Most of the headings should be self explanatory.
Column B is the total power output on the day in question. Column C is the total
power output since installation date. D is the number of kWh needed to fulfill
the annual (supplier provided) prediction and E is the profit or loss
on that prediction.
F is the average daily output for the month, G is the accumulated total for the
month. H is power generated against the prediction for the
month expressed as a percentage.
I is the cumulative annual achieved output as a percentage of the annual
predicted output.
K and K are calculated from the current Feed in Tariff plus the deemed 50% export.
Columns D, F, G and H are reset on the 1st day of each month to reflect the new
monthly prediction as necessary.
The interest and profit columns compare the FiT plus 50% deemed exported with the
daily compounded interest which may have been gained had the money been invested
and the interest taxed. 3% is chosen because that is what I was getting from the
instant access account from which the money was taken. The rate will be adjusted
if the instant rates I might have earned are changed. The higher rates are given
solely for illustrative purposes. My inclination would not be to put money into
a five year bond at the present time and so for me the figures are academic but
may be of interest to others. If long term bond rates are changed the figures
used here will not be, at least not in the first five years as that would be unrealistic.
Column O can only be regarded as a guess at this early stage of the systems
life. It is my savings on the electricity bill at my current tariff if I use
half the generated power. In Winter with a pond pump and computer gear running
constantly that may be possible but in Summer could be optimistic. An adjustment
may be made in the light of experience.
I hope the spreadsheets will be of assistance to anyone contemplating a similar
installation. Feel free to modify if you wish.
2017.
2016.
2015.
2014.
2013.
2012.
2011.