Arco M65 vs Siemens M65 & stringing

audredger
audredger Solar Expert Posts: 272 ✭✭
in Off Grid Solar & Battery Systems #1
Many, Many moons ago I bought 3 used Arco Solar M65 panels, then bought 2 Siemens M65 panels. Arco Solar was bought up by Siemens and continued to manufacture the M65 however, the outputs changed!?

Arco: Voc 20, Isc 3.68, "rated" 12.8v 3.26a = 41.728 watts
Siemens: Voc 18, Isc 3.23 "rated" 14.6v 2.95a = 43.07 watts

Same; size,#of cells, wiring etc. Did Siemens just use stronger test lights?

Ipmax is within 10% so I could run all in parallel but, would like to series into a MPPT controller

When you figure Vpmax for series do you work from high to low or, low to high?

14.6 - 10% (1.46) = 13.4
12.8 + 10% (1.28) = 14.08

over 10% no matter but, am I still close enough? have a MX60 sitting around and hate the thought of adding a second controller or loosing the watts.

Planning to install in a $100 school (hippie) bus for rock hounding and maybe the playa.
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Comments

  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #2
    Re: Arco M65 vs Siemens M65 & stringing

    Those specs are when new, the Arco's are what, 30 years old now?. At this power level. Its not enough wattage for a MX60 ... better off with an pwm controller
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  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    #3
    Re: Arco M65 vs Siemens M65 & stringing
    Those specs are when new, the Arco's are what, 30 years old now?.
    Last time I checked my 24 watt Arcos are still within 90% of their new ratings. I think that's pretty amazing considering I bought them used in the early 80's.
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #4
    Re: Arco M65 vs Siemens M65 & stringing

    Yes it is pretty amazing Mike, here is the thing; if the Arco's are 30 years old then the Siemens are 29 years old. Both built in Camarillo, CA on the same line, by the same people. Only two things different, the cooperate logo and the color of the "chips". Arco's are black, Siemens are blue. The specs are from the data plate not real world testing.

    These were installed on the airstream, all paralleled together into a C40 controller. The batteries were always slightly undercharged unless I was hooked into shore power. 12.8v from the Arco's just wasn't enough to top them off.

    Haven't found a boost controller that will handle 15.6 amps if I parallel them all together.

    If I put one of the Arcos into the museum and only work with four of them. Series a Siemens with an Arco then parallel to a small MPPT controller, I'm worried that the mismatch of voltage wont work. (Just beyond the 10% rule)

    Perhaps take the fifth Arco and hook direct to the star batteries as a trickle charger?
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #5
    Re: Arco M65 vs Siemens M65 & stringing

    They ratings are probably pre-standards, the 12.8vmp for a 20V voc is doesn't make much sense, all Si panels are about 70% of voc = vmp , close enough for this question anyways

    Just a parallel all the panels with a cheap pwm controller, if the battery isn't getting fully charged then either the battery is toast or you have to much of a load or panels are toast, It could also be the Arcos don't work anymore, you need to connect to a battery with a amp meter to see if the panels are doing anything at all

    The voltage difference are not worth worrying about, thats not the issue as solar panels will charge right up to bulk setting, the only concern would be not getting 100% of the rated power, for example if it is 12.8 vmp, at 14.4 you may only its 80% of the rated watts, but it will still charge the battery, just slower
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #6
    Re: Arco M65 vs Siemens M65 & stringing

    Thanks, will check each panel then see if the old c40 still works. Will be installing new batteries, the old lifeline AGM's are old enough to go off to college so I've gotten my moneys worth...
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #7
    Re: Arco M65 vs Siemens M65 & stringing

    The old Arco and Siemens M65's were advertised and sold as "self regulationg" panels. In fact they had no regulation, they were just low voltage panels, with 30 or 32 cells, usually. There were at least 3 slightly different versions, varying mostly just in the way the cells were cut and arranged. They were sold mainly for RV and similar use to cut the expense of buying a standard panel.
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #8
    Re: Arco M65 vs Siemens M65 & stringing

    "There were at least 3 slightly different versions, varying mostly just in the way the cells were cut and arranged" I guess this would account for the difference in specs.

