I got a pleasant surprise from my $15,000 investment in solar last October. Power charges for the first quarter it has operated were $266 down from $887 the previous quarter or savings this quarter of $621. Naively assuming this trend will continue over the year (it might be more than this since the previous quarter is a low consumption quarter for my household) gives me annual savings of at least 4*$621 or $2484 per year which amounts to a tax free return of 17% on my investment. Interestingly a large part of the reduced bill was electricity sold back (at relatively low rates*) into the grid - around $367 in value for the quarter although our overall paid daily consumption fell considerably too - from an average of 28.5kWh last year to 20.3kWh in the last quarter. We are significant power suppliers!
I always assumed the solar vendors would exaggerate the economic case for their system. They did but only by a very small amount - in fact they were very accurate. If I continue with these savings this will be a great financial deal.
Why are households still buying power from the grid?
* We sold back into the grid 1501kWh and used 1889kWh. We sold back 80% of what we used.