Harmonics, Power Quality, Solar PV & Heat Pumps

I am certainly no expert in this field, but in the past couple of weeks, I have had two instances where harmonics have caused serious damage and inconvenience to our customers.

Harmonics are disturbances that are put back into the grid by switched power supplies and inverters. As all solar PV, most heat pumps, and some car chargers rely on inverters and switched power supplies, they have a detrimental effect on the power supply, both behind and in front of the meter. Harmonics severely affect the stability of the sine wave, causing interference to sensitive electronic components and equipment. They reduce the life of electronic components by causing overheating and can even stop electronic clocks from keeping accurate time.

In the context of the electricity grid in the UK, harmonics refer to a specific type of electrical phenomenon that can have both positive and negative impacts on the reliability and quality of the power supply. Harmonics are essentially unwanted and additional frequencies or waveforms that occur alongside the fundamental frequency of the electricity supply, which in the UK is typically 50 Hz.

Editor’s Note

This past week, I had issues connecting a certain heat pump to the grid. The heat pump does not comply with the standards, and the distribution network operator (DNO) is refusing to allow it to be connected without reinforcement. The quoted price for the reinforcement is £134,500, which is completely unaffordable.

I am not sure if the DNO is being unreasonable or if the equipment from the major manufacturer is not fit for purpose. We are still working on it and will get it sorted.

The second instance is an inverter heat pump that was installed a few years ago and has worked seamlessly and extremely efficiently since the day it was installed. However, after the homeowner installed a solar PV system, the heat pump started playing up, tripping out, and switching itself off.

It took some time to determine the problem. The harmonics from the solar inverter caused the heat pump’s inverter to fail. I replaced the inverter last week, at considerable cost to the user, and it is now working seamlessly.

Harmonics can also interrupt communication between and within units. When I fixed the heat pump, I installed a TP-Link wireline connection to get the heat pump online. With the solar PV system switched on, the connection did not work, and the wireline connectors got uncomfortably hot within minutes. When I switched off the PV system, the connection worked perfectly.

I am concerned about this, and so is the DNO. I have spoken at length, and somewhat heatedly, to a policy engineer in the Energy Networks Association (ENA). I think we need to take this issue more seriously than we are. We cannot wait until people’s TVs start blowing up before we start doing something about it.

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