Professional Installer Frequently Asked Questions

The FAQ provided below is intended as a support resource for professional solar installers. If you are a homeowner or a non-professional DIY installer, please click here to visit the Homeowner FAQ.

You can also review our DIY installer policy here.


Visit your local APsystems website and navigate to the Resources section, then Support. On the Support page you’ll find a form to contact APsystems technical support for your region. They will take a look at the system in question and respond to you shortly.

APsystems does not provide on-site support in most circumstances. Installers can contact our support team using the methods described above. Our technical support specialists  will provide instructions for addressing and resolving site issues. in fact, most issues can be fixed remotely if the system is monitored with an ECU. If you are an installer currently on-site, call your local APsystems support line for help.

Our installer training program is now self-led so we encourage professional installers to watch our instructional videos and read our installation manuals to familiarize themselves with our installation process and best practices. Our support team is available if you should have any questions; simply visit your local APsystems website and navigate to the Support page to contact technical support.

No. APsystems sells exclusively through a network of authorized distributors who sell to professional solar installers. You can find a list of authorized distributors on your regional APsystems website.

You will need to contact a professional solar installer to troubleshoot your system. They will work with us to determine the cause and fix the issue and, if needed, replace any defective units. Often times, troubleshooting requires electrical work or work on the roof. APsystems requires homeowners to work with a professional solar installer to resolve system issues for reasons of safety and liability.


The UID (Unique Identifier) or serial number is a unique 12 digit number assigned to all microinverters.

APsystems uses the industry standard Multi-Contact (Stäubli) MC4 connectors for all DC inputs.

The single phase microinverters (such as DS3, DS3D, YC600, QS1) can be installed in the same circuit. The 3-phase microinverters (such as QT2, QT2D, YC1000) can be installed in the same circuit. Single phase microinvertesr and 3-phase microinverters can’t be installed in the same circuit. Please check spec sheet for maximum units per bus cable.

APsystems is a multi-module input inverter company and does not make a single-module input inverter. If you have an odd number of modules on your installation, simply cap off the unused input with an MC4 dust / sealing cap.

DS3 Series: up to 2 modules ( 2 or 1 modules). it has 2 input channels and per input channel can connect to 1 module. You can leave an input channel empty
DS3D: up to 4 modules ( 4 or 2 modules). It has 2 input channels. And each input channel you need to have 2 modules connected in series. Please note you can not connect a single panel on an input, otherwise the voltage is not enough. You can leave one input channel empty.
QT2: up to 4 modules ( 4/3/2/1 module). it has 4 input channels and per inputchannel can connect to 1 module. you can leave any input channel empty.
QT2D: up to 8 modules ( 8, 6, 4, 2 modules). It has 4 input channels and per input channel need to have 2 modules connected in series. Please note you can not connect a single panel on an input, otherwise the voltage is not enough. But you can leave any input channel empty.

For the input channels that are using the same MPPT, we recommend you to connect to the same modules with the same direction. For the input channels that have independent MTTP, you can connect to different type of modules.

Yes, APsystems provides module compatibility calculator via our online design guide which can be found by visiting our library.

The modules can work with microinverters as long as the voltage and current are not exceeding. Larger power modules will not damage the microinverter. Normally it is recommend to have DC/AC around 1.3. Normally the power that is generated by the oversizing PV is more than the power lost from peak clipping.

Please refer to the datasheet and local regulations.

No. The microinverter can only produce power when connected to the grid, hence it’s a grid-tied inverter.

This is highly dependent on local regulation (not valid in France, US or Canada).

You can view LED information in the installation instructions for your microinverter by visiting our library. You can learn about them in the APsystems installation videos on our YouTube channel

Apsystems microinverters have ground wire in the cable, and also the washer to be contacted to the mounting systems for the grounding. But some areas do require separate grounding. Please install based on your local electrical regulation.

Yes, a galvanic transformer is embedded in each microinverter.

No need for special configuration, the APsystems inverters will turn on and produce power once it has one or more DC inputs, proper AC, proper frequency and has waited the 300 second dwell time.

The star washer, or Weeb, is preinstalled and designed to electrically bond the inverter to the rails for grounding. Please check with your local regulations or AHJ for proper grounding for your installation.

Different regions have diffent standards for the DC Arc-Fault protection. Apsystems microinverters have the certificagted of the related countries. For the details of the certificates, please find the Certificate under the Library.

Absolutely, APsystems microinverters have been installed in harsh environments, operating normally for more than a decade. We also ensure our designs pass HALT testing which includes; damp heat, humidity freeze, salt mist and UV. Our dual module and quad-module designs have also been independently tested by DNV-GL.

Both DS3 series and QT2 series are compliant with local regulations regarding RPC.

Yes, APsystems strongly recommends to install a whole-house surge protection device at the dedicated meter box. Please check with your local regulations or AHJ.

No, APsystems does not offer an off-grid product at this time. All APsystems products comply with IEEE-1547 anti-islanding standard.

