daylight according to charts

garynappi
garynappi Registered Users Posts: 120 ✭✭
in General Solar Power Topics #1
I installed my 100 watt panel 11 feet from ground facing due south. I have been charting when my yard lights come on and turn off and time to turn on as well as when the panel escapes the tree shadow to the east and goes behind the tree shadow in the west.

So far despite the tree shading the panel, it's getting solid daylight and charging the battery (14.8v in east am sun to 12.5 v turn off entering the tree shade) just under 7 hours. 

This weekend I am trimming both trees and expect a lot more charge hours.

So my question is... why the disparity between the available daylight hours and my recorded?

Does it have to do with max charge current or something else I don't get from the chart?

My panel is at 47 deg. still a bit low for late summer but high for winter.

The solar insulation map states a high of 6.5 hours but despite my shading issue I am getting nearly 7 hours.
 
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
    The solar figures are averages based on data collected over many years, a single sample may be higher or lower on a particular day depending on cloud cover etcetera, making an average more accurate. Despite this, the figures are just a guide to aid in design, there are too many variables to consider and a single day, week or year may differ significantly.

    More importantly the peak hours are where, on a fixed array, panels produce the most output and this window is significantly less than the daylight hours. Early morning and late afternoon sun will only produce a fraction of the maximum, tracking will improve output at the expense of complexity.  For a fixed array the angle chosen should be for when the system needs the most energy and this differs depending on personal useage, a cabin used only in summer for example may want to position for optimal summer production, so it's not one size fits all so to speak. 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #3
    A solar insolation map is likely showing the average number of full sun equivalent hours, not daylight hours or hours there's some pv production.

    First, there are a few hours around solar noon when the sun might provide something like 1000w/sq.m pv is rated at. Outside those hours, and in winter, the sun is less strong.  It might take (eg) 10hrs to get 6.5hrs of full sun equivalent. 

    Second, insolation is an average of (eg) 20yrs data, including lousy weather etc.  Some years will be better, some worse.


    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
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
    Google “Sun roof” (I think that is what it is called) gives a pretty good real world analysis on every roof in the neighborhoods they have covered.  

    https://www.google.com/get/sunroof

    don’t know if they cover Canada yet however
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  • garynappi
    garynappi Registered Users Posts: 120 ✭✭
    #5
    icarus said:
    Google “Sun roof” (I think that is what it is called) gives a pretty good real world analysis on every roof in the neighborhoods they have covered.  

    https://www.google.com/get/sunroof

    don’t know if they cover Canada yet however
    That's an interesting website thanks.
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  • garynappi
    garynappi Registered Users Posts: 120 ✭✭
    #6
    Estragon said:
    A solar insolation map is likely showing the average number of full sun equivalent hours, not daylight hours or hours there's some pv production.

    First, there are a few hours around solar noon when the sun might provide something like 1000w/sq.m pv is rated at. Outside those hours, and in winter, the sun is less strong.  It might take (eg) 10hrs to get 6.5hrs of full sun equivalent. 

    Second, insolation is an average of (eg) 20yrs data, including lousy weather etc.  Some years will be better, some worse.


    The data compiled over many years sort of makes sense, TY
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