July 27, 2022

Helpful tips and tricks on installing CTs


CTs (Current Transformers) will allow you to not only see the production of the micro-inverters, but also the consumption of the household and the imported and exported energy from and to the grid. Our EMEA Technical Support Manager, Alexander Holland, has some great tips & tricks to share with you to ensure that the installation of the CTs will be a success.

Meet Alexander Holland

Having joined Enphase in March 2020 has been an absolute pleasure so far. It’s very exciting to work for such an innovative company in the renewable energy sector that puts the customer first and that focuses on making the highest quality products available on the market. With our Technical Support team we try to provide world-class technical support for our installers, day in day out and no matter the challenge!

How to install CTs

In this blog I would like to share a couple tips & tricks on how to efficiently install CTs:

  • Make sure that the CTs are labelled. This will prevent you to attach a certain CT to the wrong terminal on the Envoy, especially for three phase systems

  • The arrow on the CTs should be pointed towards the loads (so not towards the PV-modules for production CTs and not towards the grid for the consumption CTs)

  • The CT has 2 wires coloured in white and blue: blue (bottom) goes on the lower terminal on the Envoy and white goes on top


Installing CTs on a three-phase system (3P + N)

  • In 3P systems the CTs must be placed on the right phase to ensure correct measurements. The power supply terminal of the Envoy defines what becomes the L1, L2 and L3 of our system.

  • To perform the phase-to-phase measurements, make sure to switch on the entire installation

  • Measure the voltage difference between the live wire on the power supply terminal of the Envoy and the live wire on the main circuit breaker for the consumption or on the live wire of the IQ Relay for the production

  • The CT is installed on the right phase when you don’t measure any voltage difference (0V AC) between the measured phases

  • If you observe a measurement of 400 V AC between the phases this means that you are measuring between two different phases; hence this will cause wrong production/consumption measurements

  • Repeat this process for all phases to ensure that the CTs have been installed correctly


We hope these tips & tricks will help you in becoming an Enphase expert.