Monocrystalline vs Polycrystalline Photovoltaic Cells

You may have heard the terms monocrystalline and polycrystalline used to describe photovoltaic cells, but what does that mean and how does it affect a cell’s performance?

Basic Anatomy of a PV cell

Pure Silicon

A lump of pure silicon

The main ingredient in most photovoltaic cells is silicon – the same element that makes computer chips possible.  Silicon is the second most abundant element in the Earth’s crust, but unfortunately it is normally found in the form of silica (the chemical symbol for silica is SiO2) – you might know it as sand.

Various methods exist to extract the pure silicon, but the most common is carbothermic reduction, where the silica is heated to 1700°C in the presence of carbon.  As the silicon cools it forms crystals.

The speed at which the silicon cools is one of the critical factors that determine the crystal size: the slower the silicon cools, the larger the crystals.  With care the silicon can be extracted as one large crystal.  As you might imagine, that’s more difficult, which means it’s more expensive.

The difference between monocrystalline vs polycrystalline solar cells is simply that one is produced from a single crystal of silicon and the other is produced from a piece of silicon consisting of many crystals.

Practical Differences

So what is the impact on cell performance?

Since polycrystalline cells contain many crystals, they have a less perfect surface than monocrystalline cells.  This means that they absorb slightly less solar energy and produce slightly less electricity per square metre. On the plus side, the process of creating the silicon for a polycrystalline cell is much simpler, so these cells are generally cheaper per square metre.

On balance, the cost of monocrystalline vs polycrystalline based panels per Watt of power output works out about the same, but the polycrystalline panels will be slightly larger than equivalent monocrystalline panels.  This is generally not a problem unless you have a very limited area available for the installation, in which case you will want to maximise the power output per square metre.

Monocrystalline and polycrystalline can also look different.  Monocrystalline cells will usually have a perfectly uniform appearance, but polycrystalline cells will appear “grainy” – think of how a granite worktop looks and you’ll get the idea.  From a distance this will not be noticeable, so if they are going on your roof this is unlikely to worry you.

So which should I choose?

At the end of the day, unless you are very space constrained, your choice of panel will probably be dictated by factors other than whether they are made up of mono or polycrystalline cells.

The price per Watt is an important factor, and that is largely unaffected by the choice of monocrystalline versus polycrystalline cells.  In some circumstances, the area available for the installation may be a factor that pushes you to go for monocrystalline cells.

But the most important thing is to make sure that you choose a reputable installer and manufacturer.  Your panels will most likely give you many years of trouble free operation, but for your own peace of mind you will probably want to choose a manufacturer that is likely to be around for long enough to honour the terms of the guarantee – which may be up to 25 years!

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Category: PV Panels | Tags: | 32 Comments
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  1. Posted July 17, 2010 at 12:24 pm | Permalink

    Around 14% space is saved by using monocrystalline panels which is substantial when we think of installing multi MW solar power plants as each MW requires around 5 Acres of land.

  2. Andy
    Posted July 18, 2010 at 8:21 am | Permalink

    I agree – when you start looking at large installations then the space saving due to monocrystalline panels can be signifcant. This is something you need to factor into your financial calculations. But for smaller installations (e.g. domestic installations), where space is less of a constraint (unless you plan to cover the entire roof in panels), then this is less important.

  3. sgk
    Posted December 23, 2010 at 5:11 am | Permalink

    thank you all

  4. Posted May 3, 2011 at 2:52 pm | Permalink

    We are waiting for planning approval to fit PV to whole of factory roof ~20kw. Debating over using less but inclined south facing panels with higher average annual output or flat to low pitch roof and fit a lot more (no shading from previous row)with lower installation cost but less output per panel. Neck and neck over annual output supported by trials we have done to simulate through days ranging from dull cloudy to full sun but only with polyctrstaline cells. Does the performance advantage of mono over polycrystal hold true in cloudy over cast conditions (majority of year) or just direct sun?
    Does any one actively cool panels or ventialte them as all seem to be sealed and would expect temperature to rocket and efficiency rapidly drop off in sun?

