6.48 mm diameter nozzle delivering 0.91 l/s to the runner which is rotating at 1084 rpm and generating 225 watts into the grid at an overall efficiency of 47%.

Tuesday 1 October 2024

Year end results for 2023-24 water year.

The year to September 30th has seen the most generation in the eleven years my Powerspout has been running. The total energy generated was 5254 kWh.

Understanding that this figure is really quite good for a small turbine is best captured by considering what is called capacity factor.

Capacity factor is the energy generated in a year divided by the energy that could have been generated if the turbine had run everyday for 365 days at the rating specified in its technical specification.

The rating specified for my turbine is 750 watts, which means the maximum power it is meant to be able to produce is 750 W. And using this figure, the maximum energy that could be produced in a year is 6,570 kWh (calc: 0.75 x 24 x 365).

So the capacity factor for the 2023-24 water year turns out to be near enough 80% (calc: 5254 / 6570 = 0.799).

But there is a slight deception in this figure. And this is because the maximum power my Powerspout can actually produce is more than 750 W, and this is evident in the first of the plots below.

There is a reason why there is this deception: the figure of 750 W had to be specified before the turbine had even been commissioned and was a figure derived purely from theoretical calculation. This theoretical calculation had to make assumptions about a lot of things such as friction loss in the pipeline, the efficiency of the 3 phase alternator, the efficiency of the dc/ac grid-tied inverter, ...and many more factors, - all of which were little more than educated guesses.

When the turbine actually got to run, many of the guesses turned out to be on the pessimistic side and the turbine actually was found to produce nearer 800 W at full flow, and even 900 W if slightly more water than the specified maximum flow of 3 l/s was used.

So the 80% capacity factor figure is inflated, and if the true maximum power of 900 W is used to calculate it, the figure drops to 66%.  But since officially my turbine is rated at 750 W, that's the figure I'm going to continue to use for my capacity factor calculations. But I will point out that in the interests of 'honesty and transparency' you'll notice that I do say in the Scheme Details section in this blog where each year's capacity factor is given, that the figures are "taking as datum DNC 750 W" (DNC = Declared Net Capacity).

For those who like to appreciate how a small scale hydro works out in the real world, here are the figures for this past year's generation. The year 2023-24 is the black plot line, and previous years are coloured lines:










































Monday 22 April 2024

Powerspout+Solar+Battery= the perfect combination.















I've posted a video on Youtube for those who want to know the 'length and breadth' of my home's energy system.

You can find it at https://www.youtube.com/watch?v=-rmYOUQAVTk 

You'll need 20 minutes to view it all, and it comes in HD.

I'll add a link to the side bar of this blog for future access.

------------------------------------

Addendum: added 23 April 2024

In response to people wanting to know the cost of the battery storage scheme, below is a breakdown.

The costs given include VAT at 20% (the installation was done before the UK Government decided to exempt retrofitted battery storage schemes from the 20% rate).



Sunday 4 February 2024

Benefitting from Battery storage

There can be no better way of communicating the benefit of having battery storage than publishing the graph below.

It records the energy my house has taken from the grid each month, starting at January 2023 and ending January 2024*; the battery storage was commissioned on 1st November 2023.

The step-down in grid consumption from November is quite remarkable, - more than I ever expected.

The data for the graph is reliable; the figures come from the meter readings sent to OVO, the electricity utility who sell grid energy to me.

I look forward now to seeing how this graph pans out over a full year; the three months in which battery storage has so far been contributing, have been months when the Powerspout has generated at its maximum and there has been little input from solar; later in the year, the mix will change, - and therein lies my interest to see how the full year looks.

* I will update the graph each month after January 2024, and do this for 1 year, to give the latest information.






Addendum added 15 April 2024

How the above graph 'pans out over a full year' will depend on how total energy generation from solar and hydro changes in the course of a year.
The pattern of how it changes is seen in the graph below.
The graph shows the total kWh generated each day from hydro and solar, between October of one year and September of the next.
The blue spiky line is the kWh generated each day.
The value of the data point for each day is the 8 year average of the energy generated on that day.
The red polynomial line is the 'best fit line' for the blue line.
It will be seen that maximum generation is from mid February to June, and in this period the graph above can be expected to show the least energy taken from the grid.
Conversely, least generation happens in September / October, and in those months grid supplied energy is likely to be needed.