PT-100 Manual

Page 19
© 2017 Sensata Technologies
Installation
Examples - Determining the array’s maximum voltage:
Using the correct formula (based on which module’s temperature coeffi cient method is provided)
and the values in our scenarios below, fi rst determine the module’s maximum output voltage
(V
OC-MAX
), and then use this value to fi gure the maximum number of modules that can be connected
in series.
Find the maximum number of PV modules in series to use with the PT-100 (with
αV
OC
coeffi cient provided in percentage):
Scenario: The module has an open circuit voltage rating of 37.4V
OC
at STC (25°C), and the
V
OC
temperature coeffi cient is -0.351%/°C. The modules are going to be installed in an area
where the temperature has dropped to a record low of -18°C. The controller is connected to
a 48-volt nominal battery bank where the highest charging voltage required will be 66 volts.
1. What is the module’s maximum voltage (V
OC-MAX
)? 43.0V (as calculated below)
V
OC-MAX
= V
OC
× ⟨1 + [(T
LOW
− T
STC
) × αV
OC
(%)]⟩
V
OC-MAX
= 37.4V × ⟨1 + [(-18°C - 25°C) × -.351%/°C}]⟩
V
OC-MAX
= 37.4V × ⟨1 + [-43°C × -.351%/°C]⟩
V
OC-MAX
= 37.4V × ⟨1 + [-43°C × -.00351/°C]⟩
V
OC-MAX
= 37.4V × ⟨1 + .1509⟩
V
OC-MAX
= 37.4V × ⟨1.1509⟩ = 43.04
V
OC-MAX
= 43.0V
2. What is the PT-100’s maximum PV input voltage (see Table 2.1)? 240V (48-volt system)
3. What is the maximum number of modules that may be installed in series? 240V ÷ 43V
= 5.58 = 5 modules (rounded down to the next whole number).
Answer: You should connect no more than 5 of these modules in series to ensure the
array’s voltage stays below the PT-100’s maximum PV input voltage level.
Find the maximum number of PV modules in series to use with the PT-100 (with
αV
OC
coeffi cient provided in voltage):
Scenario: The module has an open circuit voltage rating of 37.8V
OC
at STC and the V
OC
temperature coeffi cient is -.113V/°C. The modules are going to be installed in an area where
the temperature has dropped to a record low of -18°C. The controller is connected to a 48-
volt nominal battery bank where the highest charging voltage required will be 66 volts.
1. What is the module’s maximum voltage (V
OC-MAX
)? 42.7V (as calculated below)
V
OC-MAX
= V
OC
+ [(T
LOW
− T
STC
) × αV
OC
(V)]
V
OC-MAX
= 37.8V + [(-18°C - 25°C) × -.113V/°C]
V
OC-MAX
= 37.8V + [-43°C × -.113V/°C]
V
OC-MAX
= 37.8V + [4.859] = 42.66
V
OC-MAX
= 42.7V
2. What is the PT-100’s maximum PV input voltage (see Table 2.1)? 240V (48-volt system)
3. What is the maximum number of modules that may be installed in series? 240V ÷
42.7V = 5.62 = 5 modules (rounded down to the next whole number).
Answer: You should connect no more than 5 of these modules in series to ensure the
array’s voltage stays below the PT-100’s maximum PV input voltage level.