|
|
|
Before using these tables, the system designer to insure accurate
current ratings must first perform some calculations and safety
factors are used. For solar modules, good practice requires the
short circuit current (lsc) rating of the PV module is multiplied by
1.25 before other factors are applied. This is because the PV module
electrical performance can increase above the factory rating due to
the combination of increased operating temperatures and enhanced.
These same considerations should be used when selecting a solar
regulator. Be sure to check the Ampacity Chart at higher Amperages.
Scroll down for 24 volt systems
2%
Voltage Drop Chart For 12 Volt Systems
|
Maximum distance in
feet of various gauge two conductor copper wire from power
source to load for 2% voltage drop in a 12 volt system. Do
not exceed the 2% drop for wire between PV modules and
batteries. A 4% to 5% loss is acceptable between batteries
and lighting circuits in most cases, however the cost of the
next larger wire size is usually insignificant and increases
efficiency.
|
|
Amps
|
Watts
|
#14
|
#12
|
#10
|
#8
|
#6
|
#4
|
#2
|
#1/0
|
#2/0
|
#4/0
|
|
1
|
12
|
45
|
70
|
115
|
180
|
290
|
456
|
720
|
.
|
.
|
.
|
|
2
|
24
|
22.5
|
35
|
57.5
|
90
|
145
|
228
|
360
|
580
|
720
|
1060
|
|
4
|
48
|
10
|
17.5
|
27.5
|
45
|
72.5
|
114
|
180
|
290
|
360
|
580
|
|
6
|
72
|
7.5
|
12
|
17.5
|
30
|
47.5
|
75
|
120
|
193
|
243
|
380
|
|
8
|
96
|
5.5
|
8.5
|
11.5
|
22.5
|
35.5
|
57
|
90
|
145
|
180
|
290
|
|
10
|
120
|
4.5
|
7
|
11.5
|
18
|
28.5
|
45.5
|
72.5
|
115
|
145
|
230
|
|
15
|
180
|
3
|
4.5
|
7
|
12
|
19
|
30
|
48
|
76.5
|
96
|
150
|
|
20
|
240
|
2
|
3.5
|
5.5
|
9
|
14.5
|
22.5
|
36
|
57.5
|
72.5
|
116
|
|
25
|
300
|
1.8
|
2.8
|
4.5
|
7
|
11.5
|
18
|
29
|
46
|
58
|
92
|
|
30
|
360
|
1.5
|
2.4
|
3.5
|
6
|
9.5
|
15
|
24
|
38.5
|
48.5
|
77
|
|
40
|
480
|
|
|
2.8
|
4.5
|
7
|
11.5
|
18
|
29
|
36
|
56
|
|
50
|
600
|
|
|
2.3
|
3.6
|
5.5
|
9
|
14.5
|
23
|
29
|
46
|
|
100
|
1200
|
|
|
|
|
2.9
|
4.6
|
7.2
|
11.5
|
14.5
|
23
|
|
150
|
1800
|
|
|
|
|
|
|
4.8
|
7.7
|
9.7
|
15
|
|
200
|
2400
|
|
|
|
|
|
|
3.6
|
5.8
|
7.3
|
11
|
Be sure to check the
Ampacity chart at higher Amperages
5% Voltage Drop Table For 24 Volt Systems
|
The following tables represent the maximum one-way
distance for various wire gauge, voltage and current
combinations based upon a 5% voltage loss for
24volts. Five percent is acceptable in most low voltage
systems, except 12 volt (see above). NOTE: To obtain a 2%
figure from these tables, divide the given distance shown in
the table by 2.5. For calculating distances for 48 volt
systems, multiply the 24 volt distances by 2.
|
|
Amps
|
Watts
|
#14
|
#12
|
#10
|
#8
|
#6
|
#4
|
#2
|
#1/0
|
#2/0
|
#3/0
|
|
1
|
24
|
224
|
356
|
566
|
900
|
1000+
|
1000+
|
. 1000+
|
. 1000+
|
1000+
|
1000+
|
|
2
|
48
|
112
|
178
|
283
|
450
|
716
|
1000+
|
1000+
|
1000+
|
1000+
|
1000+
|
|
4
|
96
|
56
|
89
|
142
|
225
|
358
|
569
|
905
|
1000+
|
1000+
|
1000+
|
|
6
|
144
|
37
|
59
|
94
|
150
|
238
|
379
|
603
|
960
|
1000+
|
1000+
|
|
8
|
192
|
28
|
45
|
71
|
113
|
178
|
285
|
452
|
720
|
908
|
1000+
|
|
10
|
240
|
22
|
36
|
57
|
90
|
143
|
228
|
362
|
576
|
726
|
915
|
|
15
|
360
|
15
|
24
|
38
|
60
|
95
|
152
|
241
|
384
|
484
|
610
|
|
20
|
480
|
|
18
|
28
|
45
|
73
|
113
|
181
|
288
|
363
|
458
|
|
25
|
600
|
|
|
23
|
36
|
57
|
91
|
145
|
230
|
290
|
366
|
|
30
|
720
|
|
|
19
|
30
|
47
|
75
|
120
|
192
|
242
|
305
|
|
40
|
960
|
|
|
|
23
|
35
|
57
|
90
|
145
|
182
|
289
|
|
50
|
1200
|
|
|
|
|
27
|
45
|
73
|
115
|
145
|
183
|
|
100
|
2400
|
|
|
|
|
14.3
|
22.8
|
36.2
|
57.6
|
72.6
|
91.5
|
|
150
|
3600
|
|
|
|
|
|
|
24.1
|
38.4
|
48.4
|
61.0
|
|
200
|
4800
|
|
|
|
|
|
|
18.1
|
28.8
|
36.3
|
45.8
|
Be sure to check the Ampacity chart at higher
Amperages
To achieve maximum efficiency from your power system you do not
want to under-size your wire between various components. If in doubt
use a larger wire size than the charts suggest. The difference in
cost of the next larger-size wire is usually insignificant to the
overall costs, where performance may be affected over the life of
the system. In addition, improperly sized wire can shorten the life
of your components.
Example
A 24V solar array of four Uni-Solar US-64 modules, 2 in series by
2 parallel modules located 30 ft. from the battery; lsc=4.80 A
(two modules); 4.80 x 2 = 9.60A (four modules); 4.80A x 1.25 = 6.0A.
Using the 24 volt table, locate a value equal to or greater than 6
amps from the left column, follow a line to the right until a
distance at or above 30 ft. is found. For this example, using the 24
volt table, we find 6 amps at 37 feet to be the best selection (for
not more than 5% loss) indicating a wire size of #14 AWG. For the
controller, a minimum 10A would be needed - 6.0A x 125% = 7.5A, and
the nearest available size controller is a 10A unit.
Ampacity Chart
|
Maximum ampacity for copper
and aluminum wire
|
|
Wire Size
|
Copper
|
Aluminum
|
|
14
|
25
|
|
|
12
|
30
|
25
|
|
10
|
40
|
35
|
|
8
|
55
|
45
|
|
6
|
75
|
60
|
|
4
|
95
|
75
|
|
2
|
130
|
100
|
|
1
|
150
|
115
|
|
1/0
|
170
|
135
|
|
2/0
|
265
|
150
|
|
4/0
|
360
|
205
|
|
|
