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Data and monitoring: Solar tracker with MPPT data

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    • CommentAuthorGBP-Keith
    • CommentTimeDec 21st 2008
     
    I'll take a look at the may data Ed.

    hotelrefurber,
    1. I cannot give averges other than what you can see in this thread:
    http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2342&page=1#Item_9

    until a year has elapsed.

    2. To replace my batteries with secondhand forklift batteries (the most common choice for offgridders) would probably cost about £4000. However, i believe that providing i can keep my generation higher than my demand my batteries will have an almost unlimited lifespan. batteries seem to die when they constantly kept close to discharged. I expect mine to just act as buffers.
    • CommentAuthorGBP-Keith
    • CommentTimeFeb 3rd 2009 edited
     
    • CommentAuthorGBP-Keith
    • CommentTimeFeb 3rd 2009 edited
     
    January 2009. The tracker spent many days locked down and facing South during December and January because there has been adequate wind resource (see my offgrid data in another thread). I don't see the point in exposing the array to extreme windy conditions unnecessarily.
    • CommentAuthorGBP-Keith
    • CommentTimeJun 23rd 2009 edited
     
    This 750w array has produced a total of 1160kWh in the year since last June. my little brain suggests that this is a performance increase of about 58% over a static array of the same size assuming an average (probably generous) yield of 960 kWh/kWp.


    Yields are explained quite well here: http://lightbucket.wordpress.com/2009/03/10/rooftop-solar-power-in-the-uk-–-real-world-data/

    "The “yield” of a photovoltaic system is the amount of energy it produces in a year divided by the rated peak capacity. The units of yield are usually kilowatt-hours per kilowatt-peak. This quantity is just another way of expressing the ratio of mean power-to-peak power.

    Yields on the domestic PV systems in the field trial varied from below 400 kWh/kWp to over 900 kWh/kWp, but the largest number of sites was in the yield range 701–800 kWh/kWp. This range of yields is equivalent to a mean power-to-peak power ratio of 8.0%–9.1%, about what you’d expect for UK insolation levels."
    • CommentAuthorSimonH
    • CommentTimeAug 12th 2009
     
    Hi Keith,

    Have you got any upadted figures for this lovely "summer" we're having? I was wondering if it means outputs are 10%, 50% or 90% lower than usual!

    I'm currently putting together a proposal for a series of community owned PV plants, so would like to get some min/max figures dependent on weather. Currently using an assumed 750kWh/year per peak KW.

    Cheers,

    Simon.
    • CommentAuthorbillt
    • CommentTimeAug 12th 2009
     
    You should go to the PVGIS site - http://re.jrc.ec.europa.eu/pvgis/.

    That should to give you a good idea of the output of your proposed system.
    • CommentAuthorstephendv
    • CommentTimeAug 12th 2009
     
    Simon, bear in mind that Keith has 2 setups:
    1 with a mechanical tracker AND an MPPT charge controller
    1 with a static array and a non-MPPT charge controller

    There is a third option, that many people go for, and which is quite cost effective, which is static array with MPPT charge controller.
    • CommentAuthorGBP-Keith
    • CommentTimeAug 12th 2009 edited
     
    Simon H. I am getting good results even though the summer has been a bit dodgy (I will post them here soon, I promise). That is because the tracker can harvest the sunshine regardless of where it is in the sky. The static is less than normal though because it relies upon the sun putting in an appearance during a short 11.30 am to 4.30 pm window which has been harder to find.

    stwephendv's point is partly valid though. no one should install a system without mppt.
    • CommentAuthorscott
    • CommentTimeAug 12th 2009
     
    dual axis trackers offer the best outputs
    especially with uk limited sun conditions and short number of hours
    as used in most all big solar parks
    expensive to buy though
    can get them as small as to 300watts to take 1x300Wp modules or 2x150Wp
    • CommentAuthorstephendv
    • CommentTimeAug 13th 2009
     
    trackers have to compete with the falling price of PV panels. When panels were more expensive they made more sense, because you could maximise the output from your PV investment. Nowadays, it's usually cheaper to just buy more panels than it is to invest in trackers (and in their associated maintenance costs).
    The vast majority of solar parks are static, not tracked.
    • CommentAuthorTerry
    • CommentTimeAug 13th 2009
     
