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WVC Modem and the KDM Monitoring System for WVC Micro Inverters

This is my review of the WVC Modem and KDM Monitoring System for WVC Micro Inverters manufactured by Dongguan KaiDeng (KaiDeng Energy Technology).

Please note that the WVC Modem does not support the 2018 Version of WVC Micro Inverters.
For the 2018 Version of the WVC Micro Inverters use a “WVC WiFi (Wireless) Modem” which is very different to the “WVC Modem” and not reviewed here.

The KDM Monitoring System consists of a Modem that uses 433MHz RF to communicate with the WVC Micro Inverters and some rather rudimentary Software called [obviously] KDM System.

I purchased the WVC Modem (as it’s called) at the same time I purchased a bunch of WVC-600 Micro Inverters (which I reviewed separately here:

What you get in the Box:
You get the WVC Modem, Antenna and KDM System Software. Depending on the “bundle” purchased, the supplied accessories will vary (Serial Cable and/or extended Antenna).
The basic WVC Modem has a Serial Port to connect to a PC – the one I purchased came with a Serial to USB Cable so keep this in mind when purchasing as they are sometimes sold separately.
Also, the one I purchased came with a free-standing Antenna with a 2.5M cable which proved to be invaluable soon after installation.

Installing the KDM Software is pretty straight forward.

You only need to configure two things; 1) the Serial COM Port that your PC recognises the Serial Cable on and 2) enter the 4-digit Hex Numbers of each Inverter (IE: 85F2).
Remember to make note of these numbers when installing the Inverters and their locations and/or the panels they are connected to (I had to remove a couple of panels to get to the Inverters because I forgot to record their numbers – don’t make the same mistake).

This is NOT a WiFi (Wireless) Modem so don’t expect miracles – the Modem simply receives broadcasted RF Data from each Inverter so the Inverter’s Status can be monitored on a PC.

The WVC Modem does NOT “buffer” Data (store historic Data) – meaning that, if the KDM App is closed (or the Computer goes to sleep or is turned off), no output from the Inverters are recorded which impacts the overall recorded power generated.

If you want to send Data to the Cloud then you need to get the 2018> version of the WVC Inverters and their supported WiFi (Wireless) Modem then setup a Cloud Account on the KDM Website.

My Review
The KDM System (Modem and Software) is very basic and sufficient to monitor the health/status of the WVC Inverters. You pretty much get what you pay for (which is not a lot).

For me, I am OK with the KDM System as it does a good job at real-time monitoring of the Inverter’s output. I haven’t yet had an Inverter failure but, if an Inverter failed, it would be pretty easy to identify it.
Recording of historic data is a bit of hit-and-miss and explained here:

At least once a day I notice that one or more (random) Inverters don’t show a satisfactory output.
If I close the KDM Software then re-open it (close it completely, don’t minimise) then the Outputs show a satisfactory level.

If left unnoticed for long periods of time, the total output recorded is way under-reported.

Just as I am writing this review I again noticed a measly 20 watts coming from two Inverters that should have been producing 300W+ each - I closed the app then re-opened it – suddenly the output of the recorded Inverter jumped to 323W!

Sometimes when this happens, closing then re-opening the App doesn’t work – only power-cycling the WVC Modem sorts it out. This is not an output fault of the actual Inverters but a “monitoring” issue. If left unnoticed for long periods of time, the average output for the recorded periods becomes totally inaccurate.

So, without constantly checking multiple times a day that the App is doing what it’s meant to do, you will NEVER get a full and accurate recorded output.

The signal strength of the RF between Inverts and Modem is pretty good – I had a bit of an issue at first due to the distance between my Inverters and the Modem which was worsened by the tin roof on the house. This resulted in some of the Inverters showing as failed because the Modem could not connect to the Inverters – fiddling around with the antenna position resolved the issue.

I use the WVC-600 Inverters which have two panel inputs. Other Inverters like the WVC-1200 have four inputs for four panels.
The KDM Software can’t monitor individual Panels (individual inputs on each Inverter) – only the collective output of each Inverter. If one panel is disconnected (or fails), the overall output of the Inverter drops and there is no way (using the Software) to identify which of the two panels it is (or whether the actual Inverter input is at fault).

In summary, the KDM System is a good (but rudimentary) tool for inspecting the health of your solar array and identifying the proximity of the failure up to the number of panels connecting to each Inverter. The average output recorded (not generated) of your array can be severely affected when the Modem/Software gets a little confused (which is quite often).
I did have a play with setting up a Cloud Account on the KDM Website to see what the new generation of KDM WiFi (Wireless) Modems could do. I was really disappointed in the English translation of the Website and difficulty of use – but the new generation seems to be in its infancy and I may revisit and upgrade the WVC Inverters in future to play with.