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Renewable Energy: Ronseal PV

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1 to 17 of 17

  1.  
    • CommentAuthorjms452
    • CommentTimeMay 30th 2012 edited
     
    I remember some old threads about fitters forgetting to connect a string etc on PV installs and didn't fancy waiting year/few months to check performance.

    So using pvgis (thanks Damon) I calculated the clear sky irradiance of the two 45 degree inclination arrays 1.75kW SSE(-11) and 2.25kW WSW (-79) for May.

    The pvgis fixed plane clear sky irradiance is multiplied by panel efficiency (15.4%) x panel area (1.6m2) x no of panels (16) x non-panel system efficiency (90%). The the two aspects summed for each time interval.

    This only holds for a perfect cloud free days so I was rather chuffed when day 1 was the start of our mini heat wave!

    The only fudge factor is the non-panel system efficiency (inverter + wires + panels getting hot + etc) which pvgis suggests as 86% but I got a better fit at 90%.

    So it seems at a first (and arguably second) order pvgis is a very good predictor of clear sky irradiance and that my array(s) 'does what it said on the tin'.

    Now it just 'weather' to investigate - I think I should hold off for a bit before making any impressive claims for annual yield based on the 5 days since install..
    • CommentAuthorjms452
    • CommentTimeMay 30th 2012
     
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 30th 2012
     
    No idea where you are, but I would expect 95% of the time your output will be between Red and the Green lines.
      Cloud Variation.jpg
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 30th 2012 edited
     
    Interesting that there is a small dip at 9AM on the prediction and you have a dip in performance until then. There is nothing to read into that at all, I suspect that the small dip is either a rounding error if they are using some random numbers to mimic cloud cover or a van parked by the light meter if they are not.
    •  
      CommentAuthorDamonHD
    • CommentTimeMay 30th 2012
     
    Could be allowance for horizon effects.

    I get some very early morning shading even now from a tree a considerable distance to the north east of us.

    Rgds

    Damon
    • CommentAuthorjms452
    • CommentTimeMay 30th 2012 edited
     
    The dip at about 9:30 predicted is probably just excell when the gradient of the line changes from diffuse to direct sunlight.

    The dip on actual is partly due to a big tree about 50m East from us and partly due to a slight haze that morning - on subsequent mornings it moved up close to predicted at about 8:30.

    In general very pleased both with the direct sunlight performance and the amount of power we generate even when its cloudy. i.e. in todays thunder storm we had ~100W as we do at the moment (wrote at 8:30pm -dusk approaching) !
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 30th 2012
     
    Diffused light can be quite deceptive. Sometimes it is possible to get more power by pointing a panel directly upwards (how solar data is collected) as then, regardless of the time of year, as soon as the sun is up, some light is being collected.
    Keep wanting to test this more to find out how much difference it makes over a year.
    • CommentAuthorjms452
    • CommentTimeJun 17th 2013
     
    The PV has been up for a year now (and when searching through old threads I always wonder what happened in the end) so I thought I'd post the production over the past year.

    Predicted (by the installers): 3152kwH
    Actual: 3510kwH

    :bigsmile:
    •  
      CommentAuthorSteamyTea
    • CommentTimeJun 18th 2013
     
    358 kWh extra is not to be sniffed at.
    Do you have the split on the two strings/arrays?
    • CommentAuthorbillt
    • CommentTimeJun 18th 2013
     
    MCS installers have to use SAP for the predicted output in their quote, which is (rightly) very conservative.

    Quoted SAP production for my system was 3026 kWhr P.A., PVGIS prediction was 3450 or 3710 depending on which model was chosen. Actual production is 7043 kWhr over 2 years, 3520 P.A., 16% more than the SAP estimate.
    • CommentAuthorjms452
    • CommentTimeJun 18th 2013
     
    Posted By: SteamyTeaDo you have the split on the two strings/arrays?


    Yes using a 2 string independently MPPTed inverter (SMA 3600TL) one string for the 1.75kW SSE and the other for the 2.25kW WSW.
    •  
      CommentAuthorSteamyTea
    • CommentTimeJun 18th 2013
     
    You have bluetooth on that, do you look at the daily files?
    • CommentAuthorjms452
    • CommentTimeJun 19th 2013
     
    Yes but the installer threw in a Sunny beam too so that's what we tend to look at.
  14.  
    Is the SMA3600TL set on optitract global peak ? might counteract slight morning shading
    "OptiTrac Global Peak is an extension of the proven OptiTrac yield optimization function.
    OptiTrac Global Peak improves the yield of the PV plant for partially shadowed PV modules. Detailed
    information on this topic is available in the technical information "Shade Management" in the
    download area at www.SMA.de/en."
    • CommentAuthorjms452
    • CommentTimeJun 21st 2013
     
    Posted By: jamesingramIs the SMA3600TL set on optitract global peak


    Its the 3600TL-20 and the data sheet claims 'Shade management with OptiTrac Global Peak'.

    Is this something that I can bluetooth into the inverter and check it is enabled?

    I'll have a look but the installers seemed pretty clued up...
    •  
      CommentAuthorSteamyTea
    • CommentTimeJun 21st 2013
     
    Posted By: jms452
    Is this something that I can bluetooth into the inverter and check it is enabled?
    Yes it is.
    I seem to remember chatting to some about OptiTrack and he though that it took longer to 'sort itself out' and that could cost you some power generation.
    Never got to check it out, so only third hand information.
  17.  
    Yes , can be switched on via Bluetooth using sunny explorer
    Will be on settings list, , I think you'll need to log on as installer, default password is shown on log on screen
    Click on my name for email, send one over and I'll send SMA pdf on multi function relay and optitract ( not a great deal of info in it though)

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