I have now collected\u00a0a year’s worth of data on how my modest, 1.68kW peak PV system has performed over the last twelve months, and it makes for interesting reading.<\/p>\n
Over the period October 2011 through to the\u00a0end\u00a0of September 2012, I generated a total of\u00a01075 kWhs.\u00a0 Across that same period I consumed a total of 2218 kWhs of electricity\u00a0(a large jump upwards\u00a0from years gone by and I’m at a bit of a loss to explain where that increase has occurred – but that’s for\u00a0another blog post).\u00a0 So in total\u00a0I have generated a little less than half my yearly demand.<\/p>\n
My new backstop meter, installed at the end of September 2011,\u00a0informs me that my total net electricity demand over the last 12 months, that is\u00a0from the grid,\u00a0totaled 1430 kWhs.<\/p>\n
Hence that in turn\u00a0that\u00a0tells me that my PV system has fulfilled approx 35% of my total electricity\u00a0use over that time period;\u00a0not bad for a small system!<\/p>\n
Even more encouragingly, it also shows\u00a0that I have managed to locally\u00a0utilise around 75% of\u00a0my total PV generating capacity.\u00a0 Only 26.5% was exported out to the grid.\u00a0 We have been changing our habits and behaviours to maximise usage and\u00a0also, as I work\u00a0from home for a significant proportion of the day, I am able to take advantage of sunny afternoons to put the washing on, and to cook meals, but regardless I’m particularly proud of this statistic.<\/p>\n
When we come to payback times, the data isn’t so encouraging.\u00a0 An approximate 1000 kWh annual output has garnered me around \u00a3450 in FiT payments this year, including the extra 3pence for 50% of the\u00a0generating capacity\u00a0that is assumed is put back\u00a0into the grid (for me that is generous as I’m only putting back 25%!).<\/p>\n
The 788 kWh of free PV\u00a0electricity\u00a0I have used has saved me around \u00a3100 in annual electricity charges.<\/p>\n
Put together that adds up to a total of \u00a3550 savings per annum.\u00a0 On a \u00a38000 original\u00a0outlay, it will take around 15 years to pay back the original capital cost.\u00a0 Far greater than the sub 10 year claims that abound in the industry.\u00a0 This doesn’t overly concern me, as there is another 10 years of useful service out of the system after all original costs are paid off, and the point of having the system wasn’t just to get a quick payback.\u00a0 But it is an interesting finding, and\u00a0I would very interested in hearing from other PV owners to see if I am typical or whether my smaller than average system, and the fact I do not\u00a0have a perfectly due south aspect has reduced my generating capacity to a significant extent?<\/p>\n
So, please get in touch if you have an interesting PV generation story to tell.\u00a0 is your system over- or under- performing? and if so, why do you think that is?<\/p>\n
Other related blogposts on PV generation and ownership by paula owen consulting:<\/p>\n
Being a PV generator: Lessons I have learnt Part 1<\/span><\/span><\/a><\/span><\/span><\/p>\n Being a PV generator: Lesson learnt Part 2<\/span><\/a><\/span><\/span><\/p>\n