Wattwatchers systems (like Fleet, Dashboard and MyEnergy app) expect CTs to be installed in a specific direction. If this is not done correctly, incorrect data will be stored for the device.
Incorrect data cannot be changed or deleted once it is recorded, so it is important to get this right at the time of installation.
Energy data is positive when the current is flowing in the same direction as the arrow etched on the CTs themselves.
Rephrased: the direction following the purpose/utility of the measured circuit should be positive.
Channel category and Notes on the directionality of the CT
Grid Connect
Positive for imports (drawing from the grid). Negative for exports (sending to the grid). If no generation source is specified for the site, this should always be positive.
Natural flow: provides energy from the grid into the site, so imports are positive.
Solar Generation
Positive when the solar system is producing power. Sometimes this can be a small negative value if the inverter is drawing power for operation from the grid or for overnight standby consumption, but as a general rule should always be positive.
Natural flow: the utility of a solar install is to generate power and energy, so it should always be positive.
Battery
A battery follows the same pattern as generation in that it will be positive when discharging power into the premises (generating energy), and negative when drawing power from the grid (i.e. charging).
Natural flow: the utility of a battery is to provide stored energy on-demand, so discharging is positive.
Hybrid Solar and Battery System
As per Battery, except a positive value may represent either solar generation or battery discharge. We are unable to tell the difference (i.e. between solar generation or battery) from energy flows alone, although the time of day can provide some hints — i.e. a positive generation value at 9 pm at night is highly unlikely to be the result of solar generation. Note also that we are unable to determine the consumption of the battery on solar generation, as this process occurs before measurement by our CTs occur.
Natural flow: the utility of a hybrid solar + battery is to provide power and energy, so generation is positive.
Battery Backup Circuit
This channel measures “high availability” circuits that are connected to the output of a battery energy storage system to provide backup power in the event of a grid outage. This includes appliances that should stay on as much as possible even during a grid outage, e.g. medical equipment, fridges, and critical circuits etc. Since this is a special category of loads, the same convention is applicable i.e. current flow should always be positive when the energy is consumed by the appliances.
EVs
Positive values represent EV charging (either from the grid or on-site generation sources). These should never be negative.
Natural flow: the utility of an EV is to drive it, and so charging it is the natural flow. So positive when charging.
All other categories (loads)
Positive values represent drawing power (either from the grid or on-site generation sources). These should never be negative.
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