EPEVER ViewStar-AU Series-PWM Solar Charge Controller Review

Updated: Nov 3, 2019

A solar charge controller is the most important component in virtually all solar power systems that utilize charging battery. It’s the heart of the system which regulates the power going from the solar panels to the batteries.

In this article, I want to share inside look at EPEVER ViewStar-AU Series PWM Solar charge controller. I have purchased the VS1024AU model , which is for 10A and 12V/24V system. There are other variant also : 12/24V,12/24/36/48VDC 10-60A. Here I will discuss about the VS1024AU model.

ViewStar-AU Series ( VS1024AU - 10A 12/24V) :

The controller is PWM charge controller with built in LCD display with option for charging various lead acid battery type and multiple load control functionality.


Rated voltage : 12V / 24V DC Auto detect

Rated charging current: 10A Max Input Power: 12V @ 120W | 24V @ 240W

Max. PV open circuit voltage: 50V (45V at 25℃ temperature) Battery type: Sealed(Default) / Gel / Flooded 3-Stage PWM charging: Bulk, Boost/Equalize and Float Battery voltage range: 9V~32V USB output: 5VDC /2.4A (Total) Net weight: 1.02kg

Outer Look and Build Quality :

The enclosure is made up with high quality plastic and IP30 ingress protection. On the front side , there is a large LCD display to displaying various critical parameters related to Solar PV , Battery and load. On the top right side there are two USB port to charge smartphone or tablets. Just below the LCD screen there are two buttons : Menu and Set. Below the buttons, six screw terminals are given for connecting Solar Panel , battery and load. Each terminal is clearly indicated with specific icons.

On the back side, the enclosure is covered by a thick aluminum sheet and is mounted by 4 diagonal screws. This is used as a heat sink for the MOSFETs inside the controller.

At the bottom left side, you will notice a small port which is for connecting the remote temperature sensor (RTS). Close to the RST port, opening for inserting wires to the 6 screw terminals is there. The terminals are UL and VDE certified. On the right side there are 4 small holes, I could not find out its purpose. The enclosure is well engineered for air passage over the aluminum sheet to ensure faster cooling.

There are four holes at the corner to mount the controller on wall or any other flat surface.

Testing the Charge Controller :

To test the controller, I have used a 12 volt sealed lead acid battery , 20 Watt Solar Panel and a 3 Watt LED as load. As soon as the battery is connected to the controller, the LCD start to display the parameters like charging status , voltage, current , Energy (kWh) , Temperature , load status and load timer.

The display details is shown in the below table :

Support Multiple Battery Type :

This controller is suitable for charging the widely used lead acid battery type like : Sealed,

Gel and Flooded type. You can select the battery type from the menu button. Under Battery Voltage interface, press SET button and hold on 5 secs then enter into the interface of Battery type setting. After choosing the battery type by pressing MENU button, waiting for 5 secs or pressing SET button again to modify successfully.

Battery Temperature Monitoring :

The controller is equipped for battery temperature compensation function.Note that, you have to plugin the remote temperature sensor ( RST). The temp. sensor is not included with the charge controller you have to buy it separately. The model number is RTS300R47K3.81A. The default temperature setting is 25 deg C. You can also switch the temperature unit from Celsius to Fahrenheit from the menu. You can buy the RTS from Amazon.

Display Accuracy :

To check the accuracy of the parameters ( voltage, current and kWh) display on the LCD , I used my PortaPow. The displayed valued on the controller is quite accurate to the measured value by my PortaPow. I have also tested with my Extech Multimeter, the accuracy is quite good.I am really satisfied with result.

Self Power Consumption :

The self power consumption of the controller is 10.6 mA which is very close to the declared value ( 9 mA ) in the manual. Note that, the power consumption is 15 mA when the back light of the LCD is ON.

Multiple Load Control :

The controller have multiple load control options. There are two timer to precisely set the timing of load ON and OFF. You can control the load manually or automatic. The default setting for the first timer is 117 ( manual) and second time is 2n. You can set the time from load mode setting interface. I have checked the load load control functionality, it works as promised. The details timer setting is given in the table below:

Testing USB Port :

The USB port output rated for 5V /2.4A (Total) . To test the USB port, I have used an electronic load. I set the load to 5V and 2.1 A, there is no voltage drop observed. It succfully deliver the rated output.

Teardown Of VS1024AU :

I was very curious to see the internal parts of this Controller. Once you unscrew the 4 screw on the back panel, the PCB will accessible.First you can see that 3 MOSFETs are heatsinked to the backside aluminum plate by a heat transfer tape.

Just below the main PCB, you will find the PCB for the LCD display. The LCD controller PCB is mounted over enclosure's standoffs with the help of 4 screws. The main PCB is connected to the LCD PCB by a ribbon cable.

Main PCB :

The PCB looks very neat and high quality, all the components are soldered perfectly and the components used are also genuine. The main components used are Microcontroller , MOSFETs, regulators, comparators, transistors,diodes, resistors, capacitors and battery fuse . Most of the components are from reputed manufacturer.

LCD Controller PCB :

The LCD controller PCB have display driver and the two USB port with its associated components like capacitor and inductor. The components are isolated from the display unit by a grey colored insulation cube ( It is my guess).

Components Used :

The main processor used in this charge controller is a 32 bit ARM microcontroller from STMicroelectronics with model no - STM32F 030C8t6 .

There are 3 n channel MOSFETs inside the controller. Two are used for charge regulation from Solar panel to battery and the third one is for load control. The MOSFETs used are from STMicroelecrtonics which are rated for 68 V and 110 A with a very low on-resistance of 0.0065 Ω. Model no is STP110N7F6.

It also uses Quad differential comparator - LM2901 and Dual differential comparator -LM2903 which are from the reputed manufacturer Texas Instrument.

Final Decision :

The Charge Controller is working with charm for me . EpEver keeps all the promises given in its manual. I am really satisfied with this Charge Controller. The price of this controller is little bit higher than the other cheap Chinese charge controller available on the market. But I will recommend to spend this little amount, you will never be regretted in the long term.

Thank you for reading this article. If you like my writing, please share it among.

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