Production Update to March 2016

Time for me to post a new update of the production from my solar array. In October 2013 I installed some new equipment, including Tigo Energy optimisers [www.tigoenergy.com]. I was not anticipating a significant increase in the overall array efficiency because the array is not facing any shading. It should increase the output and efficiency during the winter when there is partial coverage due to snow and ice.
Table below shows the production to date as well as the efficiencies for each month.

Updated:	04/02/16
		Years
Date	Data	2010	2011	2012	2013	2014	2015	2016	Total Result
Jan	Sum - Daily kWhr		170	256	243	216	281	210	1374
	Average - Efficiency [kWhr/kW]		0.9	1.3	1.2	1.1	1.4	1.1	1.2
Feb	Sum - Daily kWhr		275	323	214	197	333	312	1652
	Average - Efficiency [kWhr/kW]		1.5	1.7	1.2	1.1	1.9	1.7	1.5
Mar	Sum - Daily kWhr		561	569	499	577	663	483	3352
	Average - Efficiency [kWhr/kW]		2.8	2.9	2.5	2.9	3.3	2.4	2.8
Apr	Sum - Daily kWhr		493	626	574	615	656		2962
	Average - Efficiency [kWhr/kW]		2.6	3.3	3.0	3.2	3.4		3.1
May	Sum - Daily kWhr		534	758	768	699	745		3504
	Average - Efficiency [kWhr/kW]		2.7	3.8	3.9	3.5	3.8		3.5
Jun	Sum - Daily kWhr		707	715	633	757	687		3499
	Average - Efficiency [kWhr/kW]		3.7	3.7	3.3	3.9	3.6		3.6
Jul	Sum - Daily kWhr		769	762	693	735	821		3780
	Average - Efficiency [kWhr/kW]		3.9	3.8	3.5	3.7	4.1		3.8
Aug	Sum - Daily kWhr	164	658	720	711	694	693		3640
	Average - Efficiency [kWhr/kW]	3.2	3.3	3.6	3.7	3.5	3.5		3.5
Sep	Sum - Daily kWhr	438	528	600		626	625		2817
	Average - Efficiency [kWhr/kW]	2.3	2.8	3.1		3.3	3.3		2.9
Oct	Sum - Daily kWhr	450	391	338	79	381	455		2093
	Average - Efficiency [kWhr/kW]	2.3	1.9	1.7	1.8	1.9	2.3		2.0
Nov	Sum - Daily kWhr	355	316	286	296	177	334		1765
	Average - Efficiency [kWhr/kW]	1.9	1.6	1.5	1.5	0.9	1.7		1.5
Dec	Sum - Daily kWhr	78	220	144	119	169	148		877
	Average - Efficiency [kWhr/kW]	0.4	1.1	0.7	0.6	0.8	0.7		0.7
Total Sum - Daily kWhr		1486	5623	6096	4828	5841	6439	1005	31317
Total Average - Efficiency [kWhr/kW]		1.8	2.4	2.6	2.4	2.5	2.8	1.7	2.5

You'll see that of course the efficiency is different for each month from winter to summer to winter again - there is much less sun energy coming in so the panels generate less. The same pattern for total energy output. The summation in the right column doesn't mean too much given that part way through October 2013 the equipment changed. The sum and averages at the bottom are interesting. Disregard 2013 again due to partial data and a change in the equipment. 

Comparing 2011 and 2012 with 2014 and 2015 we see the following:

• lowest output was 2011 [range between 2014-2011 = 218 kWhr]
• highest was 2015 [range between 2015-2012 = 343 kWhr]
• average efficiency 2011-2012 = 2.5, post upgrade = 2.65]

These statistics, if anything, show that there is quite a lot of annual and intra-annual variability in energy production. There was 600 kWhr difference between 2014 and 2015, or about 10%. 

So? Was the equipment upgrades worth it? Let's look at more statistics.

