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Blue Sky Solar Boost 6024HDL, MPPT Charge Controller, 60Amp,12/24 Volt, W/ Display (SB6024HL)
Blue Sky Solar Boost 6024HL,MPPT Charge Controller, 60Amp,12/24 Volt, No Display (SB6024HL)


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Availability: Call for Availability


Blue Sky Solar Boost 60 Amp 12/24 Volt MPPT Charge Controller with Display Option

Options: Display
Manufacturer Part Number: 6024HL

Patented Maximum Power Point Tracking (MPPT) technology allows Solar Boost 6024H to increase charge current up to 30% or more compared to conventional charge controllers. Don’t waste money by throwing PV power away! Get the power you paid for with a Solar Boost charge controller.

Solar Boost 6024H is specially designed to receive a high voltage 36V or 48V PV array input, and charge a 12V or 24V battery at up to 60A. A high efficiency DC-DC voltage converter combined with MPPT technology allows Solar Boost 6024H to provide a cost effective solution for installations where the PV array must be located far from the batteries and charge controller. High voltage input reduces both wiring expense and wiring power loss.

Solar Boost 6024H also provides an advanced fully automatic three stage charge control system to ensure the battery is properly and fully charged, resulting in enhanced battery performance with less battery maintenance. An equalize function is also included to periodically condition liquid electrolyte lead-acid batteries.

An optional user friendly digital display is available to monitor PV charge performance. Optional temperature compensation of charge voltage is also available to further improve charge control and battery performance.


Get Improved Performance From Your PV Modules and Batteries

  • Patented MPPT technology increases charge current up to 30% or more!
  • Special high voltage input design accepts 36V or 48V solar module arrays
  • Charges 12V or 24V batteries at up to 60A output charge current
  • Three stage PWM charge control optimizes charge parameters to battery size & type
  • Electronic current limit prevents overload or nuisance fuse blow
  • Available digital display monitors PV charge performance
  • Durable powder coat finish & conformal coated electronics resist corrosion
  • Fully protected against excess current, temperature, transient voltage & polarity
  • Full 36 month limited warranty, optional extended coverage available
  • ETL listed to UL STD. 1741, certified to CAN/CSA STD. E335-1/2E, CE labeled


Output Current Rating 60 Amp Maximum
Nominal Battery Voltage 12 /24VDC Field Selectable
Nominal PV Voltage 36 VDC / 48VDC (3 or 4 series modules) Field Selectable
PV Open Circuit Voltage 140VDC Maximum
Standby Power Consumption 30mA Typical
Charge On Power Consumption 190 / 120mA @ 12 / 24VDC (with fan operating)
Charge Algorithm 3 stage charge. Acceptance/Float transition based on charge current matched to battery amp-hours. Can accept external shunt signal for optimal charge control with widely varying loads. Selectable for 2 stage charge.
Acceptance Voltage Setpoint 13 - 16VDC / 26 - 32VDC
Float Voltage Setpoint 0 - 2VDC / 0 - 4VDC < Acceptance
Equalization Voltage Acceptance + 1.0 / 2.0VDC
Voltage step-down Cannot operate as conventional 12VDC or 24VDC charge controller. Must operate in high voltage input / low voltage output step-down mode
Temperature Compensation Optional temperature sensor adjusts charge voltage setpoint based on measured battery temperature. Field selectable slope, -5.0mV/ºC/cell (lead-acid), or -2.0mV/ºC/cell (NiCd)
Power Conversion Efficiency 95% @ 28 Volt 50 Amp Output
Digital Display Available in the unit, as a remote, or both. Shows PV input current, output charge current, battery voltage, charge mode, and state of charge. Remote display mounts in standard duplex box, includes 25 Ft. (7.6m) cable. Maximum cable length to 300 Ft. (91.4m)
Cabinet Dimension 10” H x 8-3/4” W x 3” D (25.5cm x 22.6cm x 8.74cm)
Digital Display Range/Accuracy
Voltmeter: 70.0VDC / ±0.30% F.S.
Ammeter: 60.0A / ±0.50% F.S.
Specified Temperature Range 0 to +40ºC (Extended range –40 to +50ºC, will operate but may not meet spec. – see Technical Bulletin 100206)

Detailed Description:

How Do Solar Boost Charge Controllers Increase Charge Current?

Solar Boost controllers increase charge current by operating the PV module in a manner that allows the module to produce all the power it is capable of. A conventional charge controller simply connects the module to the battery when the battery is discharged. When the 75W module in this example is connected directly to a battery charging at 12 volts its power production is artificially limited to about 53 watts. This wastes a whopping 22 watts or nearly 30% of the available power!

