TriStar MPPT 600V Installation & Operation Manual

38 Operation
Operation4.0
The TriStar MPPT 600V operation is fully automatic. After installation is completed, there are few
operatortaskstoperform.However,theoperatorshouldbefamiliarwiththeoperationandcare
of the TriStar MPPT 600V as described in this section.
4.1 TrakStar
TM
MPPT Technology
The TriStar MPPT 600V utilizes Morningstar’s TrakStar
TM
Maximum Power Point Tracking
(MPPT) technology to extract maximum power from high voltage solar arrays commonly used in
grid-tie applications. The tracking algorithm is fully automatic and does not require user adjust-
ment. TrakStar
TM
technology tracks an array’s maximum power point as it varies with weather
conditions, ensuring that maximum power is harvested throughout the course of the day.
Power Conversion
The power into the TriStar MPPT 600V is the same as the power out of the TriStar MPPT 600V.
Asystemmayhave5AmpsofsolarcurrentowingintotheTriStarMPPT600V and 50 Amps of
chargecurrentowingouttothebattery.Sincepoweristheproductofvoltageandcurrent(Volts
x Amps), the following is true*:
(1) Power Into theTriStar MPPT 600V = Power Out of the TriStar MPPT 600V
(2) Volts In x Amps In = Volts Out x Amps Out
* assuming 100% efficiency -- wiring and conversion losses neglected.
If the solar module’s maximum power voltage (V
mp
) is greater than the battery voltage, it follows
that the battery current must be proportionally greater than the solar input current so that input
and output power are balanced. The greater the difference between the V
mp
and battery voltage,
the greater the current “boost”. Current boost can be substantial in systems where the solar array
is of a higher nominal voltage than the battery as described in the next section.
High Voltage Strings and Grid-Tie Modules
AnotherbenetofTrakStar
TM
MPPT technology is the ability to charge batteries with solar arrays
of higher nominal voltages. The TriStar MPPT 600V charges a 48 Volt battery bank with a high
voltage solar array. The solar array open circuit voltage (V
oc
) rating must not exceed the 600 Volt
maximum input voltage rating at worst-case (coldest) module temperature. The solar module
documentation should provide V
oc
vs. temperature data.
Highersolarinputvoltageresultsinlowersolarinputcurrentforagiveninputpower.Highvoltage
solar input strings allow for smaller gauge solar wiring. This is especially helpful and economical
for systems with long wiring runs between the controller and the solar array.