE

 

If you had 2 or 3 OLD matched 12 volt panels in parallel, that's still 12 volts (but can deliver more amps). If you had 2 or 3 NEW matched 12 volt panels in parallel that's still 12 volts THEN IF YOU SERIES THAT, YOU OF COURSE HAVE 24 VOLTS (actually max voltage) sent down to your Solar Controller.

 

DISCLAIMER I prefer "matched" panels, DO NOT suggest unmatched panels in parallel, and am just throwing out perhaps some sort of Series/Parallel wiring configuration "might" ( note I said might) work provided your net total watts and volts and amps is within your controllers specs.

 

BUT DO NOT DO THIS UNLESS THE VENDORS ENGINEERING TECH DEPARTMENT APPROVES IT

 

DO NOT TRY THIS JUST BECAUSE I THINK IT JUST "MIGHT" WORK I dont want to be responsible for trashing your system. CONSULT THE VENDOR NOT ME. Im not there and I dont have the specs and data so I cant say if it will work or not !!!!!!!!!!!!!!!!!!!!! Just exploring possibilities here for a wiring method (old and new in series/parallel) that "might" possibly work. Of course an all matched panel system is preferred, just lookin for other methods here NO WARRANTY

 

The Series/Parallel method I discussed above MAY NOT WORK WITH YOUR PARTICULAR PANELS. Its okay in theory but subject to your particular panels, its ONLY a possible method that might enable the mixing of different panels (utilizing series/parallel) provided similar types are in parallel and dissimilar are NOT in parallel.

 

Let us know what the vendor suggests. Did I mention I don't like unmatched panels in parallel lol

 

John T

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