Patented MPPT technology used in Solar Boost controllers operates in a very different fashion. The Solar Boost controller continually calculates the module’s maximum power voltage, in this case 17 volts. It then operates the module at its maximum power voltage to extract maximum power. The higher power extracted from the module is then provided to the battery in the form of increased charge current. In conditions where extra PV power is not available, Solar Boost controllers will operate as a conventional controller with very low voltage drop.

The actual charge current increase you will see varies primarily with module temperature and battery voltage. In comfortable temperatures, current increase typically varies between 10 to 25%, with 30% or more easily achieved with a discharged battery and cooler temperatures. What you can be sure of is that Solar Boost charge controllers will deliver the highest charge current possible for a given set of operating conditions.

About the 6024H

Solar Boost 6024H is Maximum Power Point Tracking (MPPT) photovoltaic (PV) battery charge controller capable of charging 12 or 24 volt batteries at up to 60 amps. The Solar Boost 6024H is specially designed to accept a high PV input voltage of nominal 36 volts or 48 volts from a series connection of three (3) or four (4) conventional 36 cell PV modules. This high input voltage capability can greatly reduce PV wiring costs when the PV modules must be located an appreciable distance from the charge controller. Through the use of patented MPPT technology, Solar Boost 6024H can increase charge current up to 30% or more compared to conventional controllers. Solar Boost 6024H’s sophisticated three stage charge control system can be configured to optimize charge parameters to precise battery requirements based on battery electrolyte type, battery size in amphours, and battery temperature. The unit is fully protected against voltage transients, over temperature, over current, and reverse polarity connections. A manual equalize function is provided to periodically condition flooded lead-acid batteries. Solar Boost 6024H also includes an automatic current limit feature which allows use of the full 60 amp capability without worrying about overload or nuisance fuse blow from excessive current.

Solar Boost 6024H employs series pass Pulse Width Modulation (PWM) charge voltage control. The multistage charge control system combined with precise PWM voltage control leads to superior charging and enhanced battery performance. To provide optimum charge control on installations where battery load varies widely during charge, Solar Boost 6024H can interface to an external current shunt to provide optimal charge control. The PWM control system uses highly efficient and reliable power MOSFET transistors. The MOSFET’s are turned on and off at high frequency to precisely control charge voltage and MPPT. Environmentally sealed high current high reliability relays are used to disconnect the PV array at night to prevent unwanted current drain. Relays are used rather than blocking diodes for improved power conversion efficiency, current boost performance, and true reverse battery polarity protection in an MPPT controller. The relays are not stressed by functioning as part of the voltage control system and continually turning on and off as with other PV controllers.

Fully automatic temperature compensation of charge voltage is available as an option to further improve charge control and battery performance. The available SensorLug™ battery temperature sensor is built for long term reliability. The sensor element is environmentally sealed and encapsulated into a copper lug which mounts directly to the battery terminal. A user friendly digital display is also available to monitor PV charge performance. The display may be provided in the Solar Boost 6024H controller, as a remote panel, or both. The remote panel cable may be up to 300ft/91.4m in length.

Variations & Accessories

SB6024HL Solar Boost 6024H controller without digital display
SB6024HDL Solar Boost 6024H controller with digital display
SB50RD25 SB6024H remote digital display with 25’ cable (standard duplex box mount)
SB6024HPDL SB6024HDL front panel with digital display (add to SB6024HL to make SB6024HDL)
930-0022-20 SensorLug battery temperature sensor with 20’ cable
CS-100 100A/100mV current shunt
CS-200 200A/200mV current shunt
CS-500 500A/50mV current shunt

Maxiumum Power Point Tracking (MPPT)

MPPT and associated current boost operation is fully automatic and will function whenever sufficient PV current is available. The unit requires a minimum PV input current of approximately 2.5A for the MPPT system to operate and raise PV voltage to the optimum value where the PV array can produce maximum power. The percent increase in output charge current relative to charge current that would be seen with a conventional charge controller is variable, and will change with operating conditions. Output current will vary as available PV power changes with operating conditions.

The principal operating conditions which affect current boost performance are battery voltage and PV array temperature. At constant solar intensity available PV array power changes with array temperature. A PV array’s power vs. temperature characteristic is such that a cool PV array can produce a higher voltage and more power, than a hot PV array. When PV current is sufficiently high for MPPT to operate, a constant power output is delivered to the battery. Since output power is constant while MPPT is operating, a decrease in battery voltage produces an increase in charge current. This means that the greatest current increase occurs with a combination of cool ambient temperature and low battery voltage. The unit delivers the greatest charge current increase when you need it most, in cold weather with a discharged battery.

