The energy company (I use First Energy because they are large but with non-awful customer service) have just reduced my monthly payment for gas / elec to £65 from £80 of their own accord (which probably means a smaller reduction than is actually needed).
That means that within a year it has shrunk from £120 to £65, or £660 per year.
The only change we have made is to install a stonking 10kWP solar array in January, which is East/West and still rather shaded, and to switch suppliers - which reduced the payment from £120 to £80. Don't underestimate the power of switching and competition.
The house is a refurbed 4 bed chalet bungalow at just under 2000sqft with 2 people, which is generally good but we aren't obsessive.
I am sure that others have done as well or better, and we still can, and I wanted to record the numbers. Solar energy generated is going to be about 5500kWh (=another £600 in subsidy) for the year, which hints at how shaded our installation was and still is.
Ferdinand