A charge controller is an electronic voltage regulator used in systems with battery banks to keep the voltage to the battery within acceptable limits. The charge controller automatically tapers, stops, or diverts power when batteries become fully charged. Charge controller capacities range from 4 to 80 A and multiple charge controllers can be used in parallel for larger systems. Some charge controllers offer additional features, like charge status display, datalogging, automatic battery equalization charging, generator starting and even lighting controls.
The simplest charge controllers cut the power when the battery reaches a set voltage, and turn it on when a low voltage set point is reached. Pulse width modulated (PWM) charge controllers turn on and off very rapidly, maintaining the batteries at full charge with whatever power is available. Maximum power point tracking (MPPT) charge controllers optimize the voltage of the PV array to maximize total power output then convert that to the correct voltage to charge the battery. This process significantly increases the power from a solar array, particularly in low temperatures when battery voltage is significantly below the PV array voltage. Most MPPT charge controllers work with higher array voltages, enabling the use of larger solar modules, which can be more economical on a cost per watt basis. A higher voltage solar array also minimizes the required wire size between the array and the charge controller. While more expensive than PWM controllers, MPPT charge controllers can boost system performance by up to 30%.
MPPT Charge Controllers
The table below shows recommended maximum nameplate PV array sizes. The sizes shown can be exceeded by up to 20% without
damaging the controller, but some "clipping" of potential peak current may occur under cool, clear conditions. While exceeding these wattages may reduce power harvest at peak times of the day, the total daily amp-hours delivered to the battery bank will be greater because the larger array will produce more power in less than peak conditions such as mornings, afternoons, and in hazy or cloudy weather.
FLEXmax_60 MPPT Charge Controllers
The FLEXmax MPPT software algorithm is both continuous and active, increasing PV array power yield up to 30% compared to non-MPPT controllers. FLEXmax charge controllers can operate at their maximum rated current in ambient temperatures as
high as 104°F (40°C) and can be used with battery systems from 12 to 60 VDC with PV open-circuit voltage as high as 150 VDC. The controller's set points are fully adjustable to allow use with virtually any battery type, chemistry and charging profile.
The XW-MPPT80-600 can accommodate open circuit voltages of up to 600 VDC, which reduces wiring needs, increases module selection and string sizing flexibility, and enables greater distance between the power source and battery bank. The MPPT PV array input window is 195 to 550 VDC, which supports an output of up to 80 A for 24 or 48 VDC battery banks.
The XW-MPPT80-600 regulates the battery voltage and output current based on the amount of energy available from the PV array and the present state-of-charge of the battery. Standby power draw is less than 1 W.
The charge controller has a configurable single-function auxiliary output to drive a load control relay or to activate devices such as vent fans or indicator alarms. Full output power of 4,800 W is available without de-rating in ambient temperatures up to 113°F (45ºC). Over-temperature protection de-rates the power throughput when ambient temperatures are higher. The XW-MPPT80-600 also features protections for input over/under voltage, output over current, and back-feed (reverse current). Built-in ground fault protection (GFP) eliminates the need for a separate GFP breaker. This unit is configurable for positive, negative, and ungrounded PV systems.
The XW-MPPT80-600 can be used with the XW power distribution panel, or stand-alone in other PV systems with a SqD HU361RB 600 VDC array disconnect. For two strings, wire both poles of the disconnect into the controller terminals. Use a 100 A breaker on the battery side of the control.
A battery temperature sensor is included with the controller. The XW-MPPT80-600 is compatible with Xanbus-enabled devices, such as the XW Series inverter/charger, the System Control Panel (SCP), XW Automatic Generator Start (XW-AGS), and other XW solar charge controllers through the Xanbus network. It can also be installed in a stand-alone mode with an XW System Control Panel (XW SCP).
XW-MPPT80-600 dimensions are 30"H x 8.63"W x 8.63"D, weight is 29.8 lbs and it is covered by a 5-year warranty with an optional extension to 10-years. Listed to UL 1741 and CSA 107.1 for the U.S. and Canada.
The SunSaver MPPT charge controller is designed for 12 VDC and 24 VDC battery charging from PV modules with a maximum open circuit voltage of 75 VDC. Use up to three 36-cell PV modules in series or a single 60-cell or 72-cell module to provide up to 200 W when charging a 12 VDC battery or up to 400 W when charging a 24 VDC battery.
