How to choose Solar Charge Controller?

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Solar Charge Controllers mainly are divided into 2 classes: MPPT and PWM, and you can find the description of the difference between these 2 in the last part of this page.

Both PWM and MPPT charge controllers are widely used in various kinds of solar DC power systems, like solar street light, DC power kit, RV kit, communication DC station, backup power station and so on. Years before, solar DC power products were only being used in industrial projects, and not many people took them for self use, but now more and more people have already accept solar power and begin to use solar products in their personal lives.

If you are interested in solar charge controller, but not a profession in solar DC area, then please read the below content for more understandings:

Safety Use Tips on Solar Charge Controllers

Once you’ve got a solar charge controller, no matter what brand it is, we need to review some tips on charge controller use safety.

1

Always remember to review the charge controller manual thoroughly before attempting installation. Not only on the electrical parameters parts, but also on the charge controller wiring instruction.
2

Beware of any nearby electrical equipment that may interfere with installing this device. Solar charge controller is DC appliance, and please never plug in or use it for any AC source.
3

Solar panels can generate high voltages and currents, make sure your solar panels are completely covered from sunlight during installation. It is recommended that installation be performed by a qualified electrician.
4

Connecting wires to this device can generate sparks, please wear proper insulation gear while installing this device.
5

To avoid damage to the battery or controller, use proper fuses in wiring. Please do not hesitate to contact the professions if you need help with fuse sizing.
6

Always keep children away from this device. If possible, please don’t allow non-professions to touch this device or the whole system.
7

Be certain to use the correct gauge of wire, see below for a table of recommended wire size for various current loads.

Solar Input Current	5A	10A	20A	30A	40A	60A
Wire SIZE (mm²)	1.5	2.5	5	8	10	12
Wire AWG	15	13	10	8	7	6

Safety Use Tips on Solar Charge Controllers

If you are now using a HeliosNE charge controller, then sometimes you may find some error code may appear in the LCD screen. That means there is something wrong with the system, and we need to check and do the quick trouble shootings as what in the below diagram:

Error	Description & Quick Troubleshoot
Battery Over-discharged	Battery Over-discharged Battery voltage is too low. DC load will be turned off until battery re-charges to recovery voltage.
Battery Over-voltage	Battery voltage has exceeded controller limit. Check battery bank voltage for compatibility with controller.
Load Short Circuit	DC load short circuit.
Load Overload	DC load power draw exceeds controller capability. Reduce load size or upgrade to a higher load capacity controller.
Overheating	Controller exceeds operating temperature limit. Ensure the controller is placed in a well-ventilated cool, dry place.
Solar Over-amperage	Solar array amperage exceeds controller rated input amperage. Decrease the amperage of solar panels connected to the controller or upgrade to a higher rated controller.
Solar Over-voltage	Solar array voltage exceeds controller rated input voltage. Decrease the voltage of solar panels connected to the controller.
Solar Reverse Polarity	Solar array input wires connected with reverse polarity. Disconnect and re-connect with correct wire polarity.
Battery Reverse Polarity	Battery connection wires connected with reverse polarity. Disconnect and re-connect with correct wire polarity.

For further questions, or you need to talk with our engineers, then please email us or leave messages in the website.

