Transcript Chapter 7 — Charge Controllers

PowerPoint® Presentation
Photovoltaic Systems
Charge Controllers
Charge Controller Features • Charge
Controller Types • Charge Controller
Setpoints • Charge Controller
Applications
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Chapter 7 — Charge Controllers
Charge controllers
manage interactions and
energy flows between a
PV array, battery bank,
and electrical load.
Chapter 7 — Charge Controllers
Single-stage battery
charging is simpler, but
multistage battery
charging brings batteries
to a higher state of
charge.
Chapter 7 — Charge Controllers
Charge controllers
protect batteries from
overcharge by
terminating or limiting
charging current.
Chapter 7 — Charge Controllers
Charge controllers
protect batteries from
overdischarge by
disconnecting loads at
low battery voltage.
Chapter 7 — Charge Controllers
Most charge controllers
include displays or LEDs
to indicate battery
voltage, state of charge,
and/or present operating
mode.
Chapter 7 — Charge Controllers
Shunt charge controllers regulate charging current by
short-circuiting the array.
Chapter 7 — Charge Controllers
Series charge controllers
regulate charging current
by opening the circuit
from the array.
Chapter 7 — Charge Controllers
Pulse-width modulation
(PWM) simulates a lower
current level by pulsing a
higher current level ON
and OFF for short
intervals.
Chapter 7 — Charge Controllers
Maximum power point
tracking manipulates the
load or output voltage of
an array in order to
maintain operation at or
near the maximum power
point under changing
temperature and
irradiance conditions.
Chapter 7 — Charge Controllers
Diversionary charge controllers regulate charging
current by diverting excess power to an auxiliary load
when batteries are fully charged.
Chapter 7 — Charge Controllers
Controllers designed for
hybrid PV systems must
manage multiple current
sources simultaneously.
Chapter 7 — Charge Controllers
Ampere-hour charge
controllers track the
cumulative number of
ampere-hours applied to
a battery bank and
discontinue charging at a
preset total.
Chapter 7 — Charge Controllers
Charge regulation
setpoints are the voltage
levels at which the
charge controller
interrupts or reconnects
the charging current from
the array to the battery
bank.
Chapter 7 — Charge Controllers
The optimal voltage regulation setpoint depends on the types of
battery and charge controller.
Chapter 7 — Charge Controllers
Load control setpoints
are the voltage levels at
which the charge
controller interrupts or
reconnects the
discharging current from
the battery bank to the
loads.
Chapter 7 — Charge Controllers
The equalization setpoint
brings the battery voltage
to a level that is higher
than the normal charge
regulation voltage.
Chapter 7 — Charge Controllers
Setpoints are adjusted
with controls inside the
charge controller.
Chapter 7 — Charge Controllers
Temperature probes are
placed between batteries
and connect to a charge
controller to compensate
the charge regulation
setpoint.
Chapter 7 — Charge Controllers
Many criteria should be
considered when
selecting charge
controllers for PV
systems.
Chapter 7 — Charge Controllers
Long conductors between
a charge controller and a
battery bank have
resistance that causes
voltage drops. Voltage
drops affect the voltage
measured at the charge
controller, which triggers
overcharge and
overdischarge protections
too early.
Chapter 7 — Charge Controllers
Some charge controllers
use additional battery
voltage sense conductors
to avoid the effect of
voltage drop on
setpoints.
Chapter 7 — Charge Controllers
Larger PV systems often
use independent charge
controllers for each array
source circuit.
Chapter 7 — Charge Controllers
Separate charge
controllers are usually
recommended for
charging independent
battery banks from a
single array.
Chapter 7 — Charge Controllers
In some cases, a single charge controller may be
used to charge independent battery banks.
Chapter 7 — Charge Controllers
To balance the charge to
and from the battery in a
self-regulating PV
system, the load must be
well defined, the battery
must be oversized, and
the array current must be
self-limiting.
Chapter 7 — Charge Controllers
Low-voltage modules
control current into a
battery bank without a
charge controller
because their current
automatically falls as the
battery reaches full
charge.