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.

Yes, please see our Homeowner / System Owner FAQ here

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 microinverters 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. Please see the question on “How many solar modules can I connect to each type of microinverter?

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 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 or AHJ.

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.

QT2 and QT2D can have direct 380V-400V output, they are suitable for both Delta and Wye grid.

APsystems microinverters are distributed inverters. they are not generating electricity 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.


The Power Conversion System can also be thought of as a battery inverter. The inverter allows the DC battery to interface with the grid.

It comprises of a APsystems Power Conversion System and Compatible DC Batteries.

The PCS can backup a subpanel that powers 5kW of loads, it can also handle 7.5kW of surge power for 10 seconds.

There are three modes: First is Backup Mode – Priority of the system is to keep the battery as full so that when you lose the grid, you will have maximum energy. Second is Self-consumption Mode – Priority of the system is to limit grid-usage, solar power is used to charge the batteries and power loads. When there’s not enough solar, batteries are used to power loads. Third is Advanced Mode – Off-peak hours and Peak hours are scheduled, during off-peak hours batteries are charged, during peak hours batteries are used to power loads.

Yes with the EMA Mobile App.

APsystems does provide our own batteries, but we do work with other battery vendors. This is a compatibility list of batteries we are compatible with.

Yes, with APsystems DS3, DS3D Microinverters at the moment. This is possible by putting the AC output of the DS3 or DS3D microinverters onto the backup service panel. When the grid goes down, the PCS creates a microgrid that the microinverters will follow and keep solar power on.

Determine max charge power of the batteries. Then pick the lower number between the battery charge power or the PCS charge power (5kW), multiply that number by 1.25 for the DC-AC ratio, and that is your maximum allowable power you can use for Off-grid Solar. Typically with a ELS-5K with batteries that can do 100A DC of charge, you can put a 20A string as backup power.

You will connect the PCS to your home’s internet either via WiFi or Ethernet, make sure you have connectivity. It is possible to connect the PCS to the internet via a third-party Cellular Router.

Our solution is AC-coupled, it only needs to be connected to the Grid on the Main Service Panel.

One is energy resiliency, when the Grid goes down you have batteries to backup the circuits on your backup service panel. The second is energy savings: with the proper mode settings, you can configure your system to limit grid usage and use batteries instead.

There are two factors to consider when picking how many batteries you want. One is capacity; more batteries means more kWh, which will give you more time. To estimate your time, divide kWh of capacity by kW of power consumed. Another is how much off-grid solar you can charge, more batteries allows you to have more off-grid solar.

The PCS is outdoor rated, but it’s best to have a cover to make sure it is protected from the elements. Make sure to read the temperature ratings of all equipment, including the battery you’ve selected and the PCS. The PCS is -25°C-65°C, but double check the battery as well. The PCS is installed on the wall and must be done upright.

Check the clearances requirements on the datasheets, the most up-to-date numbers will be on there.

Yes, when the Grid is on, APstorage will work with any AC-coupled inverter. However, when the grid is down, those inverters will stay off. If you system has DS3s or DS3D, you can move some of the microinverters into the backup service panel so that they stay on during off-grid, we are looking to expand that offering.

No, you need to get a separate ECU-R to manage APsystems microinverters on the roof.

Yes, the PCS will not backfeed power to the main service panel when the grid goes down. The changeover is in the milliseconds range.

The ELS-5K comes with two 80A CTs for production monitoring and two 200A CTs for consumption monitoring.


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 microinverter 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.


The UID or serial number is located on the back or side of the device and is a 12 digit number starting with a ‘2’.

Step 1: Switch on the ECU

Step 2: Press the AP button on the ECU

Step 3: Scan the QR code below to download EMA manager if not already done

Step 4: Open EMA manager,click “Local Access” at the bottom right

Step 5: Link to the ECU WIFI with the ECU ID, input 88888888 to log into the ECU;

Note: If the ECU WIFI cannot be found, please try again. Remember to keep the ECU close to the router. The WIFI name is the same as the first UID on the back of the ECU

Step 6: Go back to EMA manager APP, then Click “Workspace” and click “ECU Network”

Step 7: Choose the available router WIFI to link by wireless

When the connection is successful, both lights on the ECU will be green.

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.

Try to position the ECU closer to the microinverters and 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.

No, the microinverters must be scanned using the EMA Manager APP or EMA 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 EMA Manager 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 performance. Try to position the ECU close to the microinverters and try to avoid obstacles or other electrical equipment.

Yes, you can have this function with the ECU-C gateway and configuring the ECU-C “Zero Export” function ( CT’s are needed). See our product manual and our installation and configuration guide here here.

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.

EMA Manager APP is highly recommended as the scanning feature will ensure accuracy and ease of installation; however, it can be done via the EMA as well if needed.

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.

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


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

The EMA APP is designed for  system owners and DIY users. It allows users to track real-time performance of the photovoltaic system, see the system output by day, month, year, calculate energy savings and environmental benefits. It also allows system commission and configuration.

Please send an email to APsystems customer support team, and provide the ECU-ID and inverter ID. Our technical support team will add the new inverter for you.


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 EMA Manager 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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