Charge Controller Basic Knowledge FAQ

1.What’s the difference between PWM and MPPT charge?
Many solar power system users may have headache about how to choose a controller for their solar power systems, PWM or MPPT? Commonly, we have a few guidelines for this:
- 1) If your system is very small, like PV lower than 100W, PWM may be better. However, if you system has a high demand on charge amount, you also can choose MPPT, like some solar light with high LED power.
- 2) If your PV array’s voltage is much higher than the battery bank, like 12V battery, but 30V PV system, then no doubt you need to use MPPT. Almost all thin film PV arrays (very high voltage) have to use MPPT.
- 3) If you use Sun Power cells assembled modules, then it’s better to use MPPT.
- 4) If your PV module voltage is very close to the battery voltage, like 30V module to a 24V battery bank, or 18V module to a 14.8V lithium battery, PWM charge may have an improved charge efficiency, sometime could be up to 90%. * please notice that the PV voltage shouldn’t be lower than the battery charge voltage all the time while it’s working.
- 5) If the PV voltage is very close to the battery bank voltage, then MPPT may not work very well, and in some cases like that, MPPT charge may never begin in the whole charge time.
- 6) If you still have no idea about how to choose, then please contact us.
2.How to choose PWM or MPPT controller for my solar DC power system?
Many solar power system users may have headache about how to choose a controller for their solar power systems, PWM or MPPT? Commonly, we have a few guidelines for this:
- 1) If your system is very small, like PV lower than 100W, PWM may be better. However, if you system has a high demand on charge amount, you also can choose MPPT, like some solar light with high LED power.
- 2) If your PV array’s voltage is much higher than the battery bank, like 12V battery, but 30V PV system, then no doubt you need to use MPPT. Almost all thin film PV arrays (very high voltage) have to use MPPT.
- 3) If you use Sun Power cells assembled modules, then it’s better to use MPPT.
- 4) If your PV module voltage is very close to the battery voltage, like 30V module to a 24V battery bank, or 18V module to a 14.8V lithium battery, PWM charge may have an improved charge efficiency, sometime could be up to 90%. * please notice that the PV voltage shouldn’t be lower than the battery charge voltage all the time while it’s working.
- 5) If the PV voltage is very close to the battery bank voltage, then MPPT may not work very well, and in some cases like that, MPPT charge may never begin in the whole charge time.
- 6) If you still have no idea about how to choose, then please contact us.
3.How to make the best and safe use of MPPT charge?
Many solar power system users may have headache about how to choose a controller for their solar power systems, PWM or MPPT? Commonly, we have a few guidelines for this:
- 1) If your system is very small, like PV lower than 100W, PWM may be better. However, if you system has a high demand on charge amount, you also can choose MPPT, like some solar light with high LED power.
- 2) If your PV array’s voltage is much higher than the battery bank, like 12V battery, but 30V PV system, then no doubt you need to use MPPT. Almost all thin film PV arrays (very high voltage) have to use MPPT.
- 3) If you use Sun Power cells assembled modules, then it’s better to use MPPT.
- 4) If your PV module voltage is very close to the battery voltage, like 30V module to a 24V battery bank, or 18V module to a 14.8V lithium battery, PWM charge may have an improved charge efficiency, sometime could be up to 90%. * please notice that the PV voltage shouldn’t be lower than the battery charge voltage all the time while it’s working.
- 5) If the PV voltage is very close to the battery bank voltage, then MPPT may not work very well, and in some cases like that, MPPT charge may never begin in the whole charge time.
- 6) If you still have no idea about how to choose, then please contact us.
4.How to find and fix the problems with solar DC power system?
Many solar power system users may have headache about how to choose a controller for their solar power systems, PWM or MPPT? Commonly, we have a few guidelines for this:
- 1) If your system is very small, like PV lower than 100W, PWM may be better. However, if you system has a high demand on charge amount, you also can choose MPPT, like some solar light with high LED power.
- 2) If your PV array’s voltage is much higher than the battery bank, like 12V battery, but 30V PV system, then no doubt you need to use MPPT. Almost all thin film PV arrays (very high voltage) have to use MPPT.
- 3) If you use Sun Power cells assembled modules, then it’s better to use MPPT.
- 4) If your PV module voltage is very close to the battery voltage, like 30V module to a 24V battery bank, or 18V module to a 14.8V lithium battery, PWM charge may have an improved charge efficiency, sometime could be up to 90%. * please notice that the PV voltage shouldn’t be lower than the battery charge voltage all the time while it’s working.
- 5) If the PV voltage is very close to the battery bank voltage, then MPPT may not work very well, and in some cases like that, MPPT charge may never begin in the whole charge time.
- 6) If you still have no idea about how to choose, then please contact us.

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