FAQs - Gateway

Do I need a system communication Gateway and an Internet connection?

Yes. Internet access should be provided for the Gateway to enable HiQ to supply firmware updates and to provide customer support functions.

Monitoring PV solar inverter system gateway powerline

How many inverters can be used with one Gateway?

The maximum number of inverters on each Gateway is 200, although local conditions might reduce that number.

How and where should I mount the Gateway?

The Gateway is rated for indoor installation only.  Do not expose it to rain, extreme temperatures, or excessive dust.  It must be mounted indoors.  A utility closet or similar location physically close to the inverter system is ideal. It must be electrically connected to one of the three phases that are connected to the inverter.  Note that in large utility closets it is often easy to end up on an unrelated AC circuit accidentally, in which case communications are unlikely to be successful.


Recommended for 480V TrueString:  Add a 277 Vac outlet at the earliest entry point in the building to provide the best power line communication (PLC) signal possible.  Ideally a 277 Vac outlet next to the breaker.


Recommended for 208V TrueString:  Add a 120 Vac outlet at the earliest entry point in the building to provide the best power line communication (PLC) signal possible.  Ideally a 120 Vac outlet next to the breaker.


Gateway should be protected by a 15A OCPD


A wired Ethernet network connection must be provided to the Gateway for proper data retrieval.


If outdoor placement is required, the Gateway must be housed in a weatherproof enclosure. Take care to ensure that the memory card is fully engaged, as the Gateway will not communicate properly without one.


Line diagram, OCPD, PV solar inverter, AC splice

What methods are available to communicate with TrueString inverters?

Beyond the usual monitoring portal information, data on system performance may be downloaded in three other ways:


  1. Using the cloud API - this is the easiest programmatic method. Details are contained in the document here.

  2. Using MODBUS TCP from an Ethernet connection to a system Gateway within the site firewall. Details are available here.

  3. Using an optional Aux Port on an individual inverter. This needs to be special-ordered, and can't be retrofitted. It uses RS485 to communicate using MODBUS RTU, and requires dedicated wiring. The first two methods are preferred. More details are available here.

How much data traffic does the HiQ system transfer?

A rough calculation for normal traffic can be made using the following:

  • 256 bytes per inverter per minute while generating (daylight hours).
  • 256 bytes per inverter per 10 minutes while not generating (night time hours).

Worst case is to assume longest summer day hours to calculate and give some extra padding to be sure you don’t hit any installation limits, such as might be imposed by cell modem plans for example.


Other possible data usage:

  • Firmware updates take about 1 megabyte of transfer. These are fairly rare.
  • Remote diagnostics uses data at an unpredictable amount as it depends on what is being done at the time. These occurrences are rare also.


An example calculation for a system with 20 inverters is as follows:

  • Assuming 14 hours daylight and 10 hours night time with 20 inverters
  • 20 inverters x 256 Bytes x 60 (intervals per hour) x 14 hours = 4,300,800 Bytes /day
  • 20 inverters x 256 Bytes x 6 (intervals per hour) x 10 hours = 307,200 Bytes /day
  • 4,300,800 + 307,200 = 4,608,000 Bytes (4.608MB) total  per day
  • Assuming a 30 day billing period, 4.608MB x 30 Days = 138.24MB per month in normal usage for 20 inverters.

How do I troubleshoot Gateway connectivity issues?

Recently added functionality on the Gateway gives greater insight during installation on possible issues. The 'Array Summary' screen has been updated with "indicator lights" showing the status of four critical elements. A green indicator means the following:


  • AC - The Gateway's AC wiring is correct. (Neutral is connected, voltage in within tolerance, no dangerous spikes present.)

  • SD - The SD card is inserted and the file system is OK.

  • NET - The network is connected.  This doesn't necessarily mean that it's able to communicate, but the cable is OK and the Gateway has acquired an IP address.

  • HIQ - The Gateway was able to contact the HiQ server and upload data.

The PLC signal strength is low - what do I do?

Occasionally PV installs using TrueString inverters experience issues with the Power Line Communication (PLC) used to communicate between the inverters and the HiQ communication gateway. One reason for this can be that the nearby grid is sufficiently low impedance that the PLC signal ‘leaks away’ and has insufficient strength remaining for proper communication to occur. In this instance the PLC Cores provide a means of increasing grid impedance in the frequency band used by the HiQ system to ensure sufficient signal remains. External noise can be another source of issues.


HiQ Solar offers third party PLC Core common mode chokes as an ordering convenience. More information can be found in the PLC Core Guide.

Where did my 'Discover' button go?

A recent Gateway firmware update made improvements to the discovery functionality. The 'Discover' button has been promoted to having a screen all to itself - from the 'Inverters' page, press 'Setup'. This brings up a page dedicated to the discovery, addition and deletion of inverter serial numbers from a site locally.


Also included is a default discovery search that does not delete previous entries, only adds new units it finds to the existing site list. For a clean-sheet search the 'Add Only' check-box can be unchecked.