Generation Results up to June 2012

A quick post here to share my June power generation. It was a great month, and so far every month this year has been better than last year. Much more sun, not as much snow.

Sum - Revenue, daily	Years
Date	2010	2011	2012	Total Result
Jan		$136.10	$205.18	$341.29
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	$61.57	$678.32
Aug	$131.53	$528.09		$659.62
Sep	$351.28	$423.49		$774.77
Oct	$360.90	$313.65		$674.55
Nov	$285.03	$253.69		$538.72
Dec	$62.74	$176.31		$239.05
Total Result	$1,191.47	$4,509.43	$2,664.65	$8,365.55

December 2010 Power Production

December was generally -8 to -1 with about 10 cm snowfall mid-month. The second half of the month was almost always overcast. A thaw with rain melted all the snow on 27 Dec.
The panels were snow-covered most of the second half of the month and power generation was significantly reduced (see chart, Whr/day). The overcast days which were slightly below 0C did not provide sufficient radiant heat to warm the panels and melt all the snow off. This was clearly shown in the previous postings of the snow-covered panels. Partly sunny days just after Christmas resulted in some snow melt and snow sliding off about half of the panels (see earlier post with photos). This resulted in an increase in generation on 27 Dec.
The remaining days of December were very overcast with heavy dark cloud. Even the melt that occurred on 29 Dec was not sufficient to increase production even though the panels were clear. The increase on 31 December showed the benefit of clear panels and a little sunshine. Fortunately, the clear panels is helping increase generation during the first week of January which are a little more bright. Happy New Year!

Generation Results up to May 2012

The results of the power generated, in kWhr up to May 2012:

Sum - Daily kWhr	Years
Date	2010	2011	2012	Total Result
Jan		170	256	426
Feb		275	323	598
Mar		561	569	1130
Apr		493	626	1119
May		534	758	1292
Jun		707	13	720
Jul		769		769
Aug	164	658		822
Sep	438	528		966
Oct	450	391		841
Nov	355	316		672
Dec	78	220		298
Total Result	1486	5623	2544	9652

And the revenue, gross, generated up to May 2012:

Sum - Revenue, daily	Years
Date	2010	2011	2012	Total Result
Jan		$136.10	$205.18	$341.29
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	$10.30	$577.50
Jul		$616.75		$616.75
Aug	$131.53	$528.09		$659.62
Sep	$351.28	$423.49		$774.77
Oct	$360.90	$313.65		$674.55
Nov	$285.03	$253.69		$538.72
Dec	$62.74	$176.31		$239.05
Total Result	$1,191.47	$4,509.43	$2,040.28	$7,741.18

Data Catch-up!

Several months have gone by without me posting my data - sorry about that. Actually the last posting was 1 September - shame on me. Sorry again!
Our system has now been running for almost 1.5 years and we can now compare data between two months of different years to begin to see how variable the solar energy received is. Since our system was commissioned August 2010, we can now compare September to December (and in a few days January). We know that weather and solar energy will be different between the years, but I didn't know by how much. Also, the effects of weather will affect the solar generation - I'm primarily referring of snow and its persistence. So, on to the data...

Daily Power Generation

The data is downloaded from my Fronius datalogger and creates two M$ excel files: a daily summary file and a instantaneous (15 min average) file. The files report the kWhr, AC and DC voltage, and error messages (never had any error messages. I'll have to do a posting on the AC power but I don't know enough about it to say anything intellegent about it (yet). I add the daily data to a spreadsheet file where I do calculations and the figures.
The annual trend in solar radiation is clearly visible now that we have more than a full year cycle in Figure 1. There is considerable daily variability - as much as 30 kWhr for the system or 6 kWhr per kW per day. The highest variability is during the spring months of March and April. In August and September the variability ranges about 20-25 kWhr or 5 kWhr per kW per day. One reason for the larger daily variability in the spring months is because the overall potential output is highest (35 kWhr) and there is still the good chance that snow covers the panels or there is a very dark overcast day. The days are also still a little short therefore the total accumulated solar radiation will be less than the longer summer days. This is why we see the lowest generation days in mid-summer still seldom being less than 10 kWhr. This means the variability per kW to be closer to 5 kWhr/kW/day and not 6 kWhr/kW/day.
December was an interesting month to compare between the two years. December 2010 received a quite a few snow days and this resulted in many days with very little power generation (see all the points clustered around the x-axis during the second week in Dec with virtually no days over 10-15 kWhr until mid-January. I've (begrudgingly) reported this in an early posting. Even though we love the snow and winter, the good news for December 2011 was that there was virtually no snow fall this year and there were many days where the system generated over 10 kWhr. Several good days over the month makes a big impact on monthly revenue.

Figure 1. Daily Power Generation, 4.9 kW DC PV System

April 2011 Generation Results

The bright sunny days of March have led to rather dreary days of April. This has been very interesting results for our solar power generation. I don't think there was one day in April of totally bright cloud-free days, though I'll check that later. In the mean time I am posting my PV generation to date. Given that the next few days that end April will be very cloudy and wet, I don't expect anything interesting, so I post this a few days before then end of April.
However, a quick note about extremely windy days today and yesterday. There was unconfirmed tornadoes in Kitchener, 20 km to the west of us yesterday, and very strong gusts here in Guelph. Our panels are still on the roof - that's a good thing. I was very impressed that our solar system installer [Merlyn Power]  called this morning to see if we still had panels on our roof or if there was any damage. Very considerate and consciousness of him.
So, the results:

• the middle of March was spectacularly bright as you see in my 03 April post. This continued into early April but mid to end of April were relatively cloudy with lower kWhrs
• 20 April was only 5 kWhrs which was a very rainy and dark day
• cloudy with sunny periods was yielding about 15 kWhrs