  5. Andy
    Posted May 4, 2011 at 10:43 pm | Permalink

    In cloudy conditions, mono are not likely to have much of a performance advantage (if any) – though it depends on the particular panels. I’ve seen it argued that polycrystalline cells are better than monocrystalline cells at collecting diffuse solar energy (like you would get on a cloudy day) due to the imperfections at the crystal edges. I think in practice it’s going to depend on the details of the panels you are looking at.

    I’ve seen schemes to cool panels in really hot places (e.g. Dubai), but I’ve never heard of it being done in the UK. The panels will get hot and efficiency does drop off as they get warmer – you’ll lose something like 0.4% of the power output for each degree increase in panel temperature (depending on the panel specs). Maximum power is measured at 25degC, in the UK panels will probably reach something like 50degC on a fairly hot, sunny day, so they’d lose about 10% of their output in that case. Coming up with a scheme to cool the panels that uses less energy that it saves is going to be tricky (it starts becoming worthwhile in desert environments where you see much higher cell temperautres). Depending on how the panels are mounted you might get some airflow underneath the panels which may give a small cooling effect, but I doubt it would make much difference.

  6. phdlife
    Posted May 18, 2011 at 5:36 am | Permalink

    I’ve just had a salesman tell me they use poly rather than mono because it is more efficient in the hot weather (ambient temps around 30C common in summer here). Anyone got anything to say about that?

  7. Posted July 23, 2011 at 3:16 pm | Permalink

    I have been thinking of installing Solar Panels and would like to know if the poly or mono panels would work better were i live, i’m from the North East and would love to here from someone if the mono panels work better in the cloudy type of weather that we have up here? I know that the poly type panels are cheaper but i have been told that even with the best of panels installed that it is the inverter that makes all the difference to converting the energy into power. The inverter i have been led to believe is the best is the SMA Sunnyboy or the Power One Aurora models, and that for the panels, Sanyo or Schucco. Please if you could help me out that would be great.

    James Whittaker

  8. Posted July 24, 2011 at 1:33 pm | Permalink

    Hi James, When making the decision to go for poly or mono you can start by comparing the £/Watt of the panels being offered by your installer. To get the most from your roof you will typically want to have the most Watts installed – i.e. usually this means getting as close to the 4kW Feed-in Tarrif threshold as you can afford (or have room for on your roof). The inverter is equally as important so ask your installer what types they are offering (more expensive ones will have a higher efficiency).

  9. Rose Lacey
    Posted September 18, 2011 at 9:03 am | Permalink

    I have just had a visit from a solar compamy and they have estimated something like £19000 for 4kw (16 panels with monocristals). I am about to have another solar company visiting and wondering if this figure is good or of the scale. Rose

  10. Posted September 19, 2011 at 9:23 am | Permalink

    Hi Rose, We are working with the Energy Saving Trust (EST) to determine typical PV system costs in the UK. It is diffcult to say with a great deal of certainty as you can buy different quality panels/inverters and there are other issues to consider such as ease of roof access and the condition of your roof. The figures we are going to use on our Solar Energy Calculator, which is going to be release on the EST website in a few weeks, are £15,440 for a 4kW system.

  11. karl
    Posted October 8, 2011 at 11:53 am | Permalink

    Hi Rose. I have just had a 4Kwp system fitted for £11500 by apollo solar of huddersfield. The system uses european made panels from a company called Siliken, which are ment to be the best performing panel avalable and a power one inverter, the price also included a 10 year warranty and a smart meter so i can view my system performance in the internet. Very good value for money. I did have a solar company quote £18000 for a 3.9Kw chinese system, but then they said they could do it for £13500 if i signed today. So beware, their are some unscrupilus solar companies out there

  12. reece
    Posted October 12, 2011 at 9:19 am | Permalink

    ho rose
    weve just had a quote for £10300 for 4kw system (LG mono panels X 16) this is in lincs, i think you need to shop around.

  13. LR
    Posted October 12, 2011 at 1:22 pm | Permalink

    Hi Rose My quotes are coming back at around the £10k-£11k mark for a near 4kW system. In the North East, but they work all over the country so £19k is too much!

