43
TriStar MPPT 600V Operator’s Manual
42
Operation
Operation
4.0
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 power sources commonly used
in grid-tie applications. The tracking algorithm is fully automatic and does not require user
adjustment. TrakStar
TM
technology tracks an power source’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.
s ste
a
a e
s o so ar c rrent o in into t e ri tar
and 50 Amps of
c ar e c rrent o in o t to t e atter
ince o er is t e ro ct o o ta e an c rrent o ts
x Amps), the following is true*:
(1) Power Into the
TriStar 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 power
source is of a higher nominal voltage than the battery as described in the next section.
High Voltage Strings and Grid-Tie Modules
not er enefit o ra tar
TM
MPPT technology is the ability to charge batteries with power
sources of higher nominal voltages. The TriStar MPPT 600V
charges
a 48 Volt battery bank with
a high voltage power source. The power source
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 power source.
4.2 Battery Charging Information
4-Stage Charging
e ri tar
as a sta e atter c ar in a orit
or ra i e ficient an sa e
battery charging. Figure 4-1 shows the sequence of the stages.
NOTE:
Array voltage must be greater than 100 Volts for charging to start
NIGHT
NIGHT
BULK
CHARGE
ABSORPTION
FLOAT
EQUALIZE
VOL
TAGE
TIME
Figure 4-1 TriStar MPPT 600V Charging Algorithm
Bulk Charge Stage
During Bulk charging, the battery is not at 100% state of charge and battery voltage has not yet
charged to the Absorption voltage set-point. The controller will deliver 100% of available solar
power to recharge the battery.
Absorption Stage
When the battery has recharged to the Absorption voltage set-point, constant-voltage regulation
is used to maintain battery voltage at the Absorption set-point. This prevents heating and exces-
sive battery gassing. The battery is allowed to come to full state of charge at the Absorption volt-
age set-point. The green SOC LED will blink once per second during Absorption charging.
The battery must remain in the Absorption charging stage for a cumulative 120 - 150 minutes,
depending on battery type, before transition to the Float stage will occur. However, Absorption
time will be extended by 30 minutes if the battery discharges below 50 Volts the previous night.
The Absorption set-point is temperature compensated if the RTS is connected.