Solar charge controllers are indispensable components in off-grid solar applications. They connect to both the solar panel and the battery and regulate the battery charge to avoid overcharging and over-discharging. They also prevent the current flowing from the battery back to the panel at night and can monitor the battery temperature to prevent overheating. Voltage regulation when charging a battery is important for the battery's lifespan and healthy operation. There are some charge controllers in the market that support additional features like lighting or DC loads. In these cases, the controller also performs low voltage disconnect (LVC) which is cutting off the load if the battery is low then turn them back on when power is available. Charge controllers can either be stand-alone devices or integrated into the circuitry of a battery-powered device or battery charger. Stand-alone charge controllers are of 2 major types: PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking). PWM and MPPT controllers both adjust the charging rates based on the battery's level but they do so differently.
PWM Charge Controllers
PWM charge controller is the simpler and more affordable of 2 controllers types. This charge controller matches the voltage obtained from the solar panel with the voltage of the battery. The surplus voltage output from the solar panel is discarded. Over the charging period when the battery's voltage rises charge controller draws more voltage from the panel. It's important to note that the solar panel's actual voltage needs to be higher than the battery's nominal voltage otherwise the battery will not charge. By way of example, an 18 Vmp (maximum power voltage) panel is suitable for charging a 12 V battery. The main drawback of PWM charge controllers is that they are inefficient. They have 70% - 80% efficiency which stems from the fact that they drop the panel's output voltage but maintain the same current thus underutilize the available power (loss in wattage).
When choosing a PWM charge controller there are several important considerations to make. Firstly, check the nominal voltage. It shows the voltage of the batteries the controller can work with: for example, 12 V, 24V, etc. Next, look at the amperage rating ("Rated Charge Current") to know the maximum input current the controller can handle. For example, if Rated Charge Current is 20 A and you have three 100W panels with Imp (Maximum Power Current) = 5.59 A then 3 x 5.59 = 16.77 A. To account for the fact that sometimes solar panels can produce more current than the value it is rated for we multiply our last number with 1.25: 16.77 x 1.25 = 20.96 which surpasses the Rated Charge Current of 20 A so the controller is not a good fit for us. Next, look at "Voltage of Solar Panel". Say, it is 50 VDC max. It means it is safe to connect two 100 W solar panels with Voc(Open Circuit Voltage) = 20 V because 2 x 20 = 40 V < 50 V. Other parameters to look at include the suitable cable and battery types (Gel, AGM, Flooded, etc)
- Rated Current: 30 A
- Type: PWM
- Grounding: Negative
This negative-ground controller is designed for off-grid applications. Can be used with a 12 V battery or battery bank. Read more...
Price: US $29.99Related Solar Kits
- Rated Current: 20 A
- Type: PWM
- Grounding: N/A
Designed for home solar power systems and small solar power stations, one USB port for phone charging, automatic detection of 12 V / 24 V systems, IP 22 waterproof rating Read more...
Price: US $30.00Related Solar Kits
- Rated Current: 30 A
- Type: PWM
- Grounding: Negative
Aesthetically appealing negative ground flush mount charge controller designed for an integrated look on an RV wall. LCD display shows operating information and data. Read more...
Price: US $79.99Related Solar Kits
- Rated Current: 30 A
- Type: PWM
- Grounding: N/A
This 30 A PWM solar charge controller by Go Power has a nice design and an ability to be flush-mounted on a wall. Featured Maximum Power Boost Technology (MPBT). Read more...
Price: US $N/ARelated Solar Kits
- Rated Current: 30 A
- Type: PWM
- Grounding: Negative
back-lit LCD display, one 5V / 1A USB port, Temperature compensation, self-diagnostics and electronics protection communication port Read more...
Price: US $39.99
- Rated Current: 20 A
- Type: PWM
- Grounding: Negative
Renogy Voyager is a 20 A waterproof PWM charge controller with back-lit LCD display and LED status lights for charge state identification. Designed for 12 V applications Voyager can charge up to 7 different types of batteries, including Li-ion. Read more...
Price: US $59.99Related Solar Kits
- Rated Current: 10 A
- Type: PWM
- Grounding: Positive
The charge controller has an LCD display which allows a customization of all the parameters. The charge controller is Positive Grounding. Read more...
Price: US $15.99Related Solar Kits
- Rated Current: 10 A
- Type: PWM
- Grounding: N/A
GP-PWM-10-USB charge controller works with AGM, Gel, and Lead Acid batteries. Features a built-in USB port for handheld electronics charging. Read more...