Because output power is constant while boost is operating, anything that leads to lower battery voltage will produce an increase in output charge current. While a discharged battery is one way to produce lower output voltage, and therefore higher output current, other normal conditions may produce lower voltage as well. Any DC power consumption during the day will decrease net battery charge current, which decreases battery voltage. Operating a large inverter or application of other heavy loads can produce substantial drops in output voltage leading to significant increases in output current. Additionally, anything that can be done to lower PV array temperature will also lead to increased charge current by increasing PV power production. Installing modules in a breezy location for example will cool the PV array due to increased air circulation.

How MPPT Works

A PV module is a constant current device. A typical PV module voltage vs. current curve shows current remains relatively constant over a wide range of voltage. A typical 75 watt module is specified to deliver 4.45 amps @ 17 volts @ 25°C. Conventional PV controllers essentially connect the PV array directly to the battery when battery voltage is low. When a 300 watt series/parallel array of four 75 watt modules are connected in the normal fashion directly to a battery charging at 24 volts, the modules still provide approximately the same current. But, because output voltage of each of the two series strings is now held artificially low at 24 volts by the battery rather than 34 volts (2x17V), each series string only delivers 107 watts (24V x 4.45A) for a total power delivered to the battery of 214 watts. This system delivers only 8.90 amps (2 x 4.45A) of charge current while wasting 86 watts of available power.

A PV module is a constant current device. A typical PV module voltage vs. current curve shows current remains relatively constant over a wide range of voltage. A typical 75 watt module is specified to deliver 4.45 amps @ 17 volts @ 25°C. Conventional PV controllers essentially connect the PV array directly to the battery when battery voltage is low. When a 300 watt series/parallel array of four 75 watt modules are connected in the normal fashion directly to a battery charging at 24 volts, the modules still provide approximately the same current. But, because output voltage of each of the two series strings is now held artificially low at 24 volts by the battery rather than 34 volts (2x17V), each series string only delivers 107 watts (24V x 4.45A) for a total power delivered to the battery of 214 watts. This system delivers only 8.90 amps (2 x 4.45A) of charge current while wasting 86 watts of available power.

Solar Boost 6024H’s patented MPPT technology operates in a very different fashion. Consider a system where the four 75 watt modules are connected in series for a nominal 48 volt input, charging the same 24 volt battery. Under these conditions Solar Boost 6024H calculates the maximum power voltage (VMP) at which the PV module delivers maximum power, in this case 17 volts. It then operates the PV module string at 4x17 volts or 68 volts which extracts maximum power from the modules. Solar Boost 6024H continually recalculates the maximum power voltage as operating conditions change. Input power from the MPPT controller, in this case full 300 watts, feeds a switching type power converter which reduces the 68 volt input to battery voltage at the output. The full 300 watts which is now being delivered at 24 volts would produce a charge current of 12.5 amps. A charge current increase of 3.6 amps or 40% is achieved by converting the 86 watts that would have been wasted into useable charge current. Note that this example assumes 100% efficiency to illustrate the principal of operation. In actual operation, charge current increase will be somewhat less as some available power is lost in wiring, connections, and in Solar Boost 6024H.

Typical Current Boost Performance

As described above, current boost performance for a particular installation varies primarily with PV array temperature and battery voltage. Two other factors which affect boost performance include system wiring and PV module design. The effect wiring has on performance is power wasted heating undersized wiring is unavailable for charging. This is discussed further in the Battery And PV Wiring section. The effect PV module design has on performance is 36 cell modules with a maximum power voltage (VMP) of 17 volts or higher will tend to produce more boost, whereas modules with VMP less than 17 volts will tend to produce less boost. Module types with a high VMP value in the range of 17.0-18.5V provide the best boost performance since there is more typically untapped power to be extracted. For a 24 volt system using eight 75 watt modules in series with peak power specifications of 4.45 amps @ 17 volts @ 25°C, representative boost performance under a variety of operating conditions is shown in Table 2. Your current boost performance will vary due to a variety of factors. What you can be sure of is that Solar Boost 6024H will deliver greater total charge current when conditions are such that the modules have extra power to extract.

Charge Status Indicator

An LED charge status indicator is provided both with and without the optional digital display. Indicator function is identical for the SB6024HL, SB6024HDL, and SB50RD25.

