Watts going down

Recently I received an updated set of power consumption figures from my electricity supplier and I was interested to see by how much the solar PV system had reduced my imported electricity levels. Based on the figures supplied (which are far from ideal, being spaced at 80 day intervals) I got the chart below.

It's not a perfect way to work, but it does go some way to show the impact of the system. At the moment we are relatively high power users - part of this is the garden pond which can use 500 watts of continuous power in the summer (less in winter when some of the devices can be switched off) plus the air-conditioner in the summer can get the meter whizzing round too. (Although the latter has seen much less usage this year).

Based on a few rough calculations this would seem that I'm using about 7 kWh less of power a day since the panels went in - which seems a little high since this would suggest only 20% of power was being exported. I suspect we're being a little more economical than before and running the dishwasher and laundry during peak sunny times probably helps make the best of the system, hence not all of the drop is from the panels, some of it may just be our changing behavior.

7 kWh a day are equivalent to about £25 a month off the electricity bill, which is not to be sniffed out - the equivalent of £300 a year of additional return on the system (in addition to FIT and export payments). Not bad at all.