Fronius is a very popular brand when it comes to inverters, however, on this occasion, we will focus on one of the essential components of the PV system, the energy meter.
Why Do I Need Fronius Smart Meter?
Fronius offers the Smart Meter to transmit technical information regarding the connection to the grid and the Fronius inverter.
This product is a bidirectional meter that measures self-consumption (including the household load curve) and also the production from the PV system within an accuracy of 2%.
The communication is done via the Modbus RTU interface (Modbus communication protocol that conforms to the SunSpec Alliance standard) specially developed to be synchronised with Fronius inverters.
The device is connected to the built-in data logger that can be found in the down-side of the inverter and will allow you to visualise the PV system performance on the Solar Web monitoring system from Fronius.
Among other things, the Solar Web portal allows you to check daily energy balances with load curves and instantaneous power balances within the PV system.
You can also take a look at your earnings in AUD and check on the avoided CO2 emissions.
Also, if you have chosen an energy storage solution for your installation with the Fronius Symo Hybrid inverter, you can also visualise the energy stored in the battery and how this stored energy was used later on.
All of these features allow you to monitor your consumption times and integrate energy management to change your patterns of consumption if needed, to achieve bigger savings
The energy meter measures voltage, frequency, current, reactive and apparent power, energy and running hours within a 2% accuracy.
As an energy meter, it lets you control the amount of energy that is sold back to the grid and establishes the energy limits if necessary.
There are two main options for the Smart Meter: the 50 kA-3 version and the 63A version which is also divided into two possibilities (the split-phase and the three-phase).
The 50 kA-3 is a three-phase energy meter that can be connected to a grid of nominal 400V.
The model tolerates a maximum surge current of 50 kA per phase and consumes less than 3 W.
As you can imagine this meter is generally used for commercial applications.
The meter can be used with external transducers (current transformers for measurement) which is why it’s ideal for electrical installations where grid connections cannot be modified.
Despite the fact that the 50kA model is designed mainly for three-phase installations, it can also be used for single or dual phase installations.
It is important to note that this Smart Meter model cannot be synchronised with the Fronius Data Manager Version 1; it can only be synchronised with the Fronius Data Manager Version 2.
As a general overview, the following diagram illustrates the PV system integrated with the Fronius Smart Meter and the connection to the grid.
The installation procedure is very simple as you can see from these steps:
- Mount the Smart Meter on the rail within your switchboard
- Turn on the communication between the Data Manager Version 2 and the Smart Meter
- Place the current transformers on each phase of the grid to measure current values.
- Make the connections for voltage measurement along with the fuses.
- Activate the Smart Meter to transmit information to the Data Manager Interface.
- Check that you are able to see the parameters of the installation on your Solar Web account.
A schematic of the electrical installation for the Smart Meter can be seen in here:
The RS 485 represents the terminal output with the ModBus RTU protocol that must be connected to the Fronius Data Manager via a CAT 5 Ethernet cable.
It is also mandatory to terminate the bus line with an external 120 Ω resistor in order to ensure proper bidirectional communication between the Data Manager and the Smart Meter. This resistor is included in the Smart Meter.
It is also important to note that the current transducers are not included with the Smart Meter and they need to be purchased separately when you know if the permitted secondary side of the transformer is 1A or 5A.
On the other hand, the other models are the 63 A -1 and 63 A-3 Smart Meters, one strictly for single phase applications and the other one for three-phase applications.
Connections and grid voltages are the same as the 50 kA version, but an important difference is a current limit, which in this model is 63 A per phase, the reason why it is the Smart Meter for most residential applications.
We have taken a look at the bidirectional Fronius Smart Meter for connection to the grid.
This Energy Meter connects with the Fronius inverter to provide information on daily energy balances within the PV system including consumption, energy storage and PV energy produced.
Steps are easy and can be installed on any electrical installation since the current measurement is done via external current transducers that can be added without any modification to the grid connection.
Truly a very nice choice to monitor the performance of your PV system!
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Photo credit: Fronius