Technical data

PVI 1800/PVI 2500(Rev A) Installation and Operation Manual

DOCR-070570-A

7 Technical Data

Technical Information and specifications – see PVI 1800/PVI 2500

brochure for various other information and data in addition to the

information in this section of the manual. (see Appendix B for info).

Input (DC) from PV array:

 Maximum open circuit voltage of PV array: 400V DC

WARNING: NEC 690-7 must be followed to calculate the maximum number of PV

modules allowed for a maximum inverter open circuit voltage (OCV) of 400V DC in

extreme cold temperatures for the installation location.

 See PV string sizing chart example in Appendix C.

The open circuit voltage of PV modules depends on the cell temperature and the solar

irradiation. The highest open circuit voltage occurs when the PV modules are at the coldest

temperature and in bright sun. (See the following figure – Fig. 10)

0102030

Voltage (VDC)

DC Current (A)

at 50 deg C

at 20 deg C

at -20 deg C

Fig. 10 Example representative ~100W PV module voltage –

current characteristic at various cell temperatures

Because PV modules also have a reduction in voltage at high cell temperatures, you must make sure the

MPP voltage of the strings will not drop below the minimum inverter DC input voltage of 125V DC in

very hot temperature conditions, including wire losses/voltage drop.

Both the maximum open circuit voltage (OCV) when at cold extreme and minimum MPP voltage when at

hot extreme can be calculated for a PV module using its specification sheet. PV module string sizing can

then be used to determine how many modules can/should be used in a string.