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Charge Controllers
Batteries that are part of an alternative energy solar PV system require a special charge controller to deal with the
unique nature of their charging source (PV panels). The environment produces a wide variation of daily electrical load conditions that could result in many different conditions
ranging from under-charging during periods of low solar radiation, and over-charging during periods of high solar radiation. Individual or combined effects of these two extremes plus the wide
variation of daily load changes are damaging to batteries.
Charge Controllers protect batteries from complete discharge
and over-charging. In addition they regulate the solar charge current and prevent reverse current leakage into the solar array at night. Some charge controllers offer:
- low battery protection
- low battery load disconnect
- temperature compensation for cold weather charging
- built-in current and voltage metering
- lightning protection
- Maximum Power Point Tracking (MPPT)
Maximum Power Point Tracking (MPPT) is a recent innovation
that allows a system to make full use of arrays that produce more than 15 volts DC output. Most controllers will take the incoming voltage and reduce it to 15 volts DC in order to charge the batteries. The voltage above 15 volts is therefore wasted. An MPPT charge controller will convert the extra voltage above 15 volts into current and use this to charge batteries at a faster rate. This is very useful in systems that have steady usage. It is possible to get up to 30% more out of your solar array using this technique. Naturally, this feature comes at an increased cost, which may preclude their use in some systems.
Pulse Width Modulation (PWM) is a charging technique that compensates for the environmental conditions, the age of the
battery, and the condition of the battery. By sending controlled charging pulses that take into consideration the above conditions PWM provides the following benefits:
- ability to recover lost battery capacity (due to build-up of sulfates),
- maintain high average battery capacities,
- equalize cells to accept an even charge,
- reduce battery heating and gassing,
- adjust for battery aging, and
- self-regulate for voltage drops and temperature effects.
The following is a listing of the brands and models that Quallium deals with:
Outback
The Outback MX60 is our premium charge controller. It is a 60 amp MPPT charge controller that can handle up to 125 Volts
DC open circuit and can charge 12, 24, or 48 V batteries. This allows the use of higher voltage arrays meaning that the distance from the array to the controller can be extended due
to lower line loses. Other features include: fully adjustable set-points allowing the use of any battery type, 4 line 80 character backlit display, 64 day power production history
accessible through the display, and five stage charging (bulk, absorption, float, silent, and equalization).
Xantrex
Xantrex provides the C-series charge controller, which is our most popular one. The series contains 4 models that deal
with 12, 35, 40 and 60
amp requirements and has the following features: silent, pulse width modulation microprocessor control; field adjustable voltage and battery set points; standard multi-colour charge status LED (not available on C12 model); and electronic protection against short-circuit, overload, over temperature and reverse polarity conditions.
Morningstar
There are three series of charge controllers available from Morningstar: SunSaver, ProStar, and TriStar. The Morningstar
line is know for having high reliability at reasonable prices. All of the models utilize high standard PWM charging.
The SunSaver series are geared for smaller systems that have 4, 6, 10 or 20 amp requirements. LEDs are used to indicate
charging and low battery.
The ProStar series are geared for mid-range systems that have 15 or 39 amp requirements. It features: Electronic
Protections (Short-circuit and overload for both solar and load); 4 stages of charging; an expected failure rate of less than 1 per 1,000 units over 5 years; and a meter that displays:
- Accurate readings of PV current, load current, and system voltage,
- Temperature,
- LVD and other disconnect conditions, and
- Self-test mode, which displays 9 different controller status parameters and any detected faults (makes it very easy to troubleshoot).
The TriStar series is Morningstar’s newest and most advanced controller geared for larger systems having 45 or 60 amp
requirements. This controller can be used for solar, wind or micro-hydro energy sources. It features:
- a large heat sink allowing operation to 45 deg C without de-rating;
- RS 232 connection for programming via a personal computer;
- 3 status LEDs to indicate status, faults and alarms;
- an optional display that gives extensive system and controller information;
- a tolerance for inrush current up to 300 amps; and
- an operating temperature from –40 to +40 deg C.
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