Too much shade?

pchiquitpchiquit Posts: 4Registered Users
Hi guys:
     I've been considering Solar PV for a long time but has always been hesitant due to the amount of shade on my roof. Recently I came by the opportunity to acquire 50 panels of CIGS solar panels for $.050 per watt. I'm very tempted but If possible I would like the opinion of more experienced heads if this is going to work or not. I've heard that a-Si panels perform well under shade and I'm assuming that  CIGS panels also share that property, but I'm not a 100% sure. Any real world experience on that?
     To help understand my shading problem I did a time lapse of the house that can be seen here: 
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Comments

  • EstragonEstragon Posts: 2,219Registered Users ✭✭✭✭
    Any pv solar will be badly affected by shade. Some types and/or electrical configurations may be marginally better than others, but none produce much in shade.

    Your time lapse isn't so terrible, showing full sun from about 11am to mid afternoon, which is about when pv production is highest anyway. Taking out a few trees to the east might make a big difference.

    A bigger concern in my mind is the date. It looks pretty green there for late April, so I assume you aren't very far north, but late April is in about the best third of the year in terms of sun angle and shade issues. The worst third (roughly early Nov - early Feb in northern hemisphere) can be a challenge in most locations, but to be viable you really want the late winter and early fall angles to work. Using an online solar elevation calculator, you could work out whether you'll be shade free in these shoulder periods.

    Are the panels you're being offered by any chance flexible panels from a bankrupt manufacturer?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • pchiquitpchiquit Posts: 4Registered Users
    Thanks for the answer. I'm in Durham, NC, so not that far north.
    So if I understood what you are saying, I should look at how does shading looks during Nov/Feb to have a good picture of how much production I'll have on the worse months. According to : http://solarelectricityhandbook.com/solar-angle-calculator.html my angles are:

    Winter
      30° angle
     
    Spring/Fall
      54° angle
     
    Summer
      78° angle

    The solar panels are from a bankrupt company but are glass and not flexible.
  • PhotowhitPhotowhit Posts: 4,481Solar Expert ✭✭✭✭
    CIGS often use cadmium, I wouldn't want to have to worry about the disposal of the panels after their useful life. Not sure how much better they would be in the shade. Less energy is present to do anything with...

    Looks like you get full sun from noon until 4 or so which isn't awful, it does look like you would get more shading in the winter with the sun lower on the horizon.

    You can find traditional panels around 50-60 cents a watt. I would stick with them. I can't find a reasonable analysis right now but I have a lasting impression that CIGS don't have as long a life span as traditional panels.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • BB.BB. Posts: 27,351Super Moderators admin
    I worry that during the winter ~3 months (low sun angles), the house/roof will be blocked by the trees to the south and you will get virtually no useful sun.

    Also, it looks like your trees are probably a fast growing species? In 10 years, you may not have any sun unless you aggressively prune. And "topping" trees is considered a big no-no for their long term health and safety. Can/will you clear the land to the south east through the south west? In my area, tree trimmers are expensive--And if you have to do this every few years, their costs will tend to swamp any money saved from GT Solar Power.

    Panels need full sun to produce anywhere near rated output power. Any shade or partial shading on solar panels just kills output

    -Biull
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • littleharbor2littleharbor2 Posts: 877Solar Expert ✭✭✭✭
    edited April 29 #6
    $0.50 a watt seems quite high for thin film panels from a defunct company. You should be able to find current production silicon based panels from well known and stable mfg. for that price. Careful with thin film panels as they can be considered  toxic waste and the seller is attempting to make a profit off an unsuspecting buyers in lieu of proper disposal. 

    https://sciencing.com/toxic-chemicals-solar-panels-18393.html

    https://dtsc.ca.gov/HazardousWaste/SolarPanels/upload/SolarPanelFAQs.pdf

    Thin film panels are approx. 1/2 as efficient as silicon panels so your proposed 50 panel purchase would take twice the space as would silicon panels for the same output.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • westbranchwestbranch Posts: 5,010Solar Expert ✭✭✭✭
    When I watched that  video, my first reaction is it won't work with out some PERMANENT tree removal. Pruning is just an ongoing problem.
    Then Bill addressed the shade issue.  I will emphasize that ANY shade, like that from a pencil sized branch, will kill at least half of your production, and the further the branch, without leaves on it, is from the PV's, the more effect as the shade pattern is larger ie it shades more of the PV surface.   hth.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • EstragonEstragon Posts: 2,219Registered Users ✭✭✭✭
    It's not so much the angle of the panels (which can be adjusted seasonally for better production as well), but rather the angle of the shadow cast by the trees with lower sun angle in shoulder seasons. At my latitude in winter, the shadow from an object will be several times the height of the object.