Variables kWhr Dollars

Mean 15.90 $13.03

Mean post upgrade 15.50 $12.43

Per 1 kW 3.24 $2.66

Per 1 kW post upgrade 2.42 $1.94

Min 0.05 $0.04

Min post upgrade 0.08 $0.07

Max 35.44 $28.42

Max post upgrade 36.49 $29.26

Pre and post upgrade, the data show an underwhelming result despite an extra 1.5 kW of capacity:

• mean kWhr was actually higher before the upgrade
• efficiency was lower by 0.8 kWhr/kW installed post upgrade
• maximum daily output on the best day pre and post upgrade increased from 35.4 to 36.5 kWhr

The maximum daily output and other values of course can vary by year, but really, the max daily output should be at least 1.5 kW x 3 hours = 4.5 kWhr. I'll state this because I think that over any given 2 year period, there will be at least one amazing, sunny, clear, long, cold day.

I shall investigate this much more indepth using RETScreen soon and share these results with you.

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

Some Basic Parameters of the PV System to Date

There are some handy parameters that can be used to estimate the power or revenue generation of a PV system. Often people will take the kW of the system and multiply it by the expected parameter to get expected value such as kW hours per year or dollars per year. These numbers are relatively easy to calculate. Ideally people are using the most realistic values possible if they want to estimate their expected outcome.

An example is, how many kilowatt hours should I generate from my 5 kW system on my roof?

First, here are my parameters for our 4.9 kW DC system [5 kW string inverter]:

Variables	kW	Dollars
Mean [4.9 kW]	15.81	$12.68
Per [1 kW]	3.23	$2.59
Min [4.9 kW]	0.05	$0.04
Max [4.9 kW]	35.13	$28.17

In this case, applying my parameters to a hypothetical 5 kW DC system, we could estimate mean daily kW production over the year to be 5 kW * 3.23 kW per kW = 16.15 kW per day. Multiply that your FIT contract price and this would be your daily income averaged over the year. 

You can use the values above to estimate your highest and lowest income as $28.17 / 4.9 * your DC kW.

Oh, and you can see that you'll have some bad days too - $0.04 / 4.9 kW will give you $0.01/kW on dark snowy, snow-covered panel days. 

Little Snow Means Better Solar Production in 2011-2012

Spring is already here but our 2011-2012 winter ended a long time ago. There has been very little snow - I didn't have to shovel much since Christmas. The sky seems to have been clearer too and this has enabled our solar array to generate more power than last winter. It means a lot too, financially. Last August was our 1 year anniversary and on a $30k investment after 10-year loan payments, we netted $460 - not a great return on investment so hopefully 2012 will be better. So far, so good. Here is our kWhr generated by month in Table 1.

Sum - Daily kWhr	Years
Date	2010	2011	2012	Total Result
Jan		169.7	255.8	425.5
Feb		275.0	322.5	597.5
Mar		560.8		560.8
Apr		492.9		492.9
May		534.3		534.3
Jun		707.2		707.2
Jul		769.0		769.0
Aug	164.0	658.5		822.5
Sep	438.0	528.0		966.0
Oct	450.0	391.1		841.1
Nov	355.4	316.3		671.7
Dec	78.2	219.8		298.1
Total Result	1485.6	5622.7	578.4	7686.7

If I use Dec-Feb to define winter, then we yielded 523 kW in 2010-2011 and this year 798 kW. That is a 275 kW difference or $220.55 difference in revenue. We'll see what this March brings to be able to compare two full winters. December 2010 and 2011 were especially different because Dec '10 was dark, dreery, and frequent intermittent snow that accumulated on the panels and seldom fully melted off or slid off.
The system didn't get connected until 25 August, so ignoring that we can see that most months are better than the year before, other than Oct and Nov 2011. We had a "dark" fall, but otherwise, I see it is all going well.
As you may read in this blog, I focus on the numbers, kW, dollars, and cents of our solar system. I am interested in these results today as it shows that you can't use a single year to determine if production data. Or any coefficients either. In an earlier posting I calculated the typical coefficients people use to estimate the power generation for our first year. I look forward to calculating this year's coefficients, plus to calculate the values for the duration of the system - that way we'll get the general values to expect for a multi-year estimation of coefficients.
So far, so good.
Oh, a little note about how I analyse these data. I use OpenOffice Calc to store and analyse the data. I use the Data Pilot tool [Pivot Tables in Excel] to summarize the data very quickly and easily.