Monday, November 2, 2015

Now Solar's #1 Customers Report

 
    Jim Shirts Residents


Jim Shirts was our first customer in the city of Richland Washington. Jim had a quick understanding of solar and did some very extensive research. It was refreshing working with him as he had a great grasp not only on the economics but also the science and applications of solar. Jim agreed to keep a record of his system as I have found over my years in the industry that even with the great satellite information we can utilize, equipment operates differently in different environments. For example we can have some very cold but sunny days that cause panels voltage to raise.

 

Jim's Report
Hi Eugene,
 
On my last utility bill, I received a credit of $86.88 (including tax) for power fed back to the grid…yeah!!!  I’m attaching an update of production info.  I tried to calculate theoretical production based info in “Solar Electricity Handbook”, using orientation, tilt and temperature.  The numbers are close to what you estimated, but I couldn’t get exact insolation data for my orientation and tilt.  Also, I didn’t finish the shading experiment, based on the first test.  Any suggestions on what to do about that?  Hope all is well with you.  Take care.
 
Jim   
 
System Design/Installation/Production Details
Front Panels:
Twelve 270 Watt iTEK panels w/Enphase micro-inverters, roof mounted, facing 50 degrees East of true South, and tilted 72 degrees from vertical (18 degrees from flat).
Back Panels:
Twenty-one 270 Watt iTEK panels w/Enphase micro-inverters, roof mounted, facing 130 degrees WNW from true south, and tilted 72 degrees from vertical (18 degrees from flat).  Three of the panels are affected significantly by shading from a chimney, one is affected slightly by the chimney and two panels are affected slightly by shading early in the year by a large shrub.
(For comparison, the optimum fixed, roof-mounted position would be facing true south and tilted 43.7 degrees from vertical.)
The system was installed in March, 2015 and started producing power in the afternoon of April 2, 2015, with the installation of the city meters.
The actual PV panel average power production, thus far is as follows:
Month
April
May
June
12 Front Panels
42.1 kWh
50.0 kWh
51.6 kWh
15 Back Panels
31.8 kWh
41.7 kWh
44.0 kWh
3 Back Panels w/Major Chimney Affect
23.7 kWh
31.7 kWh
32.1 kWh
1 Back Panel w/Minor Chimney Affect
30.9 kWh
39.5 kWh
40.0 kWh
2 Back Panels w/Minor  Shrub Affect
27.4 kWh
41.4 kWh
44.6 kWh
 
For comparison, the theoretical calculated PV panel power production is:
Month
April
May
June
Front Panels
45 kWh
49 kWh
50 kWh
Back Panels
38 kWh
41 kWh
42 kWh
 
The actual total PV system power production compared to projected, thus far, is as follows:
Month
April
May
June
System Actual Power Production
1140 kWh
1440 kWh
1503 kWh
System Estimated Power Prod.*
1254 kWh
1357 kWh
1395 kWh
 
* Production estimate from Now! Solar.
As can be seem from the above, the actual system production compares favorably with the estimated production from the proposal.

 
Shading Test:
A test was devised to try to quantify the effects of shading on PV panel power production.  The plan was to cover one 6 in. x 6 in. cell in one corner of one panel with a square of white cardboard for one day then compare the production of that panel to an adjacent panel.  Next, two cells would be covered, the test repeated, and then 3 cells covered.   The plan was to start the test before the panels started producing power and then monitor it for the day.
By ~ 8:45 a.m. of the first day of the test, with one cell covered (less than 2% of the panel shaded), the test panel was producing only ~ 50% of the panel next to it (114W vs. 227W).  This was much more significant than expected and due to this result the test was discontinued.  This clearly shows that any amount of shading has a significant effect on power production.    


 
Hi Eugene & Lisa,
 
Was good seeing you at the BF Fair last week, Lisa.  I told you I would provide an update on my system, so here it is:
 
My July credit from the city was $61.01, bringing the total to $286.16, thus far, not counting saved power.  From going hot until the end of June, the state credit due is $1448.64 (4024 kWh generated).  The paperwork was filed but I have not received the check from the city yet.
 
August power production was off as expected, due to the smoke from the wildfires.  Attached is my summary to date:
 
Jim
 
System Design/Installation/Production Details
Front Panels:
Twelve 270 Watt iTEK panels w/Enphase micro-inverters, roof mounted, facing 50 degrees East of true South, and tilted 72 degrees from vertical (18 degrees from flat).
Back Panels:
Twenty-one 270 Watt iTEK panels w/Enphase micro-inverters, roof mounted, facing 130 degrees WNW from true south, and tilted 72 degrees from vertical (18 degrees from flat).  Three of the panels are affected significantly by shading from a chimney, one is affected slightly by the chimney and two panels are affected slightly by shading early in the year by a large juniper shrub.
(For comparison, the optimum fixed, roof-mounted position would be facing true south and tilted 43.7 degrees from vertical.)
The system was installed in March, 2015 and started producing power in the afternoon of April 2, 2015, with the installation of the city meters.
The actual PV panel average power production in kWh, thus far is as follows:
Month
Apr
May
Jun
Jul
Aug*
Sep
Oct
Nov
Dec
12 Front Panels
42.1
50.0
51.6
52.5
41.7
37.0
 
 
 
15 Back Panels
31.8
41.7
44.0
44.0
33.2
24.4
 
 
 
3 Back Panels w/Major Chimney Shade
23.7
31.7
32.1
31.8
25.1
18.5
 
 
 
1 Back Panel w/Minor Chimney Shade
30.9
39.5
40.0
40.9
32.5
16.7
 
 
 
2 Back Panels w/Minor  Shrub Shade
27.4
41.4
44.6
43.7
28.5
24.9
 
 
 
 
For comparison, the theoretical calculated PV panel power production in kWh is:
Month
April
May
June
July
Aug*
Sept
Oct
Nov
Dec
Front Panels
45
49
50
52
50
42
32
19
15
Back Panels
38
41
42
44
42
35
27
16
12
 
The actual total PV system power production in kWh compared to projected, thus far, is as follows:
Month
Apr
May
Jun
Jul
Aug*
Sep
Oct
Nov
Dec
System Actual Power Production
1140
1440
1503
1514
1163
924
 
 
 
System Estimated Power Prod.**
1254
1357
1395
1487
1405
1257
942
499
362
* August energy production was low due to extensive wildfire smoke in area for part of the month.
** Production estimate from Now! Solar.
 
The actual system production compares favorably with the estimated production in the proposal from Now! Solar.
 


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