Application Note: I3O2 Module & External Grid Charge
One of the applications of the I3O2 module is to use it in conjunction with a contactor to control when the power supplied to the load is coming from the grid and when it is coming from the solar and battery bank. This will turn your inverter into a "smart" inverter that will be able to switch on and off the grid power supply based on what actions you set. The contactor will act as a switch that is used to turn on and off the power supplied from the grid. The I3O2 module will be the relay that communicates to the Wattmon master module and decides when to switch on and off the contactor.
You will be able to set up a set of actions that will turn on the switch, turning on the power supply from the grid, when your battery bank goes below a set percentage. This will typically happen on a cloudy day when there is not enough sunlight to generate an adequate power supply for the load. When there is enough power being generated by the solar and the battery bank is above the set percentage, the switch will be turned off, and the solar and batteries will supply the power for the load. This will allow any solar power being generated to not be wasted; if the grid is supplying power for the load and the battery bank is full, the power generated from the solar will not have any use. Turning off the power supply from the grid will prevent this from happening and allowing the solar to be used to power the load instead of being wasted. These actions will also benefit the batteries' health because whenever the batteries go below 70%, or whatever value is set, no more power will be consumed from the batteries and the power for the load will be supplied from the grid. Discharging batteries below 70-80% can be harmful to the lifespan and overall health of them; that is why it is beneficial to have the load supplied with power from the grid when this happens so that the batteries can recharge. The basic set up of this example is shown below in Figure 1, and the following note will explain in detail how to set this up.
Fig. 1: Basic Setup
Scan for I3O2 Module
If the I3O2 module has not already been plugged in and configured, plug the I3O2 module into the master module's device port, or into any of the ports on a module that is attached to the master module. Go to the Control Panel > Devices > Add > Quick Scan Wired Bus for New Devices. Once the scan is complete, the I3O2 module should appear in the Device List as it does in Figure 2.
Fig. 2: Device List
I3O2 Module & Contactor Set Up
To have the I3O2 module control when the power supply from the grid will be switched on and off, the I3O2 will need to be connected to a contactor. To set up the contactor, turn off the main breaker. Connect the 220V power supply from the grid to the L1 terminal of the contactor. Connect a thin gauge wire from the L1 terminal to either of the OUT1 pins. Connect a second thin gauge wire from the other OUT1 pin to the A1 terminal. Connect a third thin gauge wire from the A2 terminal to the neutral terminal of the input side (labelled as NO13 in Figure 2 below). Connect the output side of the contactor to the inverter; connect one wire (will be the live wire) from the T1 terminal and the other from the NO14 terminal (will be the neutral wire). Refer to Figure 2 for clarification. When the relay is switched on, the contactor will switch on. The power from the grid will then be able to travel through the contactor to the inverter. When the relay is switched off, the contactor will be switched off and there will be no flow through the contactor.
Fig. 2: I3O2 Module & Contactor
Configure Device & Actions
To set up the I3O2 module online, go back to the Devices page and click on the "Action" button that corresponds with I3O2 module being used and then "Configure" from the drop down tab. In the Configure Roles section, you will need to assign a role for Output 1. From the drop down tab for Output 1, choose Relay for Main Inverter Input as is shown in Figure 3. Click the blue "Apply Changes" button near the top right.
Fig. 3: Configure Device
Next, the actions will need to be added that will control when the contactor is switched on and off. Go to Control Panel > Actions > Add Action. The first action will be to switch on the contactor so that power will be supplied from the grid. To do so, in the Action Trigger Condition(s) section specify Value Type as System Variable, Value 1 as Battery Percent, Comparison as Is Less Than, Value 2 as Fixed Value, and Value 2 Type as 70. In the Actions to Execute section, specify the Action as Switch On and the Variable as Relay for Main Inverter Input. Click "Apply Changes." Refer to Figure 4. This action will tell the contactor to switch on the power supply from the grid when the battery percentage is less than 70% (or whatever percentage you specify).
Fig. 4: Configure Action - Switch on Relay
The second action will be for switching off the contactor which will turn off the power supply from the grid. To do so, in the Action Trigger Condition(s) section specify Value Type as System Variable, Value 1 as Battery Percent, Comparison as Is Equal To, Value 2 as Fixed Value, and Value 2 Type as 100. In the Actions to Execute section, specify the Action as Switch Off and the Variable as Relay for Main Inverter Input. Click "Apply Changes." Refer to Figure 5.
Fig. 5: Configure Action - Switch off Relay
Now you should have the I3O2 module and contactor set up properly so that the grid power supply will be switched on when the battery percentage goes below 70% and turned off when the battery percentage reaches 100%.