    " sold as "self regulating" panels" that's scary

    I'll try them all paralleled with the old c40.... if that doesn't work out, I'll do 2x2 series/parallel and buy a small MPPT controller.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #9
    Re: Arco M65 vs Siemens M65 & stringing

    Interestingly, I found a stash of these M52s panels for sale, and a google search for specs led me right back home!

    So does anyone know the real specs on these panels? The only spec I can see is a series voltage of 1000. I assume that these are ~ 52 watts, ~ 17 volt VMP,, or possibly only 12.8 vmp.

    Tony
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #10
    Re: Arco M65 vs Siemens M65 & stringing

    page 11 on the pdf.

    http://geopubs.wr.usgs.gov/open-file/of00-128/of00-128.pdf

    found better link here for many pvs,
    http://pearen.ca/Reference/pv_specs.htm
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #11
    Re: Arco M65 vs Siemens M65 & stringing

    I actually found a link to an old Homepower magazine article that did real tests of a number of panels: http://www.scribd.com/doc/25249135/PV-Performance-Tests

    The problem is there was number of M52's listed so I am not sure which ones these are.

    I'm guessing that the ones that I found are ~ 52 watts, somewhere in the 17 volt range.

    I found ~ 600 watts worth for $ 400 including shipping so I am trying to decide if I wish to take a gamble,, ~ $.66/watt.

    Tony
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,022 ✭✭✭✭
    #12
    Re: Arco M65 vs Siemens M65 & stringing

    Tony,
    At 66 cents per watt it'd be worth building a shed just to mount the panels on! Maybe a gazeebo on the dock?

    Ralph
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #13
    Re: Arco M65 vs Siemens M65 & stringing

    My thoughts exactly. Also, to keep a few spares for when a branch falls through a panel, or if, as they always do,, the loads grow.

    The seller claims that they put out 7 volts, which makes no sense. I am having him test again in full sun.

    Tony
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #14
    Re: Arco M65 vs Siemens M65 & stringing

    Keep in mind they are 30 year old panels, so your $$ watt is likely off by at least 2X and those old panels had issues with the encapsulation hence why they were pulled for service, they came from some trough tracker system in CA from the 80's I believe.

    $600 is cheap, but don't forget the cost of racking, wiring, fusing ect ... 3 new non-ul evergreens would do the same task and have 30 year life for probably not a lot more
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #15
    Re: Arco M65 vs Siemens M65 & stringing

    SG,

    Thanks for the help. Explain if you can what is meant by "encapsulation"? What would you guess the Vmp and Imp would be on these panels, as the labeling has none of that information. What should a Voc look like?

    I am not going to install all of them, I might just add a couple as a second string for bonus power, and either sell or store the rest. At ~$.66/watt including shipping it almost seems hard to go wrong,,, But everyone knows the costs of some bargains.

    The cheapest I can find other ~17 vdc panels is ~ $1.70 -$2/watt by the each.

    Tony
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #16
    Re: Arco M65 vs Siemens M65 & stringing

    "The Carissa Plain plant covers dozens of acres of land with photovoltaic arrays mounted on two-axis trackers. Mirrors, placed next to the arrays, help reflect light to increase the potential power output. Unfortunately, the intense reflected light has partially destroyed the protective module coatings and has actually decreased production of electricity. Further development of better coatings should solve this problem."

    Built in 1982 and dismantled some time after 1984, that's were most of these old modules come from.

    Even if perfect, you can't compare today's panel ratings to those from 30 years ago, it wasn't he same standard. You need to derate by at least 50% to account for age,condition and partial failures when comparing to brand new 2011 stock, so 1,30 vs 1.70 ( no risk on the new stuff ) isn't that much of a bargain. And there is lots of panels now approaching buck a watt
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #17
    Re: Arco M65 vs Siemens M65 & stringing

    Thanks SG,

    Useful information,

    T.
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  • peakbagger
    peakbagger Solar Expert Posts: 341 ✭✭✭
    #18
    Re: Arco M65 vs Siemens M65 & stringing

    I have specs on M75's in case someone needs them. I have an array of 20 of various vintages, unfortunately the majority of them have a factory defect (long out of warantee) with the tabbing but they still put out over the orginal rating on a cold sunny day with snow on the ground.

    I have been looking for a source of the panel junction box covers as I am missing a few, if anyone has some dead panels with the covers, I would love to buy the covers.
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