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1.
Due to the charge controller's starting voltage of 160V
panel modules needed to meet this target voltage at the module's maximum power voltage (V
In this example, consider the Canadian Solar KuPower CS3K-300 solar PV module with a V
of 32.5V at Standard Test Conditions (STC).
•
Five modules in series are required to meet the charge controller's minimum MPPT
tracking voltage requirement: 160V ÷ 32.5V = 4.9 (round up to the next whole
number).
2.
The charge controller's maximum DC voltage input is 550V
module's voltage output: voltage increases as temperature decreases. To calculate the maximum
number of solar panel modules in series per PV string, consider the module's open circuit voltage
(V
) rating, temperature coefficient and lowest expected temperature at the installation site.
OC
In this example, the KuPower 300W module has a V
of 25°C, and a V
OC
����
= ����
To calculate the solar module's V
��������−������������
��������
����
��������−������������
Remember to convert the percentage value given as the V
����
��������−������������
����
•
Twelve modules are the maximum allowable number of modules in series to prevent the solar
PV string from exceeding the charge controller's maximum voltage input rating even in the
coldest weather conditions at the installation site: 550V ÷ 43.3V = 12.7 (round down to the
next whole number).
o
Twelve modules in series at the KuPower 300W module's V
also equates to 390V, well within the charge controller's 120-550V
power point tracking range.
3.
The charge controller's maximum short circuit current (I
slightly affects the solar PV module's current output: current increases as temperature increases.
However, because the temperature coefficient is negligible, it is acceptable to simply use the
module's I
rating at STC for the following calculation.
SC
To calculate the maximum number of solar PV strings per charge controller in this example,
consider the KuPower 300W module's I
•
According to this calculation, two solar PV strings is the maximum allowable number of strings
per charge controller: 21A ÷ 9.82A = 2.13 (round down to the next whole number).
© SIMPLIPHI POWER
temperature coefficient of -0.29%/°C.
× { 1 + [( ����������������
− ����������������
in an extreme low temperature condition of, say, -10°C:
OC
������������
× { 1 + [( −10℃ − 25℃ ) × ( −0.29% ℃
= 39.3����
��������
= 39.3���� × { 1 + [( −10℃ − 25℃ ) × ( −0.0029 ℃
= 39.3���� × �1 + � ( −35℃ ) × �
��������−������������
����
= 39.3���� × { 1 + [( 0.1015 )]}
��������−������������
����
= 39.3���� × 1.1015
��������−������������
����
= ��������. ��������
��������−������������
at STC: 9.82A.
SC
| 19 |
, calculate the minimum number of solar
DC
. Temperature affects the solar PV
DC
of 39.3V at STC, a STC temperature
OC
) × ( ����
���������������������������������������� ���� ���� ���� �������� )]}
������������
��������
⁄ )]}
temperature coefficient to a decimal.
⁄ )]}
OC
−0.0029
���
℃
MP
) input is 21A
. Temperature also
SC
DC
).
MP
MP
rating of 32.5V at STC
maximum
DC
REV2022007071630
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