Polycrystalline vs Monocrystalline Solar Modules

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Polycrystalline vs Monocrystalline Solar ModulesMost solar modules used today are either polycrystalline or monocrystalline, otherwise known as mono and poly.* So what is the difference between polycrystalline and monocrystalline? For the sake of brevity, the difference between the two is that monocrystalline is composed of a single crystal of silicon, while polycrystalline is composed of many crystals. These two [...]Solar Feeds Related...

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  • CDN_VTCDN_VT Solar Expert Posts: 491 ✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    MONO SOLAR vs POLY SOLAR
    I found this also ? Link

    And direct : http://www3.telus.net/public/tps.x/information%20center/Mono%20vs%20Poly%20Cells.doc

    Word DOC , but has some points.

    VT
  • Jim45DJim45D Solar Expert Posts: 102 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    I have both and can not see any differance in color. They are all dark blue. However, here's a snippet I saved. I used to obsess about this....finally gave it up. They work.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    jim,
    the last line on that snippit is key. because of that it will often boil down to costs as the small area the mono pvs save with higher efficiencies does not make a huge difference to most people as one would only be able to add extra pv only after many have already been installed. that is, each mono may free up 2-4 inches over the poly counterpart.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules
    niel wrote: »
    jim,
    the last line on that snippit is key. because of that it will often boil down to costs as the small area the mono pvs save with higher efficiencies does not make a huge difference to most people as one would only be able to add extra pv only after many have already been installed. that is, each mono may free up 2-4 inches over the poly counterpart.

    Exactly! Unless you're really squeezed for space, go with the most watts per dollar. Some panels are advertised as being higher than standard efficiency, leading one to believe that means more power for you're money, when in reality it's just the opposite. You generally pay a premium for a "hi efficiency" panel, which is a slightly smaller panel that gives the same power as a slightly larger, "lower efficiency" panel.
  • solarixsolarix Solar Expert Posts: 713
    Re: Polycrystalline vs Monocrystalline Solar Modules

    My question is: which degrades faster, Poly or Mono? Does the Mono age better because it is a higher quality crystal to start with, or does the poly age better because it is already "fractured up"?
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules
    solarix wrote: »
    My question is: which degrades faster, Poly or Mono? Does the Mono age better because it is a higher quality crystal to start with, or does the poly age better because it is already "fractured up"?

    They're made of the same basic material, so except for Ultra Thin types which don't seem to last as long before degrading, you should find no difference in their overall life, all other things being equal.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    do note that i was looking for this thread among a few that are similar and decided it would be good to put it here and sticky it.
  • Lee DodgeLee Dodge Solar Expert Posts: 112 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    I am monitoring three PV system, a monocrystalline Si high efficiency (18.1%), a mono Si lower efficiency (14.4%), and a polycrystalline Si (13.9%) all in the same small town, and so far they are all performing the same when normalized by their rated DC power. So far, there is no difference in degradation, but it is too soon to really evaluate that question.
  • SolarPoweredSolarPowered Solar Expert Posts: 626 ✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules
    Lee Dodge wrote: »
    I am monitoring three PV system, a monocrystalline Si high efficiency (18.1%), a mono Si lower efficiency (14.4%), and a polycrystalline Si (13.9%) all in the same small town, and so far they are all performing the same when normalized by their rated DC power. So far, there is no difference in degradation, but it is too soon to really evaluate that question.

    I would like to see your data if this is infact true.
    monocrystaline has a lower level of internal resistance being that the process of manufacturing makes the silicone a higher purity to lower density ratio to that of poly/multi crystalline.
    the purity of multi/poly crystalline is lower also yielding a higher density in weight creating higher internal resistance.
    resistance and level of purity are the contributing factors to conversion efficiency per metered squared.
    Resistance is a form of heat, since the density of multi/poly is heavier and less pure, internal resistance becomes higher as ambient temperature rises, where as mono crystalline suffers less resistance deficiencies as ambient temperature rises.
    A watt is a watt..... Sure according to STC name plate, however PTC fluctuates temperature. STC in many ways is manufacturers cheat method for standardizing name plate, but no where is there a level of tolerance to temprature listed on name plate badging.
    Hense there is a reason why NASA/Boeing hasn't used poly/multi crystalline cells for the past 20 years.
    companies in the mono crystalline biz claim a higher yield per real estate annualized, it's a key sales pitch for most high efficiency solar firms.

    Here is the advantage and disadvantage of mono VS. poly. There is some info that has some inaccuracy as if a novice wrote the article as the piece on advantage and disadvantage of poly in many ways contridicts the advantage/disadvantage of poly.
    The article is slightly outdated claiming the cost of mono is higher than poly. That has since changed in the past few years as the manufacturing technique of mono has become more cost efficient than poly, and the price per watt is evenly matched to STC name plates.
    Read the disadvantage of Poly.

    http://www.gwynedd.gov.uk/swiftlg/imagetemp/42432-253768.+21.09.12

    Mono crystalline by far is more superior and the manufacturing techniques are improving for higher efficiencies exceeding 25% on the cell level.
  • Lee DodgeLee Dodge Solar Expert Posts: 112 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules
    I would like to see your data if this is infact (sic) true.
    ...snip...
    The detailed performance results for the three systems that I am monitoring are provided here.