Charge Status Indicator Charge Mode Approximate Charge Level
Off Charge off -
Continuously On Bulk < 70% full
Blinking: 1 sec on / 1 sec off Acceptance 70% - 95% full
Blinking: 0.2 sec on / 1 sec off Float Fully Charged
Rapid Blinking: 0.2 sec on / 0.2 sec off Equalize -

Optional Digital Display

An optional digital display is available to monitor PV charge performance. The display is available installed controller chassis, and as a remotely mounted panel. Both the chassis display and the remote display may be installed and used simultaneously. The digital display can be selected to show Battery Voltage, Solar Panel Current, or Output Charge Current. When the MPPT system is functioning, charge current boost can be seen by noting the difference between Solar Panel Current and Output Charge Current. If MPPT is not operating, it is normal for Output Charge Current to show 0.1 amps less than Solar Panel Current since the system consumes 100/70mA at 24/48V respectively to operate during charge.

Three Stage Charge Control

Solar Boost 6024H is typically configured for a three stage charging process, Bulk, Acceptance and Float. The most highly optimized charge process is obtained by using the optional battery temperature sensor, and if battery load varies during charge, an optional external current shunt to determine full charge based on net battery charge current.

Bulk Charge

During the bulk charge stage the battery is typically less than 70% charged, and the unit delivers as much charge current as possible to rapidly recharge the battery. Bulk charge occurs when; 1) Charge current during float increases above the Float Transition Current setting, or 2) Insufficient charge current is available to hold the battery at the desired acceptance or float voltage. Electronic current limit prevents the possibility of overload by limiting output current to 60 amps regardless of PV input current or power.

Acceptance Charge

When sufficient charge has been recovered for the battery to reach the acceptance voltage setpoint, the unit changes to a constant voltage mode where the acceptance voltage is applied to the battery. The acceptance voltage is factory set to ˜28.6/57.2V. In acceptance, the battery is typically between 70% to 95% charged. When charge current in acceptance decreases to the Float Transition Current setting, typically set to 1.0 to 2.0 amps per 100 amp-hours of battery capacity, the battery is fully charged and the unit switches to float.

Float Charge

Once the battery is fully charged the unit switches to float, where the float voltage is applied to the battery to maintain it in a fully charged state without excessive water loss. The float voltage is factory set to ˜26.6/53.2V. During float a healthy lead-acid battery will draw approximately 0.1–0.2 amps per 100 amphours of battery capacity.

Two Stage Charge Control

Certain battery types or system configurations (such as grid tied systems) may require two stage charge control. Solar Boost 6024H can be configured for a two stage bulk-acceptance or bulk-float charging process to accommodate these batteries or systems.


Equalization is essentially a controlled over charge and should only be performed on vented liquid electrolyte lead-acid batteries. Since each cell of a battery is not identical, repeated charge/discharge cycles can lead to an imbalance in the specific gravity of individual cells and to electrolyte stratification. Equalization brings all battery cells up to the same specific gravity and eliminates stratification by heavily gassing the battery. Note that the optimal three stage charge technique matched to battery size, type and temperature provided by Solar Boost 6024H minimizes the need for equalization.

Equalization is normally conducted approximately once per month, with the battery held at the equalization voltage for a period of approximately two hours. It is best to equalize a battery that is already fully charged so that the desired equalization voltage is reached quickly. Following the desired equalization period, the equalization cycle is terminated and normal charge operation is resumed by again pressing the equalization push-button. The battery should then be topped off with distilled water per the battery manufacturers recommendations.

Disabling Equalization

For certain battery types or electrical systems, it may be desirable to eliminate the possibility of initiating equalization. This can be accomplished by gently pulling the red equalization push-button cap off of the equalize switch and ensuring that the switch plunger is in the normal down position. Use needle nose pliers and gently rock the cap side to side while pulling.

Temperature and Output Power

Over temperature protection is provided to protect the unit from damage due to high output power at high ambient temperatures. When mounted vertically as described in the installation section, the unit can deliver full output in an ambient temperature of up to 40°C (104°F). If an over temperature condition exists, the unit will cycle on/off, reducing average power delivery to within safe limits. During periods of thermal shutdown the Charge Status Indicator will display an “off” condition.

Optional Temperature Compensation

The charge voltage required by batteries changes with battery temperature. Temperature compensation of charge voltage enhances battery performance and life, and decreases battery maintenance. Automatic temperature compensation can be provided through use of the optional SensorLug battery temperature sensor. Temperature compensation curves for either leadacid or NiCd battery chemistry can be selected. The lead-acid curve for a 24 volt system (12 cells) is –60.0 millivolts/°C or –33.3 millivolts/°F, whereas the 24 volt NiCd curve (20 cells) is –40.0 millivolts/°C or –22.2 millivolts/°F. These values double for a 48 volt system. The graph of Figure 2 shows lead-acid charge voltage setpoint vs. battery temperature for the factory acceptance voltage setting of 28.6/57.2V @ 80°F, and float voltage setting of 26.6/53.2V @ 80°F.

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