Solar Generation Results to Sept 2013

I am updating the results of the solar PV system, below. It is now 3 years and a month since the system was installed [well, and a little bit of October too and the few days in August 2010]. This is giving me a good range to see what good and bad months are, as well as how the system is faring relative to what i hope was to be the rate of return.
First, I have my set of important variables : mean daily total kilowatts, mean kilowatts per watt installed, minimum and maximum output days. And the same is in dollars, as calculated from my data. However, what my datalogger calculates as output and revenue is less than what my Guelph Hydro meter shows. This is what I hear from others - what their system reports seems to be less than their utility's meter.  I haven't heard of anyone producing more than what their meter is reporting.

Variables	kW	Dollars
Mean	15.96	$12.80
Per 1 kW	3.26	$2.61
Min	0.05	$0.04
Max	35.44	$28.42
Sum - Daily kWhr	Years
Date	2010	2011	2012	2013	Total Result
Jan		169.7	255.8	242.6	668.2
Feb		275.0	322.5	213.8	811.3
Mar		560.8	569.3	499.5	1629.6
Apr		492.9	625.7	573.5	1692.2
May		534.3	757.8	767.9	2060.0
Jun		707.2	714.6	632.6	2054.4
Jul		769.0	762.4	693.0	2224.5
Aug	164.0	658.5	719.7	725.9	2268.1
Sep	438.0	528.0	599.6	572.8	2138.4
Oct	450.0	391.1	337.5	87.8	1266.4
Nov	355.4	316.3	286.3		958.0
Dec	78.2	219.8	144.3		442.4
Total Result	1485.6	5622.7	6095.6	5009.5	18213.4
as of:	2013-10-08

And you are likely asking, well, just how variable is it by month? Are the summer months consistently bright and the winter consistently dull? I know, you wanted to know the coefficient of variation, and now that i have 3 months (4 Septembers), i have done the calculations for you:

Month	CV
Jan	0.21
Feb	0.20
Mar	0.07
Apr	0.12
May	0.19
Jun	0.07
Jul	0.06
Aug	0.05
Sep	0.13
Oct	0.14
Nov	0.07
Dec	0.48

What it shows, for this limited dataset is that June, July, and August are fairly consistent between the years, with only 5 to 7% variation, whereas Jan, Feb, and esp Dec are quite variable between the years.