    System #1 is a monocrystalline silicon SunPower system rated at 3.15 kW (DC) with an efficiency rating of 18.1%.
    System #2 is a monocrystalline silicon Sharp system rated at 2.82 kW (DC) with an efficiency rating of 14.4%.
    System #3 is a polycrystalline silicon REC system rated at 3.68 kW (DC) with an efficiency rating of 13.9%.
    These three systems are all located in the same small town, and are exposed to approximately the same weather and solar insolation. Systems #1 and #2 have the same orientation, while system #3 has a less optimal orientation, with details given in the link above.

    Because of their different orientations, they are compared to predicted performance by the PVWatts Version 2 model that accounts for orientation effects. They all perform much better than the predicted performance by PVWatts, but they perform similarly to each other when normalized by their rated power, and when account is taken of their orientation. This may be seen in the above referenced data. I will try to add some summarized performance data for each of the systems over one-year periods to provide a more quantitative comparison of the performance of the systems.
  • SolarPoweredSolarPowered Solar Expert Posts: 626 ✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    That still isn't the answer I was looking for.....

    That data of dialogue that you provide is power potential of a complete system after derated compared to PV watts derated calculation. That has nothing to do with what I asked based on temperature coefficient between mono and poly crystalline.

    Since you say there is no difference between any of the mono or polys that you installed lets take a closer look by reviewing the spec data sheets between the REC poly and the Sun Power Mono.
    Attachment not found.

    So for every 1* celcius rise in temprature the sunpower mono outperforms the REC solar poly by .08% per every 1* rise Celcius, and it uses 5% less real estate than the REC panels, I'd say that is pretty powerful for mono.

    People typically disregard temp coefficient and just stick to STC name plate. I would say that isn't the way to purchase a panel that you want to handle in a real world condition.

    Now there are cheaper mono cells that under perform poly... All panels have varying characteristics, but when the margins in loss are within +/-.10% mono crystaline still wins hands down because conversion efficiency uses less real estate so you buy more watts according to the STC, and even at .10% greater loss in temperature coefficient than poly, mono still makes more power within a small surface area, because the panels in comparison are 15% to 20% smaller. So in order for poly to actually be better than mono when comparing to conversion efficiency, mono crystalline temp coefficient would have to be more than a .20% greater loss to that of poly crystallin temp coefficient.MONO is better. A WATT is not just a WATT in the land of PTC.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    Within reason, the slight differences in efficiency are not important to me as I'm not cramped for space. For me, if the panels are reasonably similar, then quality of construction, life expectancy and price are more important than going for the top claimed efficiency. Given a choice and all other things being similar, I'd also pick panels that might offer better than average conversion of diffuse light as there are lots of cloudy days where I live.
    But as always - - to each their own. It would be a boring world if everyone thought the same way.
  • stephendvstephendv Solar Expert Posts: 1,571
    Re: Polycrystalline vs Monocrystalline Solar Modules
    So for every 1* celcius rise in temprature the sunpower mono outperforms the REC solar poly by .08% per every 1* rise Celcius, and it uses 5% less real estate than the REC panels, I'd say that is pretty powerful for mono.

    People typically disregard temp coefficient and just stick to STC name plate. I would say that isn't the way to purchase a panel that you want to handle in a real world condition.

    This can work the other way around too. E.g. in many off-grid setups, the marginal months with high loads vs low solar power are in winter. So for these types of setups it would be better to have a "worse" temperature coefficient, i.e. pay for a 240W STC panel, but effectively have a 250W panel in winter and a 230W panel in summer; so in that case Poli would be better.

    And conversely for grid tie applications or for off-grid homes where summer months are the marginal months, e.g. heavy AC use, then it would be better to go with the mono panels.
  • PNjunctionPNjunction Solar Expert Posts: 762 ✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    Wouldn't this all come out in the wash anyway with the use of an MPPT charge controller?
  • SolarPoweredSolarPowered Solar Expert Posts: 626 ✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules
    PNjunction wrote: »
    Wouldn't this all come out in the wash anyway with the use of an MPPT charge controller?

    Depends. 12V panels don't need MPPT, then its an issue of portability.
    I just traded (2) of my 12V 100 watt mono crystalline panels for (1) 24V serengety 228 watt poly, I came up 28 watts on that trade, so to me the mono 12V's have more value. For reasons the 12V's don't need MPPT.
  • Lee DodgeLee Dodge Solar Expert Posts: 112 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    Over the year 2012, the three systems that I am monitoring all significantly outperformed the predictions by PVWatts (Version 2). The specific results, which are real world measured performance, not spec sheet data, were as follows:

    SunPower Monocrystalline Si 22.6% above PVWatts predictions
    Sharp Monocrystalline Si 23.5% above PVWatts predictions
    REC Polycrystalline Si 18.9% above PVWatts predictions

    For 2011, I only have complete-year data for the SunPower system that produced 19.8% above PVWatts predictions. I am seeing similar results for 2013, but, of course, those data are not complete for the year. The PVWatts predictions have included a degradation factor of 0.65% per year, as well as corrections for panel orientation. The detailed results are shown at http://www.residentialenergylaboratory.com/comparison_of_pv_systems.html. I do not know why all three systems outperformed PVWatts predicitions by such a large amount, but certainly weather is variable year to year.

