To Next Page

To Previous Page

Applications

900-0209-01-00 Rev A

Temperature Conditions

PV voltages are specified at room temperature but change inversely with ambient temperature changes.

Higher temperatures result in lower V

and V

. Lower temperatures result in higher V

and V

Excessively cold weather can cause the V

to rise above the array’s rated limit. A poorly-sized array can

exceed 300 V

and damage the controller. To avoid exceeding the maximum voltage in very cold

temperatures, make certain to calculate the maximum V

using the module temperature correction factor.

If the specific voltage temperature correction factor is not known for a particular module, allow for ambient

temperature correction using the following information:

25° to 10°C (77° to 50°F) multiply V

by 1.06

9° to 0°C (49° to 32°F) multiply V

by 1.10

–1° to –10°C (31° to 14°F) multiply V

by 1.13

–11° to –20°C (13° to –4°F) multiply V

by 1.17

–21° to –40°C (-5° to –40°F) multiply V

by 1.25

Maximum Power Point Tracking

Maximum Power Point Tracking (MPPT) is the technology used by FLEXmax charge controllers to

optimize the harvest of power from PV arrays.

PV modules do not have a defined operating voltage. Their voltage is defined strictly by the load

connected to them. With no load (disconnected), a module displays “open-circuit” voltage (V

), and

delivers no current. At full load (shorted), a module has no voltage, although it delivers the maximum

“short-circuit” current (I

). In neither case does it produce usable wattage.

When partially loaded, a PV module delivers partial current and voltage. These numbers can be

multiplied to see the available wattage. However, the delivery of wattage is not linear. The current and

voltage delivered at a given load will change with the load, along a curve such as that shown in the

drawing to the left in Figure 53. This is known as the I-V curve. The wattage is different at every point

along the curve. (The I-V curve also varies with module type and manufacturer.) Only one point on the

I-V curve represents the delivery of the module’s maximum (rated) wattage. This is known as the

maximum power point, or MPP. The current at this point, I

, is the highest that can be drawn while still

maintaining the highest voltage, V

The FLEXmax 100 controller places a variable load on the PV array and tracks the result to determine the

maximum power point. This process, MPPT, is maintained so that the controller can deliver the maximum

PV power regardless of any change in conditions. The drawing to the right in Figure 53 shows the MPP

and compares the I-V curve against the available wattage.

Figure 53 Maximum Power Point Tracking

OLTAGE

CURRE

I-

curve Available watta

Brand	OutBack Power
Model	FLEXmax 100
Category	Controller
Language	English

OutBack Power FLEXmax 100 User Manual

Table of Contents

Questions and Answers:

OutBack Power FLEXmax 100 Specifications

Related product manuals