#1 May 8, 2014 11:02:00

SunnySouthwell
Registered: 2014-01-22
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Solar iBoost Statistics


Is anyone with an iBoost doing anything with the statistics it reports ?  Every day I manually enter into a spreadsheet the energy diverted for yesterday, the last 7 days, the last 28 days and total.  The spreadsheet also gets the previous day's generation number downloaded via my Sunny Beam so that I can produce statistics and charts.


But the spreadsheet also calculates last 7 and last 28 numbers from the individual days' results and I've noticed that there's a consistent mismatch.  The iBoost always reports the 7 day number 0.02 higher than the spreadsheet, and always reports the 28 day number 0.9 higher than the spreadsheet.


The ‘total’ numbers have a difference of 0.96 but I only started recording that today so have no history to compare yet.


Is anyone seeing the same oddity ?


Steve Webb


URN 6390,  Southwell








Edited SunnySouthwell (May 8, 2014 11:02:00)

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#2 May 10, 2014 14:31:00

psglondon
Registered: 2012-09-04
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Solar iBoost Statistics


hi,


I think it is your spreadsheet calc, you may find that it is ‘rounding’ off the numbers, set the decimal for 4 or 6 decimal points, ie, 11.225588, then it may bring it into line,


I have had simular when using small numbers and adding up,


URN 





Edited psglondon (May 10, 2014 14:31:00)

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#3 May 11, 2014 09:07:00

SunnySouthwell
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Solar iBoost Statistics


'fraid not.  I set all of my spreadsheet cells to 4 decimal places and now I get consistent differences of 0.0200 and  0.9000, the same values as before but with more trailing zeroes.  


If there are any rounding errors, and I suspect that there are, it seems more likely that they are in the iBoost.


Steve Webb  


URN 6390  Southwell








Edited SunnySouthwell (May 11, 2014 09:07:00)

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#4 May 11, 2014 17:34:00

SteveRogers
Registered: 2011-12-08
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Solar iBoost Statistics


I've only recorded the daily amounts diverted by the iBoost.  Since it was installed on 4 March (69 days) these daily numbers total 135.19 kWh whereas the iBoost indicates 135.81 kWh.  I can't be sure that I've got all the iBoost daily figures correct as I have been away for a few days and had to interpolate guesses from the 7 day total for that period.


I plotted the iBoost figures against the total production - the graph is in my gallery here:  http://www.microgen-database.org.uk/gallery/pv-system-around-dormer-window/balcony/iboost-results


I don't think this graph tells me much as it will depend, not just on total production, but on how much hot water has been used, when it was used, how much production was over the 200W threshold, etc.  Too many variables …   There was also the problem with the cable clamp discussed elsewhere in this forum.


The daily numbers vary from zero to 3.86 kWh (or 0% to 38% of my daily production).  It looks like 2-4 kWh is enough to give us a full tank of hot water, though we still have the central heating on in the evening for 1/2 hour to top this up as the weather here has been inclement this month


Steve


URN 215 North Yorkshire 3.96 kWp, S facing, 40 deg tilt, minor shading





Edited SteveRogers (May 11, 2014 17:34:00)

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#5 May 12, 2014 15:59:00

SunnySouthwell
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Solar iBoost Statistics


I also plot my daily diverted power against generated power, see www.webbsfamily.co.uk/iBoost for the latest chart, (which includes a line where I've eyeballed an approximation to a best-fit).


Up to 3 units generated we get nothing diverted, over 12 units enough seems to be diverted to trigger the immersion thermostat, and between 3 and 12 there's a very approximately linear relationship.


As you said, from day to day there are so many variables that these charts are interesting, but you couldn't make any predictions from them.  Although I suppose that you might be warned of a problem with the system if you got points way out of line.


Steve


URN 6390  Southwell





Edited SunnySouthwell (May 12, 2014 15:59:00)

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