    The SunPower system has a higher efficiency specification than the other two, 18.1% versus 14.4% and 13.9%, but as others on this thread have pointed out, this difference is only significant if roof space is limited. I regard the performance of the monocrystalline and polycrystalline silicon systems as similar for the data measured to date.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules

    Excellent report "Lee Dodge". Thanks for sharing with us.
  • SolarPoweredSolarPowered Solar Expert Posts: 626 ✭✭✭
    Re: Polycrystalline vs Monocrystalline Solar Modules
    Lee Dodge wrote: »
    SunPower Monocrystalline Si 22.6% above PVWatts predictions
    Sharp Monocrystalline Si 23.5% above PVWatts predictions
    REC Polycrystalline Si 18.9% above PVWatts predictions

    I do not know why all three systems outperformed PVWatts predicitions by such a large amount, but certainly weather is variable year to year.

    The SunPower system has a higher efficiency specification than the other two, 18.1% versus 14.4% and 13.9%, but as others on this thread have pointed out, this difference is only significant if roof space is limited. I regard the performance of the monocrystalline and polycrystalline silicon systems as similar for the data measured to date.

    4% performance advantage for mono VS poly is pretty common. Lower light intensity conversion levels is what mono is known for, better production from cloud cover, shade, early morning sunrise, and late evening sun fall. So for a system that yields 100,000kwh annually thats a performance benefit of 4,000 kwh annually.

    PV watts essentially takes the bare bone derate factors according to NEC, if a system performs lower than those factors than there is a huge problem.

    The big factors for the PV watts difference to PTC, is soiling and conductor derates, both sunpower and PV watts account for a huge soiling factor, as if sand storms are frequently hovering PV. Also take into account the conductor de-rate factors from both sun power, and PV watts. A practical calculated conductor derate shouldn't exceed .12% for residential, the conductor lengths shouldn't be spanning over 100', and 4AWG is readily feasible for most inverter installations under 10kwh. Now take into account a commercial project, and conductor runs are obviously more practical to exceed over 100' lengths the conductor de rates are more common to be around .55% and over 25kwh requiring up to 500 mcm/kcmil.

    I'm willing to bet that 1% marginal difference between sunpower VS Sharp systems just boils down to bottom dollar costs on conductor, conductor length. More than likely the sunpower system has a longer conductor run, and may use the same conductor sizing as the sharp system. Just my opinion based on the few hundreds of installs I've performed.

    Thats why the term I like to use is dumb it down. PV watts dumbs down the calculations so any plethora of incompetent end users can use the data and say this is what I can invest into.
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,258 ✭✭✭✭
    Also an advantage for Sunpower and Panasonic / the old Sanyo panels is they perform better than Poly at high temperature. The other obvious advantage as said, they outperform on a tracker because more can be packed in a defined space.
    It is more than 1% better when size is factored in and this all becomes a numbers game with commercial tracking systems that I am glad to watch from a distance. Good job for a PHD out of college.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • softdownsoftdown Solar Expert Posts: 1,498 ✭✭✭✭
    On several occasions, I have read that mono panels lose efficiency at a significantly lower rate than poly panels. So if one looks 20 years down the road then mono may be the go to panels.

    I'm amazed by the power output of my panels. My batteries storage capacity? Not so much. Also...solar doesn't do much in cloudy weather...
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 150 watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • SolarPoweredSolarPowered Solar Expert Posts: 626 ✭✭✭
    softdown wrote: »
    On several occasions, I have read that mono panels lose efficiency at a significantly lower rate than poly panels. So if one looks 20 years down the road then mono may be the go to panels.

    I'm amazed by the power output of my panels. My batteries storage capacity? Not so much. Also...solar doesn't do much in cloudy weather...


    Sunpower Panels which are mono crystalline back contact, and LG MonoX panels suffer the least depreciation of all panels on the market, at under .42% depreciation.

    I believe the E20 class maxion 2 generation of sunpower panels depreciate at under .35%, according to the test conditions, sunpower will produce and harvest 8% more power over the course of 20years VS conventional poly panels.
    http://us.sunpower.com/sites/sunpower/files/media-library/data-sheets/ds-e20-series-327-residential-solar-panels.pdf

    Sunpower Grade B panels however are variable to name plate depreciation, unlike the grade A name plate rated counter parts. the B grade are still a big bang for the buck.
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Well i wonder if a more efficient panel, ie one that takes up less space, will suffer less from temp coeffcient losses. Theoretically, a panel that was zero size would have no PTC at all. ;)
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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