  14. EASys
    Posted November 11, 2011 at 3:55 am | Permalink

    So many foolish questions…
    There are scamers out there…buy American source so you can take action if necessary, get service from a long term provider-one that is going to be around awhile. Me I would never buy any foreign PV Cells because they have learned to use Boron to increase the output temporarily for falsified Watts/$
    Dont worry about the angle of the sun so much. Close your eyes, that is zero, the difference in exposure has affect, but not so much as to worrry about it. I have had a charge from my panels on a full moon clear night and from city lights. You can also build to recycle your lights by putting panel inside at the apex of the roof line behind window near the peak of your ceiling. Just get onboard, and get ready to charge your electric car for free xportation.-JPH

  15. rina
    Posted November 23, 2011 at 5:58 am | Permalink

    Gopd day

    Here in South Africa we have the mono panels and also the CIGS panels a creation of Dr Vivian Alberts Are there any one out there who is using these panels and what are their experience of such a panel. We have to make a choice between the mono chrystaline and these CIGs panels, as later is cheaper?

  16. mike williams
    Posted January 23, 2012 at 6:45 pm | Permalink

    just had a quote for an 8 panel system 4 each side of sunny aspect roof,of £11900. SAP calculation has number of panels 4/4 panel output 200/200, panel output .64 / .64 (0.8 x panel output).
    annual solar irradation is 997 / 686.

    Need help in understanding it all and is it good value. Panels are monochrystline.

    Replys and help would be appreciated.

  17. Graham
    Posted January 29, 2012 at 4:49 pm | Permalink

    I have just had a quote of £10,350 for 3.5Kw of Sharp NU series monocrystalline panels in Essex with a Sunnyboy inverter. I can only get 3.5Kw of these panels on my roof due to obstructions like ventilators etc. Being slightly more efficient than poly the mono allows me to get nearer to the magic 4KW limit for the higher feed in tariff.

  18. Graham S
    Posted February 5, 2012 at 9:43 pm | Permalink

    This link says monocrystalline panels suffer less efficiency loss at high temperatures.

  19. thiagu
    Posted February 26, 2012 at 8:36 am | Permalink

    1.I want to know, what is the different between Polycrystalline and monocrystalline.

    2.What about the power capacity of the panels.

    3. what are the basic things we want to consider during the commissioning.

  20. nicholas
    Posted March 13, 2012 at 9:16 pm | Permalink

    Keep reading man, Keep reading!

  21. Chook
    Posted April 13, 2012 at 10:40 am | Permalink

    Has anyone wondered what the carbon footprint is to Manufacturer a 3kw system.

    “Various methods exist to extract the pure silicon, but the most common is carbothermic reduction, where the silica is heated to 1700°C in the presence of carbon. As the silicon cools it forms crystals.”

    Who was the cRaZy scientist that said the universe has a set amount of energy? If this is true, is using PV really moving energy from manufacturing the system to actually saving energy while using them?

  22. Posted April 15, 2012 at 6:36 pm | Permalink

    The Energy Payback Time (according to figures published by the EPIA) is less than two years for crystalline installations in sunny countries. It used to be over 20 but the manufacturing process is getting more and more energy and cost efficient.

  23. Bob
    Posted April 30, 2012 at 1:48 pm | Permalink

    I am looking to install a solar panel on a boat to offset a fridge and other small appliances. I convert DC to AC through my inverter and have 4 6volt batteries in series for storage. I have been looking at a 100 watt panel monocrystalline or a 230 watt panel polycrystalline made by Astroenery. Any advice would be helpful. I am not sure of the amps of the 230 watt panel and I am not sure if that is important.

