In this article:
- Overview
- Can the CT cable be extended? Is there a maximum length?
- Will the signal from the CTs get distorted if I put them close to other CTs?
- Do I have to have a CT fitted to the solar PV feed or not?
- Is it better to connect the PV or AC Battery to the spare CT input?
- Why does my harvi stop transmitting when it’s dark?
- Are hardwired CTs more accurate / updated more often than a CT on a harvi?
Overview
harvi is a clever little device that allows the zappi and eddi to be installed without wiring a direct CT clamp.
The harvi is an energy-harvesting wireless sensor – an essential part of the installation process that saves time and money.
It eliminates unsightly wiring, prevents disruption to your home decor, and enables the myenergi product family to be installed without using a hardwired current transformer.
Can the CT cable be extended? Is there a maximum length?
Yes! You can extend them up to a maximum of 100m but you MUST use a twisted pair cable (cat5). This is to maintain correct polarity throughout. Up to four CT cables can be extended using the separate twisted pairs in a CAT5 Ethernet cable.
Will the signal from the CTs get distorted if I put them close to other CTs?
No! The CTs can be placed close to other CTs where required
Do I have to have a CT fitted to the solar PV feed or not?
Providing the ‘Grid’ CT is fitted then zappi/eddi/libbi will work perfectly. The solar PV CT isn’t compulsory but it will provide solar PV information on the zappi/eddi/libbi screen. This will also show on the app.
Is it better to connect the PV or AC Battery to the spare CT input?
The PV CT is used only for monitoring purposes. Adding an AC battery CT allows you to avoid battery drain and give the battery priority over any surplus generation (in the ECO and ECO+ modes Using a 3rd party battery with Myenergi devices). If you don’t want your stored energy used for heating or EV charging it is advisable to connect the CT to monitor an AC battery.
If the harvi is only monitoring the PV it will stop transmitting at night and a red “harvi” light will show on the hub. Depending on the placement of the hub, this could be irritating to some.
Why does my harvi stop transmitting when it’s dark?
harvi ‘harvests energy from the circuit it is measuring so it doesn’t require a battery. As a result, it will stop transmitting if there is no power flowing in the measured circuit (eg at night if measuring PV generation).
If you have a spare grid clamp you could use this to keep harvi awake by connecting it to a spare CT input and then clamping the CT around a cable that always has power flowing through it. Remember to set the CT Type to None if you do this.
Are hardwired CTs more accurate / updated more often than a CT on a harvi?
The simple answer – yes! As harvi harvests power, it transmits more when there is a high current flowing through the CT. At low power flows a hardwired CT will give a more accurate reading
Thank you for choosing myenergi as your trusted energy partner. We look forward to continuing to innovate and serve you better in the future!