MPPT SMPPT10D, SMPPT20D, SMPPT30D Operation Manual

SMPPT

Solar Charge Controller with

Maximum Power Point Tracking

10A/20A/30A 12V/24V

Installation & Operation Manual

SMPPT Installation & Operation Manual Version 1.0

1

SMPPT Installation & Operation Manual Version 1.0

2

Dear Consumer：

Thank you very much for using our product! We will offer you the

permanent and reliable service for your solar system!

The manual gives important recommendations for installing and
using the MPPT controller. Please read the manual carefully and
thoroughly before using this product.

SMPPT Installation & Operation Manual Version 1.0

3

1. Safety Instructions

(1) The controller is only designed to be connected to the off-grid solar

system. It offers the management of charging and discharging for the

lead-acid battery of flooded, gel and AGM chemistries from 12V to 24V

nominal only. Do not connect this controller to other system, such as

mains supply and windmill generator.

(2) The controller is intended for indoor use only. Protect it from direct

sunlight and place it in a dry environment.

(3) Batteries generate explosive gases during normal operation. It is

important never allow a spark or flame in vicinity of battery.

(4) Be sure to always keep children away from batteries and acid!

(5) Do not disassemble the MPPT controller, it does not have any

user-serviceable parts.

(6) The controller warms up during normal operation. Do not touch the

heatsink at the bottom of the controller.

Note:

It is important that the battery is fully charged frequently (at least

monthly). Otherwise the battery will be permanently damaged.

2. MPPT Controller Instructions

2.1 Overview

SMPPT solar charge controller is multi-stage Maximum Power Point

Tracking (MPPT) photovoltaic battery charge controller with our own

technology. It’s main topology adopts in Buck conversion circuit, and uses

MCU to adjust the solar panels working point intelligently in order to make the

solar panels output its maximum power. When the circumstances change, the

working point of solar panels deviate from the maximum power point, MCU will

adjust the solar panels working point based on MPPT calculation to make the

solar panels back to the maximum power point again(refer to Chapter 2.4

about MPPT technology introduction). Compared with PWM controller, MPPT

controller can increase the output power of solar panels by 5%~30%. The

output power increasing proportion is affected by the factors such as solar

panels property, humidity and light intensity. The controller uses wall-mount

installing (refer to Chapter 4.1). Connecting terminal makes the wiring area

bigger and wiring loss less.

SMPPT Installation & Operation Manual Version 1.0

4

2.2 Structure

Figure 2-1: Controller Structure Diagram

2.3 Functions

(1) Maximum Power Point Tracking technology

The controller uses Buck conversion circuit and MCU technology to track

the maximum power point to implement the maximum output power of solar

panels in different illumination intensity and temperature. The MPPT

algorithm increases efficiency of your PV system and decreases the

quantity of solar panels.

(2) Multi-stage Charge Control

The starting charging voltage of battery is different, the controller will use

the different charging strategies to finalize the charging process. When

starting charging voltage of battery is lower than 12.6V (for 12V battery),

battery will go through three stages as Bulk, Absorption and Float charging.

When starting charging voltage of battery is higher than 12.6V (for 12V

battery), battery will go through two stages as Bulk and Float charging.

Bulk Charge:

The controller charges the battery by its maximum output current. It is at

maximum power point tracking state at this phrase.

Absorption Charge:

The controller begins to limit the charging current to make the battery

voltage fixed at a settled absorption voltage (this voltage has temperature

compensation) for 2 hours. It increases the charging saturation level of

⑤

① LCD Display Screen

② Temperature Sensor

③ Button

④ USB Output

⑤ Solar Terminal Block

⑥ Battery Terminal Block

⑦ Load Terminal Block

⑥ ⑦

① ② ③

④

SMPPT Installation & Operation Manual Version 1.0

5

battery and prevents battery from leaking gas, and this can increase the

lifetime of battery.

Float Charge:

The battery is at saturation state, and the controller charges the battery at a

trickle current to make the battery voltage fixed at the settled float charging

voltage (this voltage has temperature compensation).

(3) Charge Voltage Temperature-compensated

The controller will compensate the Float charging voltage and Absorption

charging voltage by -4mV/Cell/°C based on the current battery

temperature.

For 12V battery, the compensated voltage U=(t-25)*6*(-0.004)V

For 24V battery, the compensated voltage U=(t-25)*12*(-0.004)V

(4) Discharge Control

The controller monitors the battery voltage all the time. The load will be

switched off when the voltage less than the Low Voltage Disconnect (LVD)

point, and it won’t be switched on until the voltage more than the Low

Voltage Reconnect (LVR) point.

(5) Protection against Reverse Connected Battery

Connecting the battery to the controller by reversed polarity (under the

circumstances of solar panels disconnected) will not damage the controller.

The controller will work normally after connecting with correct polarity.

(6) Protection against Reverse Connected Solar Modules

Connecting the solar modules with the controller by reserved connection

will not damage the controller. The controller will work normally after

connecting with correct polarity.

(7) Reverse Current Protection

The controller prevents reverse current from flowing into the solar modules

12.2V

Absorption

Float

Figure 2-2: Three-stage Charge

t

2h

U

Bulk

12.7V

Float

Figure 2-3: Two-stage Charge

t

U

Bulk

SMPPT Installation & Operation Manual Version 1.0

6

at night. An additional reverse current diode is not required.

(8) Overtemperature Protection

If the temperature inside the controller becomes too high, then the

controller will stop charging to the battery, and it will restart charging the

battery again when the temperature decreases to a certain value.

(9) PV Overvoltage Protection

If the input voltage of solar panels exceeds the maximum voltage permitted

by the controller, it will enter into protection state automatically and stop

charging. When the input voltage recovers to the normal range, the

controller will start charging again.

(10) Current-limited for Excessive Charging Current

If the permissible charge current is exceed, the controller will deviate from

the maximum power point to limit the output current to prevent the

controller being damaged.

(11) Load Output Overload Protection

If the permissible load current is exceed, then the load output is switched

off. The overload current vs. duration shows as follows:

Rate of Current Duration (s)

1.2Irate ≤I< 1.5Irate

60

1.5Irate ≤I< 1.8Irate

10

I≥ 1.8Irate 0.2

Note:

Irate=10A/20A/30A, nominal load current

The controller restarts the load every 6 minutes automatically, but the user
can also restart the load by the Load key（Load key chapter 5.2.2）.

2.4 MPPT technology Instructions

Solar panels are nonlinear materials, and the output power is mainly

affected by illumination intensity, solar panels temperature and load

impedance. When the illumination intensity and solar panels temperature are

fixed, the output power of solar panels is only affected by load impedance.

Different load impedance will make the solar panels work at different point and

put out the different power. The following figure will mark the four working

points A, B, C, D, and the working point features as follows:

Working point D:

SMPPT Installation & Operation Manual Version 1.0

7

Output voltage is 22.3V, output power is 0W. This point is the open circuit

point of solar panels.

Working point C:

Output voltage is 0V, output power is 0W. This point is the short circuit

working point of solar panels.

Working point A:

Output voltage is 13V, output power is 74W. This working point is the state

when using normal controller, and the solar panels voltage is clamped to

13V by battery.

Working point B:

Output voltage is 17.6V, output power is 92W. This point is the state when

using MPPT controller. Because of using power conversion technology, the

solar panels voltage is not clamped by battery and still works at maximum

power point.

Compare working point A & B, it is easy to find using MPPT controller can

increase the using efficiency of solar panels. Compared to normal controller,

MPPT controller can generate more power.

Figure 2-4: Voltage-Current Curve