The SunSaver MPPT provides an estimated 5-25% more power vs. a simple on-off controller. The controller features electronic protection from short circuit, overcurrent, reverse polarity, high temp, high voltage, lightning and transient surges. An adjustable low-battery load disconnect protects the battery from over-discharge. LED indicators indicate charging, low-battery and faults. Mounts on DIN rail with DIN-1 rail clip. SS-15MPPT dimensions are 6.6 x 2.75 x 2.2 inches, weight is 1.65 lbs, and it is covered by a 5-year warranty. Listed to UL 1741 CSA 107.1 for USA and Canada.
This efficient line of PV charge controllers incorporates constant voltage PWM to make maximum use of valuable PV power. They have automatic equalization and temperature compensation. The ProStar controllers can be used on 12, 24 and 48 VDC systems with sealed, gel and wet-cell lead-acid batteries. Front panel LEDs indicate charging status and state-of-charge. Reverse polarity protection on input and output prevents inadvertently damaging the charger. Short circuited loads are automatically disconnected. M models include an LCD meter to display battery voltage, PV charging current, and load current. Low voltage disconnect (LVD) is current-compensated to prevent false disconnect when the battery is heavily loaded. Internal circuitry is conformal coated to guard against corrosion. ProStar dimensions are 6.01" x 4.14" x 2.2" and each unit is covered by a 5-year warranty.
The SunSaver is a reliable charge controller that uses the same battery charging algorithm and offers many of the advantages of the ProStar for smaller systems at a reduced cost. Constant voltage pulse width modulation (PWM) provides a significant performance boost. SunSavers are field-selectable for sealed or flooded batteries. A rugged anodized aluminum case and epoxy encapsulated electronics enhance durability and longevity. A temperature compensation sensor in the charge controller varies full charge voltage with temperature. Low-voltage disconnect (LVD) models have LED charging and load control indicators. SunSaver dimensions are 6" x 2.2" x 1.3" and they are covered by a 5-year warranty. These Gen3 SunSaver Controllers are Listed to Class 1 Div 2 and UL1741 for the USA and Canada.
This controller also includes a backlit remote meter that may be mounted flush with or on a wall, and displays alpha-numeric and graphical information about the solar power system status. The SunSaver Duo is epoxy encapsulated for environmental protection, is user adjustable via DIP switch or connection to a personal computer, and has an optional remote temperature sensor. It is covered by a 5-year warranty.
Xantrex C-35, C-40 and C-60 PWM Controllers
The Xantrex C-35, C-40, and C-60 PWM (pulse width modulator) controllers can be used as either PV charge controllers, DC load controllers or DC diversion regulators in 12 and 24 VDC systems (the C-40 can also be used in 48 VDC systems). Two controllers can be used together to provide multiple functions. As DC load controllers, they disconnect the load at a user-defined low voltage and reconnect at a higher voltage reconnect point. As diversion controllers, they send excess power to a diversion load (see Controls and Relays) to regulate hydroelectric or wind generators. The maximum current throughput is reduced by 25% when used in diversion mode. All Xantrex charge controllers have field-adjustable bulk and float set points and perform automatic equalization every 30 days or whenever low-voltage disconnect (LVD) is reached. Equalization can be manually initiated with automatic shut-off. The optional temperature sensor can be used to increase accuracy of the control algorithms. The optional LCD digital display shows battery voltage, array current and power, cumulative amp-hours and a separately resettable "trip" amp-hour measurement. The digital display can be mounted on the front of the charge controller, or with a cable for remote mounting in a double-gang electrical box up to 100 feet away. These controllers are Listed to UL 1741 and CSA 22.2 No 107.1-95 and covered by a 2-year warranty.
The C-12 controller is PWM microprocessor-based and has a 12 A low-voltage disconnect (LVD) and an automatic lighting control, making it well-suited for small remote loads such as signs, cabins and bus shelters. The lighting control activates the light at dusk, has an adjustable duration timer for 2 to 8 hours of run time, and can be set to run until dawn. The LVD shuts off the load when the battery voltage falls below a user-defined set point. For use in 12 VDC systems only. The C-12 can be mounted outdoors. Its dimensions are 6.5" x 4.3" x 1.5" and it is UL Listed and covered by a 2-year warranty.