    Interesting point stephendv. Would it be of any use in a static setup to manually adjust the angle through the year - on frame mounted units - say once or twice a month or would it not be worth the effort of building the facility into the frame??
    •  
      CommentAuthorfostertom
    • CommentTimeAug 14th 2009
     
    On http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4420&page=1#Item_23 there's discussion about exactly why we should try to turn glass-fronted solar panels, PV or wet, perp to the sun's rays - there 2 separate reasons as far as I can see - and how much tolerance there is in that, for practical purposes.
    • CommentAuthorstephendv
    • CommentTimeAug 14th 2009
     
    Terry, I think for small systems that are already on frames it would be worthwhile. It will even be worthwhile to use DIY mechanical trackers that can be built cheaply. But when you start looking at the commercially available units they just don't make economic sense for most applications.
    • CommentAuthorGBP-Keith
    • CommentTimeAug 16th 2009
     
    This is a monitoring thread people so please move the discussion about 'tracking or not' to a new thread folks. Most of this will get deleted when I get around to bringing the stats up to date.
    • CommentAuthorSteveZ
    • CommentTimeMar 1st 2012 edited
     
    Even though this thread seems to have been inactive since 2009, the monitoring aspect is interesting. My system uses panel-based MPPT so it may be useful to look at it here.

    These are the results from the first full month (Feb 2012) of operation of my 4kWp PV array. It is arranged on two orientations. 3kW (12 panels) due East and 1kW (4 panels) due South, located just East of Bodmin Moor in Cornwall. I am interested to see how it compares with any similar 'conventional' inverter array as I have a system using on-panel Max Power Point Tracking, rather than that being done by the Inverter. In theory , it could give better power production, although there are slightly bigger losses in the circuitry.

    Is a total of 166kWh good, bad or indifferent for this array in the South West UK?

    BTW the difference in performance between the East and South sections is very marked at this time of year. As an example from one sunny day, East produced 2.1Kwh per 1kWp and the South 3.7Kwh per 1Kwp. I hope the sunrise moving towards the NE as the year progresses will bring the performance of the East section back to the theoretical 85% of a due South array.

    Date Energy (Wh)
    01/02/12 7880
    02/02/12 9473
    03/02/12 9480
    04/02/12 1034
    05/02/12 5654
    06/02/12 2664
    07/02/12 9419
    08/02/12 9973
    09/02/12 8983
    10/02/12 841
    11/02/12 8057
    12/02/12 3354
    13/02/12 4076
    14/02/12 4781
    15/02/12 2926
    16/02/12 5045
    17/02/12 4425
    18/02/12 3784
    19/02/12 8068
    20/02/12 7983
    21/02/12 5432
    22/02/12 1889
    23/02/12 4895
    24/02/12 3149
    25/02/12 5781
    26/02/12 10664
    27/02/12 3589
    28/02/12 2866
    29/02/12 10291
    Total Wh 166454
    Total kWh 166
    • CommentAuthorTriassic
    • CommentTimeMar 22nd 2012
     
    So from the results above I've concluded that as I have a large garden and a poorly orinated roof (for a fixed installation) that maybe I'd be better going down the tracker array route? I'm also thinking that if and when I move house I could pack the whole lot up a and take it with me?

    If I were to construct my own system how easy would it be? Doing a Google suggest that there is loads of kit available, but which is the best and most robust?
  17.  
    Posted By: SteveZIs a total of 166kWh good, bad or indifferent for this array in the South West UK?

    Can plug www.bdpv.com again? They provide a way of sharing PV production data and seeing others' production. The nearest site to you appears to be http://bdpv.com/fiche_utilisateur_en.php?util=iain

    When you compare two systems it automatically scales to kWh/kWp, which is v.convenient.

    To provide a direct answer: 166kWh seems good to me, but my 1.72kWp system only produced 68kWh in February ... at 55N.
    •  
      CommentAuthorSteamyTea
    • CommentTimeMar 22nd 2012
     
    Not one place in Cornwall :sad:

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