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.

The UID or serial number is located on the front of the device and is a 12 digit number starting with a 1, 4, 5 or 8.

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

Yes, you can mix and match the YC600 and QS1 on the same branch circuit as they share a common AC connector on the inverter and AC connection on the AC trunk line, up to 14 PV modules, or up to the 16A breaker threshold (U.S. region).

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.

Good question with multiple answers:
YC600 – designed for up to two solar modules
QS1 and YC1000 – designed for up to four solar modules

Yes, as the YC600 and QS1 both have independent MPPT allowing for different sizes, cells or types

No, the YC1000-3 is a single MPPT and does require SAME solar modules in the SAME orientation

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

APsystems micros work well with most of 60 or 72 cells PV modules. APsystems is agnostic to the brand of PV panel you choose. YC600 and QS1 inverters output 300W per channel. This does not mean pairing them with a 300W PV module. You will always want to oversize the PV module since the rated STC listing is under optimal conditions and you often won’t have that due to weather, shading, clouds, leaves, dust, etc., not to mention the wear and tear over 25 years that will degrade your panel quality. Most professional installers use a sizing ratio of 1.2 or 1.25 to determine the ideal panel sizing for your inverter. That would mean a PV module of 360W to 375W for pairing with the YC600 and QS1. Higher capacity PV modules will not damage or negatively effect the inverter. You will simply have increased clipping. Be sure to also check the PTC listing of the PV module for a more accurate expectation of power output.

As the YC1000 has only 1 MPPT, PV modules can be oversized up to 400W if only 3 channels are used.

YC600: 7 inverters
QS1: 3 inverters
QS1A (LATAM only): 3 inverters
YC1000-3-208: 3 inverters
YC1000-3-EU (230/400V): 12 inverters
YC1000-3-480: 8 inverters

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

Yes, 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.

Oversizing the module cannot damage the inverter as long as the input voltage and current of the module are within the inverter specification. To view specifications, visit our library.

To view specifications, visit our library.

To view specifications, visit our library.

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.

DC Arc-Fault Circuit Protection only applies to systems with DC voltages above 60Vdc (EMEA) or 80Vdc (US and Canada). APsystems microinverters are inherently exempt from this requirement as they always operate well below 80 Vdc.

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.

Yes, APsystems has specific product to meet the demands of many different grid configurations, please refer to the APsystems website for availability in your region.

The QS1 and YC600 are compliant with local regulations regarding RPC, including California Rule 21, EN50549, and VDE AR-N 4105.

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.


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: Make sure the ECU is connected to the internet. Make sure that ECU’s (ECU-R or ECU-C) antenna are not in the AC box. Try repositioning the ECU antennas (ECU-R or ECU-C) or use an antenna extension to be closer to the micros, reposition the ECU closer to the microinverters for better communication. In the case of an ECU-3 device or earlier with PLC communication (YC500 inverters), make sure you have not recently added some other devices (i.e. AC-connected devices) which can create distortion of the PLC signal and prevent proper communication between the ECU and the inverters. If so, you can try to plug in the ECU’s AC power plug (PLC) as close as possible to the PV array. You can also try using an ethernet cable to connect to the router instead of Wi-Fi. If it shows NC for more than 2 days, contact your local technical 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.

See the ECU & Inverter compatibility guide in our library for more information

The ECU-R 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 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]

No, the YC500 utilized PLC (Power Line Communication) while the YC600 and QS1 utilize Zigbee, a completely different protocol. You would need two different ECUs and different cabling/accessories but the data can be merged on the EMA easily.

The ECU can communicate with approximately 400 solar modules, so ~200 YC600s and ~100 QS1s. Larger sites may require additional ECUs for solid communication.

Yes, you can only 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.

The ECU-R is a basic monitoring gateway, while the ECU-C has advanced functions; metering function, zero export and redundant energy control.

For the ECU-3 only, follow the guidelines per the ECU-3 training document here. For more information, visit our library.

The ECU-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.

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


The Array APP has been discontinued, to map your systems please login to your EMA account.

The scenario means that the ECU cannot communicate with the inverters, check:
• Verify that the inverters are compatible with that ECU (Zigbee, not PLC)
• The correct inverter serial numbers have been entered
• The Zigbee antenna is / was properly connected to the ECU and not shielded by any substantial obstacle
• Verify that the distance between the ECU and the inverters does not exceed 50m (165f)

The ECU APP is a tool for installers to use in the initial set up of your system. The EMA APP is the monitoring tool system owners will use to monitor their energy production on their smart phone.


APsystems inverters are agnostic and will function perfectly with all AC coupled storage solutions on the market today. We do not recommend a specific brand or model, as this is a professional choice for the features and function.

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-R 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, Archelios, SAM and PVWatts

The API is only available for certain installers. The API calls currently available include five system level calls. Access to the API will require a unique user name and password provided by APsystems on a case-by-case basis and a yearly paid subscription is required. 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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