Xandex Solar

SunMizer Module and Inverter Compatibility

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Panel Connectors

SunMizer comes standard with MC3 style connectors. For connection to a panel with MC4 style locking connectors, adapter cables are required for both the input from the panel and the output to the string. Adapter cables are available from leading distributors.

Panel Electrical Specifications

SunMizer supports a maximum DC input open circuit voltage (Voc) from the panel of 48 Voc and a maximum input short circuit current (Isc) of 9A. Local weather statistics and panel manufacturer temperature coefficients must be used when calculating the maximum panel Voc and Isc for a given installation. Given the thermal characteristics of photovoltaic panels, as cell temperature falls below STC* (25°C), panel Voc increases accordingly with the panel’s specific Voc temperature coefficient. If cell temperature rises above STC, panel Isc increases accordingly with the panel’s specific Isc temperature coefficient.

*Important Notes:

  • Standard Test Conditions (STC): Irradiance of 1000W/m², AM 1.5, and cell temperature 25° C.
  • Minimum cell operating temperature is typically experienced at Sunrise and the prescribed record coldest day for the installation location is used for this temperature value.
  • Maximum tested cell operating temperature as specified by the panel manufacturer is used for this temperature value.
  • Calculation to convert from °K to °C: °C = °K – 273.15
  • Calculation to convert from °F to °C: °C = (°F – 32) x (5/9)

Sample temperature-dependent voltage and current correction calculations for SunMizer compatibility determination:

Example A:

Calculate the Maximum Panel Voc (specified using mV/°C temperature coefficient)

Given information:

  • Panel manufacturer specified Voc at STC = 36.4V
  • Panel manufacturer specified Voc temperature coefficient = -122 mV / °C
  • Minimum cell temperature at installation’s geographic location = -20°C

1) Calculate the temperature differential from STC:

(-20°C) – 25°C = -45°C

2) Calculate the change in Voc by multiplying the temperature differential by the temperature coefficient:

(-45 °C) x (-122 mV/°C) x (1V/1000mV) = 5.49V = ΔVoc

3) The maximum panel Voc is calculated by summing the above ΔVoc with the panel manufacturer’s specified Voc at STC:

5.49V + 36.4V = 41.89V = Maximum Panel Voc

Is it compatible with SunMizer?

The calculated Maximum Panel Voc must be smaller than SunMizer’s indicated maximum DC input open circuit voltage (48Voc).

41.89V < 48V (Panel is Voc compatible with SunMizer)>

Example B:

Calculate the Maximum Panel Voc (specified using %V/°C temperature coefficient)

Given information:

  • Panel Manufacturer Specified Voc at STC = 36.5V
  • Panel Manufacturer Specified Voc Temperature Coefficient = -0.34%/ °C
  • Minimum Temperature at Installation Geographic Location = -15°C

1) Calculate the temperature differential from STC:

(-15°C) – 25°C = -40°C

2) Calculate the change in Voc by first multiplying the temperature differential by the temperature coefficient and then multiply the % by the panel manufacturer’s specified Voc at STC::

(-40°C) x (-0.34%/°C) = 13.6% x 36.5V =(0.136) x (36.5V) = 4.96V = ΔVoc

3) The maximum panel Voc is calculated by summing the above ΔVoc with the panel manufacturer’s specified Voc at STC:

4.96V + 36.4V = 41.36V = Maximum Panel Voc

Is it compatible with SunMizer?

The calculated Maximum Panel Voc must be smaller than SunMizer’s indicated maximum DC input open circuit voltage (48Voc).

41.36V < 48V (Panel is Voc compatible with SunMizer)

Example C:

Calculate the Maximum Panel Isc (specified using mA/°C temperature coefficient)

Given information:

  • Panel manufacturer specified Isc at STC = 8.10A
  • Panel manufacturer specified Isc temperature coefficient = 2.43 mA/°C
  • Maximum cell operating temperature at installation = 90°C

1) Calculate the temperature differential from STC:

90°C – 25°C = 65°C

2) Calculate the change in Isc by multiplying the temperature differential by the temperature coefficient:

(65°C) x (2.43 mA/°C) x (1A/1000mA) = 0.158A = ΔIsc

3) The maximum panel Isc is calculated by summing the above ΔIsc with the panel manufacturer’s specified Isc at STC:

0.158A + 8.10A = 8.258A = Maximum Panel Isc

Is it compatible with SunMizer?

The calculated Maximum Panel Isc must be smaller than SunMizer’s indicated maximum input short circuit current (9A).

8.258A < 9A (Panel is Isc compatible with SunMizer)

Example D:

Calculate the Maximum Panel Isc (specified using %A/°C temperature coefficient)

Given information:

  • Panel Manufacturer Specified Isc at STC = 8.00A
  • Panel Manufacturer Specified Isc Temperature Coefficient = +0.04%/ °C
  • Maximum cell operating temperature at installation = 85°C

1) Calculate the temperature differential from STC:

85°C – 25°C = 60°C

2) Calculate the change in Isc by first multiplying the temperature differential by the temperature coefficient and then multiply the % by the panel manufacturer’s specified Isc at STC::

(60°C) x (+0.04%/°C) = 2.40% x 8.0A =(0.024) x (8.00A) = 0.192A = ΔIsc

3) The maximum panel Isc is calculated by summing the above ΔIsc with the panel manufacturer’s specified Isc at STC:

0.192A + 8.00A = 8.192A = Maximum Panel Isc

Is it compatible with SunMizer?

The calculated Maximum Panel Isc must be smaller than SunMizer’s indicated maximum input short circuit current (9A).

8.192A < 9A (Panel is Isc compatible with SunMizer)

System Inverter

The SunMizer algorithm and electrical characteristics are designed and tested to be transparent to the operation of PV system inverters. While central inverters change their load impedance gradually to prevent running the array at sub-optimal conditions during short excursion events such as plane shading or clouds, the SunMizer MPPT algorithm operates to maintain MPP throughout these events, isolating the central inverter from all events except the most extreme conditions.

 



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