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Solar Charge Controllers FAQ

What is an Off-Grid Solar System?

The solar electric systems associated with the term “solar” are usually simple grid-tied types, with PV modules and an inverter or inverters for converting DC from the modules to AC […]

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What is a Solar Charge Controller?

A solar charge controller is a solar-powered voltage and current regulator. They are used in off-grid and hybrid off-grid applications to regulate power input from PV arrays to deliver optimal […]

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How Does a Solar Charge Controller Work?

The first solar charge controller schematic below (Figure 1) illustrates how a solar charge controller is connected to power a direct current (DC) load, and the second one (Figure 2) […]

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What are the Solar Controller Battery Charging Stages?

Solar charge controllers put batteries through 4 charging stages: Bulk Absorption Float Equalize Figure 3: Multi-Stage Battery Charging For lead-acid batteries, the initial bulk charging stage delivers the maximum allowable […]

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What are the Different Types of Solar Charge Controllers?

The two major types of solar charge controllers are: Pulse Width Modulation (PWM) controllers Maximum Power Point Tracking (MPPT) controllers As shown in the chart below, PWM controllers tend to […]

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What is Different About Morningstar Solar Charge Controllers?

Morningstar solar charge controllers are different from other brands, as you can see in this five-minute video. The high-frequency design allows Morningstar solar charge controllers to react more quickly to […]

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Will Oversized PV Arrays Damage Solar Charge Controllers?

Morningstar’s MPPT solar charge controllers support oversized PV arrays. For example, a 240-watt module won’t damage a SunSaver MPPT solar charge controller and won’t cause it to exceed its rated […]

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Other Solar Charge Controller FAQs

How do I choose a solar controller?

In short, the solar charge controller you choose must be able to support the power requirements of your loads, your battery voltage, and your PV current and voltage inputs. Additionally, you will need to consider whether you need a controller with low voltage disconnect, lighting control, or other features or certifications. Your climate, choice of modules, and price will also determine whether you choose a PWM or an MPPT controller.  A good solar distributor will be able to help you size and configure your modules, batteries and controllers for an optimum system.

Can solar charge controllers monitor data?

Yes, some controllers are equipped to monitor data including battery voltages, system current, absorption and float charging metrics, and faults and alerts.

What temperature ranges do solar charge controllers support?

Many Morningstar solar charge controllers support operating temperature ranges between -40C and +60C.

Are MPPT controllers worth it?

MPPT controllers provide more power, especially in colder temperatures. They can also be used with less expensive 60 cell modules which are usually unsuitable for PWM controllers. Weighing these benefits versus the lower cost of a PWM controller will determine if an MPPT controller is right for your system.

What solar charge controller accessories should I consider?

Accessories to consider are meters, adapters, remote temperature sensors, relay drivers, and other balance of system components.

How can I purchase a solar charge controller?

You can describe what type of charge controller and system you are interested in deploying on our How To Buy page which includes links to a product catalog.

How long do solar charge controllers last?

The longevity of a charge controller depends on the brand and the system environment. The Morningstar Professional Series controllers have a 5-year warranty and many have been in operation for 10 years or more.

What is lighting control?

The ability to program settings on controllers to power on and off lights during the day and evening.  Some controllers have simple controls to turn lights on as dusk and off at dawn. Other controllers have more sophisticated programability to allow for multi-event on/off light switching during a 24-hour period.

What is diversion control?

As batteries become fully charged a controller will direct excess current from the battery to a dedicated load that is large enough to absorb the excess energy, but not too large to cause a controller overload condition.

What is a charge controller's rating?

A charge controller is rated by the current it can accept from a PV array to charge batteries and they battery voltages it will support (e.g. 60 amps for 12, 24, and 48 volt batteries).

What is load current rating?

The rated current that the controller will deliver to loads.

Are charge controllers rated for marine environments?

Some controllers, but not all, are built to withstand the harsh environments associated with boats and marinas.

What battery system voltages do solar charge controllers support 12V, 24V, and 48V systems?

It is important to check the operation manual or datasheet to see what battery voltages your controller supports. Some controllers support voltages from 12, 24, 48 volts and higher, while others might only support 12 volts.

What is self-consumption?

The small amount of power that the charge controller uses up for its own operational purposes rather than delivering to loads and batteries.

Why do you need a solar charge controller?

To regulate power from the PV array to prevent batteries from being overcharged or undercharged, and to prevent the battery from reverse-discharging to the array at night or when there is no power from the sun.

What are other names for a solar charge controller?

Other names for a solar charge controller include: solar panel controller, solar panel charge controller, solar power charge controller, solar controller, solar charge regulator, solar regulator, and charge regulator.

What is a shunt charge controller?

A type of charge controller that short circuits the array to reduce current sent to a battery.  PWM and MPPT controller technology is newer and more prevalent than shunt technology.

What is a controller's Maximum PV Open Circuit Voltage (Voc) limit?

The maximum voltage, listed in the operator manual, that a controller can support. To determine whether your system will operate under this Voc limit you must know the lowest temperature your system will be exposed to, and calculate the voltage produced by your array at that temperature. Exceeding Voc limits will damage your controller.