The set up

The set up
5.46mm jet delivering 0.68 l/s to the pelton which is rotating at 900 rpm and generating 135 watts into the grid.

Saturday, 14 March 2015

Fun with figures.

I never enjoyed maths at school but having lots of numbers to play around with, arising from keeping careful records of my turbine's output, is proving rather fun.

One of the devices which quietly keeps recording output day by day is a Sunny Beam. 



 It picks up a blue tooth signal from the Sunny Boy inverter (despite an intervening 450mm thick stone wall !) and logs the data in csv files. These can be downloaded from time to time and the data played around with in MS Excel.

I thought it would be interesting to see how energy output in this second "water year" of my turbine's operation compares with the first.  Here is the relevant information from the Sunny Beam displayed graphically:




Some points of interest:

  • peak energy output in the second year (blue line) is higher (18 kWh/day) than the first (17 kWh/day) because I got my calculations wrong in the first year and was not giving the turbine its full design flow of 3 lps that year.
  • In mid February 2014, there were strong winds and lots of rain across the UK and the winds caused very frequent voltage dips on the grid due to trees touching the lines.  Every time this happened the inverter disconnected from the grid and in consequence there was a noticeable loss in generating capacity.  Happily, in the intervening months, a great deal of line clearing has been done and this winter there has been no recurrence of this happening.
  • overall, in the present generating year (blue line), the total output is 65 kWh ahead of what it was last year for the same period. But this has been achieved at the 'cost' of having to change nozzles 23 times compared with 13 times last year.  It all depends on the rainfall.
Playing around with figures to bring them to life in this way has had the added benefit of teaching me how to use MS Excel.  Wish I'd known in working days what I now know about it.

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