DS3 has 2 input channels and 2 MPPTs. Each input channel can connect to 1 module. And per input channel has an independent MPPT.
DS3D has 2 input channels and 2 MPPTs. Each input channel can connect to 2 modules in series. And per input channel has an independent MPPT.
QT2 has 4 input channels and 2 MPPTs. Each input channel can connect to 1 module. And 2 input channels have the same MPPT.
QT2D has 4 input channels and 2 MPPTs. Each input channel can connect to 2 modules in series. And 2 input channels has an independent MPPT.

Apsystems microinverters are distributed inverters. they are not generating electrity if not connected to the grid, and they have anti-island function.

1. Please check if the operation voltage range and frequency range is matching the grid requirement
2. Please check if the breaker, AC connector, Y connector or T connector is well connected. And measure Y or T connector to see the the voltage at the Y/T connector is normal.
3. For Y cable, try to adjust the Pin as shown in the picture
4. after the above steps, if the problem still exist, please contact our customer support team.

It is possible that there is no sunshine at that moment. If there is no sunshine then there is no DC input voltage. Then the light of the microinverter is not showing any color.


Visit your local APsystems website and navigate to the Resources section, then Support. On the Support page you’ll find a form to contact APsystems technical support for your region. Make your request on the form or send an email to APsystems support in your region to reset / change username, email address or your login password.

No, nothing is wrong with your inverter. The power output of the module is typically +/- 10% from module to module. In addition, the communications ECU / gateway 'polls’, or asks the inverters for their power production every five minutes one-by-one, and the polling time may differ by a few minutes per solar panel so variations will happen from time-to-time. Shading can also vary module by module.

In case of one or more panels is showing NC, a few checks can be done: 1. Make sure the ECU is connected to the power; 2. Make sure the UID of microinverters have been entered to the ECU correctly and have been synchronised; 3. Connecting can take about 10 minutes. when there are more microinverters, it can take more than 30 minutes; 4. Make sure the light on the microinvertr is green; 5. Make sure the ECU is close to Microinverters. If all of the above doesn’t work, please contact our customer support team.

Verify that the AC breakers are in the on position, and power is connected all the way to the end of each branch circuit and that panels are clean

The APsystems ECU gateway collects a snapshot of data from each microinverter on the DC side every five minutes and is carefully designed to minimize network traffic and give a most possible accurate production in their operating environment. The utility company utilizes a revenue grade meter which constantly measures power production on the AC side and as such collects data in real-time. The EMA is intended to demonstrate power production, not record revenue grade data. The energy production numbers shown in the EMA are an estimate based on these infrequent intervals and will often be different than those shown in your utility bill for reasons of monitoring frequency, accuracy and what’s being measured (AC vs DC).

Green: The system is functioning normally.
Yellow: It could mean:
1. Some microinverter communication has been interrupted since the beginning of day or…
2. Some microinverters have not been properly registered or…
3. Some microinverters have low power production (abnormal behaviour or weak/lack of sunlight)
Consider checking the details of the site in the EMA and verifying microinverter UID registration.
Red: ECU disconnected from internet.
Black/Gray: The system has never reported production data. This system could be offline. If it should be online, verify that the ECU has been installed properly and connected to the internet.

The ECU 'polls’ each microinverter every five minutes for a total of twenty polls per hour and data pushed to the EMA portal every 15 minutes.

Green: solar production (always positive)-measured
Grey: grid (positive or negative): imported or exported – measured
Blue: consumption of electrical appliances in the household -calculated (always positive) if the green curve is negative, please reverse the direction of the CT measuring the PV production, if the blue curve is negative, please reverse the direction of the CT measuring the grid import / export

Simply login to your installer account, navigate to the installation, click on 'Device Replace’, click on 'Replace’, enter the new ECU / Microinverter serial number and click 'Submit’.

See our EMA User guide in our library here.

No problem, module power depends on sun irradiance and module temperature. Click here for more information.

Simply login to your installer account and navigate to the 'User Registration’ section and follow the self-guided prompts to complete the registration. To view the EMA User Guide, visit our library.


Krok 1: Włącz ECU

Krok 2: Naciśnij przycisk AP na ECU

Krok 3: Zeskanuj kod QR poniżej, by pobrać ECU Manager jeśli jeszcze tego nie zrobiłeś

Krok 4: Otwórz ECU Manager, kliknij“Dostęp lokalny” w prawym dolnym rogu

Krok 5: Połącz się z siecią WIFI ECU za pomocą ECU ID (numer użytkownika), wpisz hasło: 88888888 aby zalogować się do ECU

Uwaga: Jeżeli nie możesz znaleźć sieci WIFI ECU, proszę spróbuj ponownie. Należy umieścić ECU blisko routera. Nazwa sieci WIFI jest taka sama jak pierwszy UID (numer użytkownika) podany z tyłu ECU

Krok 6: Wróc do aplikacji ECU Manager, kliknij „Obszar roboczy” i wybież „Sieć ECU”

Krok 7: Wybierz dostępny router WIFI by połączyć się bezprzewodowo

Jeżeli połączenie zostanie nawiązane, obie diody LED na ECU zaczną świecić się na zielono.

