Code Violations For Residential PV Systems

I found an interesting resource for solar PV articles about installations. Renewable Associates has some good publications online. I think it is an American resource, but the lessons are useful in this article about building and electrical code violations. http://renewableassociates.com/wordpress/wp-content/uploads/2011/02/Common-Code-Violations-Residential-PV-Systems.pdf

PV Results to September 2016

This summer was very warm and clear with very little rain. We had a great solar summer! Looking at the 2016 column, the solar panel productivity was very high, much higher than any other comparable month. However, this is also influenced by the re-wiring that our solar contractor did on 19 April. If you look at the table below, the productivity values were good but not great. Apparently the one string with 6 panels facing SW were not producing as much as they could have - they were being curtailed by the panels to the SE. When the SE panels started decreasing output after noon hour, the SW panels should have been increasing. I monitored the output and it didn't seem as much as it should have been. After 19 April, it appeared to me that the SW panels performed better. I did this comparison by examining output on separate clear blue sky days before and after the changes. I know that no two days are alike, but it seemed to have improved.
However, over the summer, over this summer the productivity was greater than 4.4, even as high as 5.0 kWhrs/kW installed. Very clear skies!

		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	699	3661
	Average - Efficiency [kWhr/kW]		2.6	3.3	3.0	3.2	3.4	3.6	3.2
May	Sum - Daily kWhr		534	758	768	699	745	875	4378
	Average - Efficiency [kWhr/kW]		2.7	3.8	3.9	3.5	3.8	4.4	3.7
Jun	Sum - Daily kWhr		707	715	633	757	687	965	4464
	Average - Efficiency [kWhr/kW]		3.7	3.7	3.3	3.9	3.6	5.0	3.9
Jul	Sum - Daily kWhr		769	762	693	735	821	889	4669
	Average - Efficiency [kWhr/kW]		3.9	3.8	3.5	3.7	4.1	4.5	3.9
Aug	Sum - Daily kWhr	164	658	720	711	694	693	876	4515
	Average - Efficiency [kWhr/kW]	3.2	3.3	3.6	3.7	3.5	3.5	4.4	3.7
Sep	Sum - Daily kWhr	438	528	600		626	625	743	3560
	Average - Efficiency [kWhr/kW]	2.3	2.8	3.1		3.3	3.3	3.9	3.1
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	6050	36363
Total Average - Efficiency [kWhr/kW]		1.8	2.4	2.6	2.4	2.5	2.8	3.5	2.6

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.