  24. Posted May 8, 2012 at 10:44 pm | Permalink

    hi all,

    i have 3panels in home,two are monocrystalline,one polycrystalline.i joint together one poly and one mono.does it affect the performance when joining both mono and poly.any ideas of you guys are welcome.

    anyway i live here in the philippines,and the climate is is summer-very hot.

    thank you and god bless..
    alan morales

  25. Posted May 11, 2012 at 3:50 am | Permalink

    We just set up a company to sell kits and system parts. The prices you are paying are double what we currently sell. Panels we have are 225W at $1.50CDN/watt Depending on quality of grid tie inverter German made are $3,000.00 CDN Chinese are around $1500.00CDN Our supplier ships from closest location to customer to reduce shipping costs. Our patented wind turbines are $.70/watt $1680.00/2400W 130″ dia blade made here in Calgary AB. Canada

  26. Posted May 11, 2012 at 3:59 am | Permalink

    Oh yeah I mist panels with water from rain gutters in underground tank, recovery is high, very little evaporation. Roof is shielded by panels so building stays cooler and back of panels is cooler. Efficiency is improved but not as much as by angle of panel to direct sun angle 90 degree. This is far more important. We generally have moderate temp breeze. Ambient rarely gets above 30C in summer and panel hits about 53C without misting. In winter at -5C to -20C panels have no temp power loss. I generate 11Kw on my shop and pay no electricity cost and use surplus to negate my gas heating cost.

  27. Posted May 11, 2012 at 4:11 am | Permalink

    I have dealt with Germans, Chinese, American, Danish etc. The Chinese are no better or worse than anyone else. You have to check out the company. China has invested 100 times the money of the USA in engineering and solar industry. Their panels are just as good as the current European panels. There economy is entering a crisis so they can beat out other countries pricing. As an electronics engineer I do rely on other companies power electronics. IGBT’s inside, IR, Siemens, ON Semi Fairchild, Texas Inst. Toshiba and others all make better longer lasting capable of more surges and abuse than some coming from China.

  28. Colin
    Posted May 11, 2012 at 10:03 pm | Permalink

    I’ve been selling and getting involved with hundreds of Pv installs the arguments about poly and mono will go on for ever. In Germany many poly modules were always coming out on top….monos are cheeper to produce and that’s the only difference in my book….I’ve installed many poly jobs and in most cases they out perform monos….poly have the edge with out cloudy conditions….side by side with a top brand manufacturer my money’s on the poly…..SolarWorld 235 poly is awsome and held top spot for years….like someone said earlier for a domestic user it’s the power out-put and the guarantees that count unless your fitting a huge roof don’t get to concerned about small % here and there…..make sure you use a highly qualified electrician and he will make all the difference. Make sure it’s sized right and the inverter is high end like SMA or Power-one and there are many others.

    As an excersise with anyone selling you a system… an example down load a PDF for a aurora 3-6 look at the spec google all explanations on spec and then quiz the salesman, if he gets two wrong kick him out because he should know his product back to front or don’t sell it…..and anyway any-one who buys on the night don’t !!! If they are MCS and a member of REAL they are not following the code of practice by REAL…a good salesman should focus on his product to help the customer and put them at ease by telling them I will not be taking an order tonight and send the customer a quote. :)

    If anyone is paying over 10k for a 4kw you are being robbed……

  29. Kristine
    Posted June 14, 2012 at 10:46 am | Permalink

    Which solar panels are the best to work in areas where there’s a lot of cloud cover?

  30. Frank
    Posted June 16, 2012 at 2:17 am | Permalink

    Interesting comments. I am looking at installing a system on my roof in Toronto, Canada. 6.3 Kw using 250 watt Siliken panels and a Solar Edge inverter with Solar Edge power optimizers on 3 sections of my roof- South, East, West. Not the best but the numbers look ok for selling to the grid. Cost is $35,500 Cdn or about $5.5/kw. The Silikens are poly and seem to be quite comparable from a spec point of view to other panels if not slightly better.

  31. alan
    Posted June 28, 2012 at 10:23 pm | Permalink

    of course you choose a polycrystalline solar panel,its best for cloudy,much better on a sunny day.


  32. John Pullin
    Posted September 30, 2012 at 10:15 pm | Permalink

    There is a company selling the knowhow from the u.s. on how to build our own pv panels and make an installation. Is this for real or a con. Have any commentators experience of diy on this level?

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