The ECU-R and ECU-C can be connected to the internet via hardwire ethernet cable or Wi-Fi connection. If utilizing the hardwire ethernet cable (the preferred and most reliable method) simply connect the Ethernet port on the ECU-R or ECU-C to an open Ethernet port on the router or switch. If utilizing the built-in Wi-Fi, access the ECU APP and navigate to the Settings tab, WLAN and search for available Wi-Fi, select the homeowner’s router, enter the password and hit OK. See our YouTube video on the ECU-R for instructions on how to do this.

The APsystems Zigbee communication works at 2.4GHz, the same frequency as the Wi-Fi in your home or business.

Be sure you have a line-of-site distance of no more than 50m (150 ft), ensure that the Zigbee antenna is installed properly, the serial numbers of the inverters have been loaded properly and the inverters are compatible with the ECU.

To view installation instructions, visit your regional APsystems website and navigate to Resources > Library. You can also view APsystems installation videos on our YouTube channel.

To view installation instructions, visit our library. You can also view APsystems installation videos on our YouTube channel

No, the microinverters must be scanned using the ECU APP and synced with the ECU-R/C in order for the microinverters to communicate and demonstrate power production.

Please verify that you have plugged in the ethernet port and not the RS485 port of the ECU. Also verify that you are plugged in directly the router and not through a switch or a EOP (Ethernet over Powerline) device. Lastly, you may want to try another ethernet cable, as cables do go bad from time-to-time. [for commercial systems you can utilize the static IP feature using the ECU APP, determined by the IT manager of the business]

It can connect to max 100 microinverters. We recommend to connect 80 microinverters for the optimized performanced. Try to position the ECU close to the microinverters and try to avoid obstacles or other electrical equipment.

Yes, you can do this function with the ECU-C gateway and configuring the ECU-C „Zero Export” function. See our product manual and our installation and configuration guide here.

You can learn the step-by-step procedure for utilizing the 'zero export’ feature of the ECU-C by visiting our library.

Move the screen from direct sunlight, reboot and observe. If that doesn’t fix it, send an email to your local APsystems technical support team for support.

The -W or -Web means that the ECU does not have a proper internet connection. Please reboot the ECU, change the cable or check the internet connection. If this does not fix the issue, please contact your APsystems local technical support team for support.

ECU-R focus on residential installations. And ECU-C is for commercial installations. And the ECU-C has redundant energy control function.

Yes, you can buy extensions from any third-party supplier. Just look for a Wi-Fi antenna, 2.4GHz with SMA male/female connectors. Maximum length of 20m.

No, please use the APsystems 80A and 200A CTs. They are available at your local distributor

APsystems allows up to a maximum of 30 meter extension of the factory CTs using standard CAT 5e cable, which can accommodate up to four CTs per cable.

No, there is no local web access to the ECU-R

Both ECU-R and ECU-C are using international standard SunSpec Modbus protocol. It can be downloadeded from te SunSpec.

No need. The maximum number of units and the recommended number of units indicated by us are to ensure the stability of system communication as much as possible

Both ECUs can communicate with the inverters via Zigbee up to 76 meters with direct sight and can utilize Wi-Fi (WLAN) to connect to the site owner’s wireless router up to 9 meters with direct sight, however this last point depends primarily on the site owner’s wireless router’s capability.

Please check the ECU-C user manual under the chapter Hardware installation.


EMA APP is designed for APsystems microinverters system owners and DIY users.

The EMA Manager Manager APP is a tool for professional installers to use in the initial set up of your system.


APsystems inverters are agnostic and will function perfectly with all AC coupled storage solutions on the market today. You can use our APsystems Storage Solution for storage systems.

APsystems’ microinverters are designed to be grid-tied only. APsystems does not support using microinverters in conjunction with a generator on a closed-loop system. The APsystems warranty policy clearly states that microinverters used with a generator are not covered.

Contact your local electronic waste treatment facility.

APsystems does not provide electrical drawings or permitting plans for submittal to the utility company.

Yes, the ECU has an offline monitor function (traditionally used by installers) that can be used for customers that do not have internet. The offline monitoring feature can be accessed by holding the AP button on the side of the ECU for approximately two seconds and then releasing, connecting your hand phone via the Wi-Fi (ECU-R_216xxxx) broadcast by the ECU and then opening the ECU APP – navigating to the Data tab to see Real Time Data, Power and Energy. (Note about limited memory – check with installer today). Note: APsystems always recommends that the ECU be connected to the internet (hardline or GSM router) to ensure that the ECU and inverters can be updated to the latest software and firmware for the lifetime of the system.

No, APsystems does not offer that feature and neither do current string inverters due to the updated NEC Rapid Shutdown requirements.

APsystems is featured in many of the popular PV simulation programs today including; HelioScope, PVsyst, PVSol.

The API is only available for certain installers to develop their applications. The API is a REST API and delivers data in JSON format via HTTPS. The API is categorized into two-level data:
• System Details API
• ECU-level Data API
Access to the API will require unique user credentials provided by APsystems on a case-by-case basis. Contact your APsystems representative for more information.
Current calls are as follows:
• Current Power
• Daily Production
• Monthly Production
• Yearly Production
• Lifetime Production

No, the APsystems microinverters are designed to work with today’s solar modules, not wind turbines.

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