The Tigo Energy Intelligence (EI) Residential Solution has a choice of operating modes, which can be managed within the app (once the battery has been installed and added to the system).
To access the battery controls, simply sign in to the Tigo App and go to the desired system.
Then:
- Press the Settings icon (bottom right)
- Select Energy/Battery Management (top)
Once you are on the Energy/Battery Management page, you have control over the 4 operating modes:
- Standby (non-selectable)
- Self Consumption
- Time of Use
- Backup
The first mode (Standby) is non-selectable state of readiness. The remaining 3 modes help to manage the battery behavior (depending on the homeowner’s preference).
Standby
Standby is a non-selectable mode. No matter which operating mode the EI Residential System is set to, it will enter Standby mode once the battery state of charge (SoC) reaches 10%. This means that the battery is no longer charging or discharging. The consequence of entering Standby mode is discussed for each of the operating modes listed (below).
Self Consumption
The primary objective of this mode is to self-consume as much of your own generated energy as possible, to reduce dependence upon the local utilities. The solar will power daytime loads and charge the battery, and when the sun goes down, the home will shift to battery power and supply the home throughout the night.
If the home can make it through the night on battery power, the inverter will begin to power loads and charge the battery when the sun comes up. A properly designed system can do this indefinitely. If the battery reaches its low state of charge during the nighttime hours and enters into standby mode, the system will automatically use grid power without interruption to power the loads until there is enough sun to power the home.
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The homeowner can set a discharge limit to a specific amount so that the battery capacity can be retained (in case the grid goes down). A reasonable setting for most systems is 20%. |
Here is an EI Portal representative example of a typical Tigo EI System operating in Self Consumption:
A. The batteries are the sole power provider for the home (blue line below 0W reference).
The state of charge continues to drop until around 7 a.m. (black line)
B. At 7 a.m., the PV inverter starts producing (green) and exceeds the usage within the house.
C. The solar starts to charge the batteries (blue line above 0W reference).
D. The entire solar output (green) is powering the loads (red) for most of the day.
E. The solar production stops around 7 p.m., and the battery starts discharging
(blue below 0W reference)
Battery charging
While in Self Consumption mode, the batteries are only charged using solar. If the batteries are depleted during nighttime hours, the system switches to grid power until the next day (when there is enough solar to charge the batteries).
Time of Use
This operating mode is typically used by homeowners whose local utilities have offered tiered rates (based on the time of day). During peak hours, generally, between 4 – 9 p.m., the utility charges a higher rate than during off-peak periods.
When the app is set to Time of Use, the system operates its self consumption based on a focused time schedule set by the user (typically during high peak rate times). The batteries can also be set to charge during a separate window, typically when the rates are lower (i.e., 10 p.m. to 2 a.m.)
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Time of Use By default, the ToU mode allows battery charging only from solar.
AC Charging Select to allow the utility power to assist with battery charging during nighttime hours when no sun is available.
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⚠️ CAUTION! You must check with your utility company before selecting AC Charging. Especially, if you are in an area where battery sell-back (to the grid) is allowed. Typically, these interconnection agreements only allow battery export if the battery is filled with “green electrons” captured from renewable energy (ie., solar). Charging the battery using the grid and then discharging it to the grid can result in backlash from the local utilities. If you are in this type of utility agreement, then you should ensure that AC Charging is de-selected.
In this example, the ToU window is set to 7:00 – 9:00 p.m. This is the only time during the day when the batteries will discharge. The system is set to use only solar energy to charge the batteries.
A. Batteries charged (blue) using available solar
B. Solar production (green) supplies energy for the daytime loads (red)
C. The 7:00 to 9:00 p.m. window, the batteries have been set to discharge
Backup
The significant difference between this mode and the previous two is how the system behaves when the grid is up. Self Consumption and Time of Use are grid interactive modes, meaning they operate when the grid is up. If set to Backup mode, the system will only discharge the battery when the grid is down during a power outage.
There is more risk of abnormal behavior for the Backup operating mode if the system has not been correctly designed or if the outage extends past a few days with inclement weather. Bad weather usually means low sun availability, leaving the system without a power source to charge the battery.
Unlike the previous two modes, once the battery has reached a low state of charge and enters Standby, there is no grid support to keep the lights on. A generator can help hedge system availability as long there is enough fuel to last through the outage.
When the grid is up, the Backup mode graph may or may not show battery activity. The primary behavior exhibited is PV production (green) and the consumption of the home (red). The state of charge will remain near 100%, and the system is just waiting for the grid to go out.
Notice that although the system is in Backup, at about 2 a.m., the batteries were charged (blue), and the State of Charge line (black) went back up to 100%. This is expected behavior.
Maintaining a full charge on Lithium-ion batteries can degrade their life span. The TIgo EI battery management system constantly monitors the battery bank's state of health and allows the batteries to discharge a small amount to keep them healthy.
While some energy storage manufacturers hide these small State of Charge deviations, we proudly display them to let you know the system is appropriately managing battery health.
| Once the EI system detects a grid outage, it immediately switches to Backup mode and starts powering the home, regardless of which mode the system is in. The EI system will always switch to Backup upon detecting a grid outage! Once in backup mode, the graph will look similar to the self-consumption example. |
Many people who start out in Backup mode quickly learn that they can get more from their energy storage investment by switching to either Self Consumption or Time of Use mode. This way, the system can offset their utility bill when the grid is up but still have battery capacity for a grid outage. Generally, they start with Time of Use and open the time windows wider than previously explained, for example, noon to 9 p.m.
The good news is that you cannot damage the system by experimenting with the other operating modes. You paid for it, so use it! If you know bad weather is on the way, you can manually set the operating mode to Backup so that you will have a full battery if an outage occurs.
If you have any questions, please contact the Tigo Sales Engineering team.