Price: US $75.38Related Solar Kits
- Rated Current: 20 A
- Type: PWM
- Grounding: Positive
The charge controller has an LCD display which allows a customization of all the parameters. The charge controller is Positive Grounding. Read more...
Price: US $19.99Related Solar Kits
- Rated Current: 20 A
- Type: PWM
- Grounding: N/A
Works with 12 and 24 volt battery systems by automatically detecting the battery system voltage. P20L is equipped with a customizable LCD display with symbols to provide status indications of charge, battery status, and system failures. Read more...
Price: US $33.99Related Solar Kits
- Rated Current: 10 A
- Type: PWM
- Grounding: Positive
USB port 5 V / 1.2 A for mobile phone charging and small DC fans, Uses MOSFET as an electronic switch, LED indicators showing battery voltage status. Read more...
Price: US $25.00
- Rated Current: 5 A
- Type: PWM
- Grounding: N/A
This is an IP22 rated waterproof 5 A charge controller by Eco-Worthy. 3-stage charging algorithm impulsive, bulk, floating Read more...
Price: US $12.99Related Solar Kits
- Rated Current: 15 A
- Type: PWM
- Grounding: N/A
This is an IP22 rated waterproof 15 A charge controller by Eco-Worthy. Tiny self-consumption (2 mA @ 12V / <4mA @ 24V). A built-in light sensor suitable for solar outdoor lights, solar pumps, etc Read more...
Price: US $18.99Related Solar Kits
- Rated Current: 35 A
- Type: PWM
- Grounding: Negative
Xantrex C35 heavy-duty charge controller can be used as a charge, diversion or load controller. It comes with a standard multi-color charge status LED faceplate. Read more...
Price: US $101.99Related Solar Kits
- Rated Current: 20 A
- Type: PWM
- Grounding: N/A
Electronic protection against, overload, short-circuit, reverse connection, overcharging, over-discharging, reverse polarity Read more...
Price: US $25.99Related Solar Kits
- Rated Current: 60 A
- Type: PWM
- Grounding: Positive
The multiple load modes of Epever charge controller allows it to be used on a solar home system, solar street light, traffic signal, solar garden light and so on. Read more...
Price: US $64.99
- Rated Current: 60 A
- Type: PWM
- Grounding: N/A
Y-Solar 60 A (80 A version is also available) charge controller is able to take in 720 W @ 12 V and 1440 W @ 24 V. It has a dusk-to-dawn lighting function using daylight sensor. Read more...
Price: US $59.99
- Rated Current: 60 A
- Type: PWM
- Grounding: N/A
Features Positive Ground controller LCD display 2 USB ports Charging/discharging indicator light Battery temperature compensation feature Specifications USB Output 5 V / 1 A Battery Type Lead-acid cell Charging Modes Bulk, Boost, Float, Equalization Load Modes 6 modes Terminals N/A Protections Against over-current low-voltage load short-circuit BlueFire PWM charge controller supports connecting loads to it. Its maximum output power is 720 W @ 12 V and 1440 W @ 24V. . It has an LCD display for parameter readings, LED indicator for charging status, 2 USB ports for mobile device charging. The battery temperature compensation feature automatically adjusts the charging parameters based on the ambient temperature to prolong the battery's life. This charge controller is compatible only with lead-acid cell batteries. The 6 load modes are as follows: Pure light-operated mode, Light and timing mode, 3 light control stages, Manual mode, Normal open mode (24 H), Charge mode. BlueFire charge controller is suitable for usage in environment monitoring, solar power, and lighting systems. The package includes the charge controller and a user manual. Read more...
Price: US $N/AMPPT Charge Controllers
MPPT charge controllers have more advanced circuitry, are more efficient and, consequently, more expensive. What makes MPPT controllers 94% - 99% effective is their ability to track the maximum voltage and current produced by the solar panel in any given moment. By the way, solar inverters also use MPPT algorithm for the maximum power extraction from the solar panel. Like PWM controllers MPPT charge controllers also drop the panel's output voltage to match that of the battery. In the meantime, the controller increases the current so that almost the full power of the panel is utilized. With an MPPT controller, you can charge a 4 x 12 V battery bank using three 20 V (total 60 V) solar panels connected in series. Say, you have three 250 W panels with Vmp = 30.5 A and Imp = 8.19 A. You need at least 13 V to charge each battery so 52 V in total. If you were to use a PWM controller in this setting it would just use 52 x 8.19 = 426 W power that is a 43% energy waste. MPPT controller, on the other hand, will increase the current to 14.42 A to leverage the full power.
