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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 power output to run electrical loads and charge batteries. Solar charge converters are also commonly called solar charge regulators. Solar charge controllers maintain batteries at their highest state of charge without overcharging them to avoid gassing and battery damage.

> Read more about solar charge controllers.

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What are the proper DIP switch / charging settings for my battery type?

Morningstar classifies batteries into five categories: gel, sealed, AGM, flooded, and L-16. However, the actual specifications of a specific battery may vary from what is programmed into the charge controllers. Morningstar recommends that customers check with the manufacturer of the battery and pick the setting that is most closely related to those specifications, as the ‘battery type’ designation can sometimes be subjectively defined.

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Can I specify my own charging set-points?

Yes. Controllers with communication ports can be custom programmed using our free MSView software available on our technical support page.

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Using a DC power supply as a PV panel substitute?

Morningstar PWM controllers are not designed to properly process input from a DC power supply. This type of input is not recommended and is connected at the user’s risk. DC power supplies have considerably more output capacitance than PV panels and connecting a DC power supply to a Morningstar PWM controller may cause excessive heating and premature failure.

MPPT controllers can be used for this application with no issue.

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What is the Modbus protocol?

From the FAQ at http://www.modbus.org:

MODBUS® Protocol is a messaging structure developed by Modicon in 1979, used to establish master-slave/client-server communication between intelligent devices. It is a de facto standard, truly open and the most widely used network protocol in the industrial manufacturing environment. It is implemented by hundreds of vendors on thousands of different devices in order to transfer discrete/analog I/O and register data between control devices.

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What are acceptable dump/diversion loads?

Diversion loads acceptable for use are water heating elements and air heating elements (i.e. purely resistive loads). DO NOT use light bulbs, motors, inverters, refrigerators, or other electrical devices for diversion loads. These loads will sustain damage or cause the controller to disconnect the load (leaving the system unprotected from overcharge). Only heating elements should be used. Diversion load sizing is addressed in your diversion controller’s manual.

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Do I need a fuse between the batteries and the charge controller?

Yes. A battery fuse is required to protect the battery cabling in the event of a short circuit condition.

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Can I mount the controller horizontally?

Morningstar controllers have been designed to mount vertically. This is the orientation in which the heatsinks are most effective. Mounting the controller horizontally will reduce its passive cooling efficiency and may risk overheating the unit. Every effort should be made to mount the controller vertically. Mounting horizontally is not recommended.

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What is the function of “Load” port on the controller?

The Load terminals provide power to DC devices such as fans, compact fluorescents, radio equipment, etc. When the battery discharges too low, the controller will disconnect the dc loads to prevent over-discharge (LVD equipped units only) and automatically reconnect when the battery has sufficiently recharged. The total load draw through the LOAD connection should be within the nameplate rating of the controller. Inverters of all sizes should be wired directly to the battery terminals. The load connection is optional and can be left disconnected if not needed.

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Will other charging sources backfeed into my controller?

Other charging sources can be used in parallel with the Morningstar charge controller; you do not need to isolate the controller from the battery. For best performance when using other charging sources, ensure the charging source and Morningstar controller are set to charge to the same (or close) voltage. If the supplemental charging source is set to a higher charging voltage than the Morningstar controller, the Morningstar controller may go into a fault state temporarily when the battery voltage rises higher than the controller’s setpoint. The controller will automatically recover from this state when the battery voltage drops to a lower level.

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What is the maximum input (solar) voltage rating of the ProStar 12/24V controller?

The maximum input voltage rating for the ProStar is 58Vdc. If using the ProStar to charge a 12V battery, the input must be a nominal 12V off-grid solar panel with a Voc < 30 Volts. Do not charge a 12V battery with a 24V solar panel. The solar panel will operate too far off its power point (very inefficient) and voltage spikes during regulation will damage the ProStar. Damage resulting from an array >20Voc in a 12V battery bank system will NOT be covered under warranty.

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Do Morningstar controllers prevent reverse discharge at night?

All Morningstar controllers prevent reverse discharge back to the solar array at night. No external diodes are required on the solar input of a Morningstar controller.

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Can I parallel the AC outputs of two SureSines for more power?

SureSine inverters cannot have their AC outputs paralleled with other inverters. The two SureSines would not be able to phase align their AC output waveforms, resulting in a very messy AC signal damaging to AC equipment or damage/malfunctioning of the SureSine inverters.

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