Power Control: Zero Export System
With net metering being discontinued in many states in India and around the globe, zero export becomes the need of the hour. TrackSo with its Power Control Device, dynamically controls the power output of the solar inverters & allows zero* export of energy to the electrical grid.
– Avoid huge loss of power production due to delay in net metering
– Real-time power control of multiple inverters at a time
– Suitable for mixed PV systems with different inverter brands
– Universal Solution for all Inverter Brands
– Monitoring & Controlling via same device
Features of Power Control Device:
Smart Control: The device will ensure that the inverter ramps down the solar production smartly, by continuously analyzing the grid meter reading.
Ensure Zero Protection: Unlike reverse relay protection, our device ensures that the inverter doesn’t trip and minimum or no reverse feed-in is sent back to the grid.
Graphical Illustration: At any time client can log in to its device locally or via web interface and see the graphical illustration of power control working.
Remote Monitoring: TrackSo PCD can simultaneously acts as a Data Logger and send data on TrackSo Solar Remote Monitoring platform.
Logic
Zero Export works on a simple logic as mentioned below:
1. Read Active Power from net meter
2. Is Active power > Max Set point? If yes, increase power on inverters
3. Is Active power < Min Set point? If yes, decrease power on inverters
4. Repeat from step 1
NOTE:
Minimum set point: it is the minimum required power input from the grid supply
Maximum set point: it is the maximum required power input from the grid supply in case there is enough solar power being produced to cater the load.
Following is a simple SLD to showcase how Zero Export works in a solar PV system. To be able to do the zero export, we need a net meter [bi directional meter] on the incoming side. This meter should be MODBUS RTU enabled so that our Power Control device can communicate with it to read the ACTIVE POWER values.
Compatible Brands
Compatible with a wide range of inverters allowing Active Power Control via Modbus RS485 or Modbus TCP/IP. Following are few of the compatible brands.
Some Frequently Asked Questions
Can we monitor the system with this solution ?
Yes, the same device controls the setup as well as monitor the devices on TrackSo Solar IoT Platform.
Can it control and monitor 2 different Inverter brands on same device
Yes. It can even monitor 2 different inverters on 2 different protocols (Modbus RTU and Modbus TCP/IP)
Which dongles brands/model are compatible with WM-Mega and WM-Mini ?
You can use any dongle which can function in mode-switch mode. Example Huawei E3372 for 4G network, Huawei E3531 for 2G (edge)/3G Network
My inverter brand doesn't allow power control on modbus. Can this work ?
No. If your inverter doesn’t allow power control over Modbus this solution will not work.
Meter to be installed on Grid Side is 200m away from Inverter. How to connect?
Communication between the inverter and meter can be realized in three different ways:
- a direct serial RS485 connection between the inverter and energy meter
- a direct Ethernet connection between the controller and energy meter (Modbus TCP enabled)
- through or an existing network infrastructure
What all parameters are controlled in Zero Export ?
Only Active Power Parameter of the inverter is controlled via Modbus commands.
Can this guarantee zero export over a day ?
Zero Export is not absolute. There is instantaneous power going into the grid for a few seconds when the load is changed drastically. But, overall, the system maintains the Zero Export condition under normal circumstances.
What is the frequency of power control ?
The default frequency of the device is 5 secs. The speed on power control also varies on the MODBUS communication speed of all inverters. Most of them respond or act within a few ms, so the power export happens in the same time range
Installing a Bi-Directional meter on Grid side is mandatory for Zero Export ?
Yes, this is mandatory. Compatible brands list is available in overview document above and also here
Why is Bi-directional meter is required on Grid Side
It helps in identifying any export to the utility grid, and import from the utility grid as per which inverter generation is then controlled to avoid export of energy.
Does unbalance load affects working of Zero Export ?
Inverters can only produce equal power on all the 3 phases and due to this restriction from inverter for maximum solar output balance load should be present.
Controller provides following operating modes
Option 1: Average power for all phases: This assumes the load is balance and accordingly set Power output of inverter.
Option-2: Minimum power on any one phase-In case of unbalanced load controller can assume minimum power of any one phase and assume same is being produced by other two phases by doing this it ensures there is no export happening on all the 3 phases, but this will also result in low production.