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.


How do I contact APsystems technical support?

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.

I need on-site support, when can you be here?

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.

I see this FAQ is for professional solar installers. Do you have an FAQ for Homeowners / System Owners and End Users?

Yes, please see our Homeowner / System Owner FAQ here

Does APsystems have an installer certification program?

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.

Does APsystems sell direct to installers?

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.

I am not a professional installer and self-installed my system and now I’m experiencing problems. What do I do?

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.


What does the acronym ‘UID’ mean?

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

Where do I find the UID (serial number) of my microinverter?

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.

The inspector is asking what type of DC connectors you use on your products?

APsystems uses the industry standard Multi-Contact (Staubli MC4 PV-ADBP4-S2&ADSP4-S2) MC4 connectors for all DC inputs.

Can I install the YC600 and QS1 on the same circuit?

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).

Do you sell a single input inverter, as my installation only has 13 solar panels and I don’t need a dual or a quad?

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.

How many solar modules can I connect to a microinverter?

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

Can I connect different sizes, cells, or types of solar modules using various orientations on the same microinverter?

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

I am sizing my system, do you have a module sizing / compatibility calculator?

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

Can I use larger solar modules if I don’t utilize all the ports on the microinverter?

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.

How many inverters can I connect to each branch circuit?

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

Is the microinverter producing power when a PV module is connected but the system is not yet connected to the grid?

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

May an APsystems microinverter be directly connected via a plug to a wall outlet

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

I noticed that your inverters have an LED status light, what are the different colors and flash sequences?

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

Is grounding (earthing) required when installing APsystems microinverters?

Yes, please install based on your local electrical regulation or AHJ.

Do APsystems microinverters have an internal galvanic insulation?

Yes, a galvanic transformer is embedded in each microinverter.

Do I need to configure APsystems’ inverters to start working?

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.

Can I use a 400W+ module on a YC600 without damaging the microinverter?

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.

What is the peak, CEC weighted and nominal MPPT efficiency of your microinverters?

To view specifications, visit our library.

What is the maximum AC W output of your inverters?

To view specifications, visit our library.

I see a star washer installed on the mounting bracket of my microinverter, what is that used for?

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.

Is DC protection required for your microinverters?

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.

Can I install APsystems’ microinverters in a coastal environment?

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.

Can the QS1 be used in single phase 120V or 220V?

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.

Do the APsystems microinverters have built-in reactive power control (power factor control) to avoid penalties with the utility company?

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

Does APsystems recommend surge protection for the PV array?

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.

I have an off-grid application, can I use your microinverters?

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

One of the inverters has a flashing red LED indicator light. What should I do?

You can troubleshoot the inverter using this troubleshooting document. If the issue cannot be resolved after following these steps, please contact APsystems technical support.


How do I change my installer-level account password or email address for the EMA?

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.

In the EMA, my customer’s system shows 289w on one panel and 281w on another, is there something wrong with the inverter?

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.

I see NC (No Communication) on one or more panels in the EMA.

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.

In the EMA or EMA App, I don’t see power production. Can you help?

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

My customer is complaining that power production reported on the EMA is different than their utility bill. What is the discrepancy?

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).

What do the EMA traffic lights represent?

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 behavior 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.

How often does the ECU/EMA collect data from the microinverters?

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.

How do I interpret the ‘Energy Metering’ data I see on the EMA when using the ECU-C?

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

How do I replace an ECU or Microinverter on the EMA?

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’.

The module type shown in the EMA is incorrect. How do I fix the module type for my installation?

See our EMA User guide in our library here.

I have 300W modules on my roof, but I have never seen the module ever produce 300W, is there an issue with my installation?

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

How do I add a new installation to my installed base?

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.


What is the UID of my ECU-R, ECU-C, ECU-3, ECU-Z?

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’.

I see that you have two different communcation types; PLC and Zigbee, which ECU should I use with which product?

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

My customer recently changed their router or internet provider, how do I reconnect their ECU-R or ECU-C to the internet?

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.

What is the frequency of your Zigbee communication?

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

I have set-up and powered on the ECU and there is no communication between the ECU and the microinverters. Why?

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.

How do I install an ECU-R?

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.

How do I install an ECU-C?

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

Will the microinverters be automatically detected by the ECU after connection?

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.

I have connected the ECU with an ethernet cable, yet I don’t seem to be connected to the internet?

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]

I have YC500s and want to add YC600 / QS1s to my site, will my original ECU talk with all of your inverters?

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.

How many solar modules can an ECU reliably communicate with and demonstrate power production?

The ECU can communicate with 100 inverters. Larger sites may require additional ECUs for solid communication.

Maximum number of microinverters per ECU may vary depending on the PV array size and layout, maximum distance between ECU and microinverters in the array, obstacles (e.g. thick concrete walls and metal rooftops).

I have a site where the utility will not allow excess power back onto the grid. Do you have a function in the ECU to prevent power reinjection/export?

ECU-C features, such as the “Zero Export” function, can only be used on three phase systems in North America. See our product manual and our installation and configuration guide here.

How do I set-up the Zero Export feature with the ECU-C?

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

I see black lines on the ECU LCD screen, how do I resolve the issue?

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.

I have an ECU and I see -W or -Web on the screen, what does that mean?

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.

What is the difference between ECU-R and ECU-C?

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

How do I install an ECU-3?

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

I have replaced a defective microinverter, do I need to use ECU-APP to enter the new micro in the ECU?

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.

Can we use Zigbee antenna extensions?

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.

Can I use any CTs with an ECU-C?

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

The location of the main panel and the solar sub panel is longer than the CT leads. How can I extend the CT leads that go to the ECU-C?

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.

Can I access an ECU-R in the local area network?

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

How far from the microinverters can the ECU-R or ECU-C be placed? How far from the site’s wireless router?

Both ECUs can communicate with the inverters via Zigbee up to 76 meters (250 ft) with direct sight and can utilize Wi-Fi (WLAN) to connect to the site owner’s wireless router up to 9 meters (30 ft) with direct sight, however this last point depends primarily on the site owner’s wireless router’s capability.


I can not find the Array APP online, can you help?

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

The Home screen page on the ECU APP shows 0/22 (0/X) in the upper right-hand part of the grid, what does that mean?

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)

I noticed that you have two different APPs in the APP store; the ECU APP and the EMA APP, what is the difference?

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.


I want to add energy storage and back-up to a system, what do you have for options / how do I proceed / what do you recommend?

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.

I want to use a generator to ‘trick’ the inverters into thinking that there is a grid during a power outage, how do I set it up / is that okay?

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.

How do I responsibly dispose of a faulty inverter or ECU?

Contact your local electronic waste treatment facility.

Please provide the one line drawing for my installation, as the city is asking for plans?

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

There is no internet at the site, can the system owner still monitor their power production?

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.

Some string inverters have an outlet on the side of their inverter for use during a power outage, does APsystems have that too?

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

Can you tell me which solar PV design and simulation software(s) APsystems microinverters are available in?

APsystems is featured in many of the popular PV simulation programs today including; HelioScope, PVsyst, PVSol, Archelios, SAM and PVWatts

Does APsystems have an open API that I can use to program data on my own website/program?

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

I have a large wind turbine project and want to use your microinverter, is that possible?

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

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