Go back in time, maybe just 5 or more years, back to the days of solar trackers and tilted arrays. Those were the days! Now all this great technology has given way to the inevitable: Low PV prices.
If you live in Christchurch and want a Grid Tie system then 33 Degrees is the ideal angle for mounting your array.
If aesthetics are important then to keep a low profile we would have designed for a landscape mounting configuration so the array(s) would be longer and lower.
But now you might want to look at this data comparison and perhaps have your array flat mounted to the roof and spend the tilt kit money on a couple of extra panels and larger inverter.... Just a thought but the figures stack up well....
33 degrees:
Station Identification
City:
Christchurch
Country/Province:
NZL
Latitude:
43.48° S
Longitude:
172.55° E
Elevation:
34 m
Weather Data:
IWEC
PV System Specifications
DC Rating:
3.20 kW
DC to AC Derate Factor:
0.850
AC Rating:
2.72 kW
Array Type:
Fixed Tilt
Array Tilt:
33.0°
Array Azimuth:
0.0°
Energy Specifications
Energy Cost:
0.2800 dollars NZL/kWh
Results
Month
Solar Radiation
(kWh/m2/day)
AC
Energy
(kWh)
Energy
Value
(dollars NZL)
1
5.75
453
126.84
2
5.67
407
113.96
3
4.65
371
103.88
4
3.67
288
80.64
5
2.56
204
57.12
6
2.09
162
45.36
7
2.23
180
50.40
8
2.96
242
67.76
9
4.67
366
102.48
10
5.01
407
113.96
11
5.78
451
126.28
12
6.05
482
134.96
Year
4.25
4012
1123.36
10 degrees (same sized array): (less a tilt kit $736 less Labour about half a day $260)
Station Identification
City:
Christchurch
Country/Province:
NZL
Latitude:
43.48° S
Longitude:
172.55° E
Elevation:
34 m
Weather Data:
IWEC
PV System Specifications
DC Rating:
3.20 kW
DC to AC Derate Factor:
0.850
AC Rating:
2.72 kW
Array Type:
Fixed Tilt
Array Tilt:
10.0°
Array Azimuth:
0.0°
Energy Specifications
Energy Cost:
0.2800 dollars NZL/kWh
Results
Month
Solar Radiation
(kWh/m2/day)
AC
Energy
(kWh)
Energy
Value
(dollars NZL)
1
6.02
480
134.40
2
5.57
402
112.56
3
4.26
340
95.20
4
3.11
242
67.76
5
1.99
152
42.56
6
1.55
115
32.20
7
1.70
131
36.68
8
2.42
194
54.32
9
4.09
321
89.88
10
4.81
393
110.04
11
5.93
466
130.48
12
6.42
518
145.04
Year
3.98
3753
1050.84
Same 10 degree angle but with 2 more panels and a larger inverter (an extra $1395 less a tilt kit $736 less Labour about half a day $260)
Station Identification
City:
Christchurch
Country/Province:
NZL
Latitude:
43.48° S
Longitude:
172.55° E
Elevation:
34 m
Weather Data:
IWEC
PV System Specifications
DC Rating:
3.60 kW
DC to AC Derate Factor:
0.850
AC Rating:
3.06 kW
Array Type:
Fixed Tilt
Array Tilt:
10.0°
Array Azimuth:
0.0°
Energy Specifications
Energy Cost:
0.2800 dollars NZL/kWh
Results
Month
Solar Radiation
(kWh/m2/day)
AC
Energy
(kWh)
Energy
Value
(dollars NZL)
1
6.02
540
151.20
2
5.57
452
126.56
3
4.26
382
106.96
4
3.11
272
76.16
5
1.99
171
47.88
6
1.55
129
36.12
7
1.70
147
41.16
8
2.42
219
61.32
9
4.09
361
101.08
10
4.81
442
123.76
11
5.93
524
146.72
12
6.42
583
163.24
Year
3.98
4222
1182.16
The reason tilt kits are not so common is evident here, the price of PV halving in the last 4-5 years has made a big difference to the thinking of how we design systems. The only real downside to the Flat-to-roof mounted array is the winter energy is proportionally less and the summer it's more.
Caution! Do not apply this to Off-Grid system design - the angle of the panels is much more important if you want to make maximum power through the Winter!