- Rated Current: 40 A
- Type: MPPT
- Grounding: N/A
Self-diagnosing capabilities, integrates with Renogy BT-1 Bluetooth module via RS232 port and communicates with Renogy BT mobile app, die-cast aluminum exterior for heat dissipation. Read more...
Price: US $209.99Related Solar Kits
- Rated Current: 20 A
- Type: MPPT
- Grounding: N/A
Die-cast aluminum shell allows for efficient heat dissipation, 99% tracking efficiency, Self-diagnose system faults Error codes can easily be looked up, Auto-detection of 12 V / 24 V systems. Read more...
Price: US $129.99Related Solar Kits
- Rated Current: 40 A
- Type: MPPT
- Grounding: Negative
The charge controller is compatible with deep cycle battery types like gel, flooded, sealed lead-acid. MPPT technology (tracking efficiency up to 99%) Read more...
Price: US $187.49Related Solar Kits
- Rated Current: 20 A
- Type: MPPT
- Grounding: Negative
The charge controller is compatible with deep cycle battery types like gel, flooded, sealed lead-acid. MPPT technology (tracking efficiency up to 99%) Read more...
Price: US $108.74Related Solar Kits
- Rated Current: 60 A
- Type: MPPT
- Grounding: Negative
The charge controller is compatible with deep cycle battery types like gel, flooded, sealed lead-acid. In User mode, you can set the charging parameters for a custom battery. Read more...
Price: US $499.99Related Solar Kits
- Rated Current: 30 A
- Type: MPPT
- Grounding: Negative
The 30A Rover-Li MPPT charge controller is the latest addition to the Renogy Rover series. It's a Negative Grounding controller with LCD display which shows self-diagnosed errors and parameter data. Read more...
Price: US $169.99
- Rated Current: 20 A
- Type: MPPT
- Grounding: Positive
This 20 A MPPT solar charge controller by Epever has an LCD display for dynamically displaying the system's operating data. Read more...
Price: US $139.99
- Rated Current: 40 A
- Type: MPPT
- Grounding: Negative
SolarEpic 40A MPPT solar charge controller has a heatsink design on the front and rear sides for enhanced heat dissipation so don't expect to see an LCD display on it. But the lack of a display is compensated with RJ45 communication interface which allows you to connect t Read more...
Price: US $159.00
- Rated Current: 30 A
- Type: MPPT
- Grounding: Positive
HQST 30 A MPPT solar charge controller is a Positive Grounding controller, that's to say, you cannot have more than 1 grounding from a positive connector. Read more...
Price: US $131.00
- Rated Current: 40 A
- Type: MPPT
- Grounding: Positive
This is a 40A MPPT charge controller with dual display function: local LCD display and a remote MT-50 meter. The remote meter works with RS485 communication bus interface. Read more...
Price: US $196.99
- Rated Current: 30 A
- Type: MPPT
- Grounding: N/A
Founded in 1975, the Dutch company Victron has been building energy systems since then. The company is known for reliability and an accent on quality. Read more...
Price: US $226.10
- Rated Current: 60 A
- Type: MPPT
- Grounding: Negative
SunnySky is a Chinese negative ground MPPT charge controller manufacturer. The controller's LCD display shows the daily / cumulative power and current generation data also in a form of a plot. Read more...
Price: US $196.00Solar Charge Controller Charging Modes
Solar charge controllers, in general, have 5 working modes:
- Equalization charging - this is not done frequently. Equalization charging is done for maintenance reasons by temporarily overcharging the battery to desulfate its cells. This process maintains the battery cell health increasing battery's longevity.
- Bulk charging - this is typically the first state of battery charging when it has a low charge. It's a quick charging mode when the current is at its maximum. This mode precedes the Boost charging mode.
- Boost charging - this is the most common mode the battery operates in. The boost charging voltage is dependent on the battery type.
- Float charging - this mode is used when the battery is fully charged to prevent it from a damage. In this mode, the battery still charges but the voltage and current are kept low as to match the battery's natural discharge rate
- Low voltage reconnect/disconnect - this mode is used in the charge controllers that support DC loads. Low voltage disconnect appears when the battery's voltage is lower than a threshold value. In that case, the DC load is cut off. Reconnect event occurs when the voltage level is high enough for the load to turn back on.
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