    Using a solar elevation & azimuth calculator you can estimate where the sun will be on various dates and times of day. Standing near where the panels would go with this info and an angle tool, will give you a sense of shade problems and possible solutions (like taking out a couple of trees, or maybe a different location for panels).
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.BB. Posts: 27,351Super Moderators admin
    edited April 29 #9
    I think he is looking at $0.05 per Watt... Virtually free. [sorry, apparently $0.37 to $0.50 per Watt, not $0.050 per Watt... -Bill]

    Some things to watch out for... Some CIGS panels must be connected to a load 100% of the time when the sun is shining (they are intended for large solar farms). So they cannot/should not be used off grid (or stored in sunlight unless their leads are shorted).

    Also, check that they are UL/NRTL Listed (typically required for building permits and GT Inverter connections to utility power). And that their Vmp/Imp will work with the Central/Micro Inverters you intend to use (some CIGS panels have very different Vmp/Imp ratings and can be hard to "mate" with typical GT inverters).

    I am not a huge fan of CIGS--I am not sure how well they last in decades of full sun operation... If these are flexible panels--I would suggest walking away from them as they may only have a 2-5 year life or so in full sun (in my humble opinion).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • pchiquitpchiquit Posts: 4Registered Users
    Thanks for all the feedback. 
    @Photowhit I believe the CIGS panels don't have Cadmiun https://en.wikipedia.org/wiki/Copper_indium_gallium_selenide_solar_cells
    but I'm not sure about the Indium and Galium. Will check.
    Here is the panel datasheet and information from the company called STION. 
    http://www.solardesigntool.com/components/module-panel-solar/Stion/2367/STL-135/specification-data-sheet.html
    It looks to be UL certified, but I'm not completely sure as they don't mention it, but there is an mention of UL on the voltage.
    I'm still negotiating the price, but it probably can go as low as US$0.37/watt.
    I don't want to remove the trees from the south side as they provide a buffer with the street.
    Anyway, the feedback that I'm getting is that it will not work that well and my payback is not really guaranteed. So I'm probably going to put this on hold and see if I can research a little more. I really appreciate the feedback and the time you guys spent answering my questions.
    Paulo


  • BB.BB. Posts: 27,351Super Moderators admin
    Those panels look very interesting.

    Should have the ratings you need (you can verify UL online through their website).

    Still need to make sure they match the electrical input requirements to your GT Inverter(s) of choice. These appear to be a difficult match for a 48 VDC battery based off grid system with typical "mid-voltage" range MPPT controllers.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Posts: 4,481Solar Expert ✭✭✭✭
    They are also a frameless design!
    Though ROHS compliant so no cadmium!
    Double glass design so might be longer life...
    I would not assume any payback with any limiting factor with the sun. The margins are very small in general with grid tied solar unless you are in the very sunny southwest, and the Power company is still accepting net metering.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • EstragonEstragon Posts: 2,219Registered Users ✭✭✭✭
    May make sense for self-consumption to offset summer air conditioning cost? Even if the local utility allows grid net metering, I personally wouldn't count on it staying that way on any reasonable economic basis.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • pchiquitpchiquit Posts: 4Registered Users

    Thanks for the additional information. Against the odds I decided to go ahead and install 10 or 12 Jinka Solar EAgle MX panels: 

    https://www.pv-tech.org/products/jinkosolars-optimized-eagle-mx-panels-replace-bypass-diodes-with-high-yield

    The idea is to get a solar panel that will be able to produce even on irregular shading. I'm considering a fun project and not expecting a payback, so I'm going for a small 3kw system where I'll do all the work to see if I can stay at around US$1/kw.
    Thanks again for all the feedback.

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