PV Generation to Mid-April 2013

I'm posting my latest data updates here. The April 2013 is only to the 15th of the month hence the 268 kWhr. February, March, and even the first half of April are not so good for production, but then Jan-April 2012 were exceptionally beautiful conditions.
I also have posted immediately below my basic stats of kWhr and Dollars per day, averaged over the 2 3/4 year lifetime of the system. Overall my most interesting stats are 3.05 kWhr/kW/day and $2.44/kW/day. These numbers would be helpful for anyone to help estimate their expected revenues. Of course every system is different, mine is facing south east, etc. A more representative statistic will be from August 2013 when we will have the anniversary date. The 3.05 and $2.44 will increase a bit over the summer because we get most of our solar generation happening then, and the stats below don't include the 2013 summer data of course.

Variables	kW	Dollars
Mean	14.93	$11.98
Per 1 kW	3.05	$2.44
Min	0.05	$0.04
Max	35.13	$28.17
Sum - Daily kWhr	Years
Date	2010	2011	2012	2013	Total Result
Jan		170	256	243	668
Feb		275	323	214	811
Mar		561	569	499	1630
Apr		493	626	268	1387
May		534	758		1292
Jun		707	715		1422
Jul		769	762		1531
Aug	164	658	720		1542
Sep	438	528	600		1566
Oct	450	391	338		1179
Nov	355	316	286		958
Dec	78	220	144		442
Total Result	1486	5623	6096	1224	14428
as of:	2013-04-16

PV Revenue to Dec 2012

December was pretty grey here and my solar panel revenue reflect that, see below. However, note the difference between Dec 2010 and Dec 2012 - nearly half the production in '10 and I attribute this to snow cover. It is always hard to assess the impact of snow on panels because it is hard to have a "control" that is snow-free and a "normal" array of panels that are permitted to accumulate snow. It is ether too expensive to set up such a study for a home owner and heck - if you could clear off the snow easily and safely then you'd do it! It is not really a research question anyways, it is a curiosity that has financial implications  And perhaps design considerations too.
One interesting thing I was asked the other day was about the way snow slides off, safety, and panel layout. When I had my panels installed I spoke to my installer where the bottom panel should be placed:

• bottom of panel is above shingles - some rain will fall on a concentrated location on the shingles and could cause excessive wear. Snow can slide off and can cause ice damming.
• bottom of panel is above eavestrough - rain drops into eavestrough. Ice and snow can slide off and accumlate in eavestrough potentially causing high load on eavestrough and/or causing ice damming that may harm shingles.
• bottom of panel extends beyond the eavestrough - show and rain are shed directly below, potentially causing safety issues. 

I opted to have my panels end directly over my eavestrough. I can't say if ice damming has been a significant issue but I don't think so. Only under the most intense thunder storms has rain run off the panels and gone over the eavestrough. Some precip may shoot down the other two rows of panels down onto the lower row and caused a concentration of water on the lower panels, but the small gap between the panel rows is sufficient to minimise that. Overall, I don't think it is a huge issue. However, just like a metal roof on a shed or barn, one must be careful about the risks of snow and ice sliding off the structure and falling on people below.
Table 1. Sum of daily revenue by month.

Sum - Revenue, daily	Years
Date	2010	2011	2012	2013	Total Result
Jan		$136.10	$205.18	$67.37	$408.66
Feb		$220.57	$258.66		$479.22
Mar		$449.77	$456.57		$906.34
Apr		$395.30	$501.84		$897.14
May		$428.51	$607.72		$1,036.24
Jun		$567.19	$573.10		$1,140.30
Jul		$616.75	$611.45		$1,228.19
Aug	$131.53	$528.09	$577.23		$1,236.85
Sep	$351.28	$423.49	$480.85		$1,255.62
Oct	$360.90	$313.65	$270.70		$945.25
Nov	$285.03	$253.69	$229.61		$768.33
Dec	$62.74	$176.31	$115.73		$354.79
Total Result	$1,191.47	$4,509.43	$4,888.65	$67.37	$10,656.92
as of:	2013-01-13

Table 2. Sum of daily power generation by month.

Sum - Daily kWhr	Years
Date	2010	2011	2012	2013	Total Result
Jan		170	256	84	510
Feb		275	323		598
Mar		561	569		1130
Apr		493	626		1119
May		534	758		1292
Jun		707	715		1422
Jul		769	762		1531
Aug	164	658	720		1542
Sep	438	528	600		1566
Oct	450	391	338		1179
Nov	355	316	286		958
Dec	78	220	144		442
Total Result	1486	5623	6096	84	13288
as of:	2013-01-13

Note: August 2010 and January 2013 are partial months.
It is nice to see that we have 4 months now with 3 years of full data measurements. It shows the considerable variability between the months.

Charting out the Generation, Revenue, Expense of our PV System

I've cumulatively plotted out the revenue my PV system has generated over time as well as what I've paid on our load. I've also plotted out the microFIT payments I've received from Guelph Hydro. Note the following:

• revenue (blue) increases relatively over the spring and summer months and slows down over the winter
• our revenue was initaially greater than out payments, then over the first winter revenue was lower than the payments. The revenue overtook the loan payments in June 2011 and has been a net income ever since
• our net earnings to date have been approximately $8500-$7500=$1000
• the microFIT payments are lagging my loan payments - I've needed to keep a float in my account to cover the delay of payments
• the time period between microFIT payments from Guelph Hydro is rather variable. The last payment in particular was delayed quite a bit and I had to put extra money in my account to cover the automatic withdrawal of the loan payments. Guelph Hydro told me they are implementing a new billing and payment system that will automate their payments. They told me they had now over 100 microFIT contracts connected in Guelph. It also tells me that Guelph Hydro is much more consistent in sending bills to me than wanting to pay me.

Revenue generated, loan expenses, and microFIT payments

Plotting Revenue Up To 14 May 2012

A quick chart to show the revenue generated from our system. The orange line is our daily loan payment amount. We don't pay daily of course, but I plot the line for illustrative purposes.

Figure 1. Daily revenue to 14 May 2012.

April 2011 Revenue and Cost Results

The chart below shows an update of our daily revenue and loan. The horizontal line at $10.70 is our loan payment [we pay biweekly]. The individual points are the daily revenue [we get paid by Guelph Hydro bi-monthly].
My observations for April, or at least to 28 April, shows several things :

• a large scatter above and below our loan payment line, but the days where it is below $10,70 is not so dismally low as December and January
• the brightest day of April was the 15th which rivals the bright days in March. Even though the panels would have been a little warmer than in March, and the reflectance from the ground lower since the snow has melted, perhaps it is the longer day and higher sun that yielded more energy
• late April has been very cloudy and dismal here in Guelph, so revenue is on average lower than our costs
• final observation is that Chris Duke looks out his office window in April a lot and wishes for sunnier days. This has been wetter and cloudier April then other years [even the amount of fields with the corn sown is behind normal years]