DESCRIPTION: Recommendations for installing TBB RIO SUN II inverters in environments isolated from the electrical grid (Off-Grid)
INTRODUCTION
One of the main advantages and key features of the TBB RIO SUN II inverter series is their ability to operate in environments isolated from the electrical grid, such as farms, country or retreat houses, or any location without grid access.
In these types of installations, since there is no support from the electrical grid, oversizing the installation is essential. In other words, you must consider that the only available energy source is solar (which is intermittent and not continuous), so calculating the number of solar panels and batteries is fundamental. It is also possible to include an external energy source, typically a generator.
All of this can be seen in this FAQ
REQUIRED CALCULATIONS
As mentioned earlier, since there is no grid support, it is necessary to oversize the installation. There are 3 steps to follow in the sizing process.
STEP 1: ESTIMATED CONSUMPTION.
This involves accounting for all devices that consume electricity in the installation and making an (overestimated) calculation of the hours of consumption for each. The goal is to obtain the total daily consumption to know the battery capacity needed. Example:
| DEVICES | UNITS | POWER (W) | Usage Time (h) | Daily Consumption (Wh/day) |
| Refrigerator | 1 | 120 | 24 | 2880 |
| Microwave | 1 | 800 | 0.5 | 400 |
| Oven | 1 | 1000 | 0.5 | 500 |
| Washing Machine | 1 | 500 | 2 | 1000 |
| Lights | 4 | 20 | 8 | 640 |
| TV | 1 | 100 | 4 | 400 |
| TOTAL | 2540 | 5820 |
STEP 2: BATTERY CAPACITY.
After calculating the daily consumption, you must determine the actual required battery capacity. This is not the same as daily consumption, since you must consider the days of autonomy, depth of discharge, and loss factor. The following image defines these parameters and the formula to obtain the real battery capacity.
In our example, the battery capacity is calculated as:
Battery capacity (Wh)= (5820Wh*2)/(0.95*0.98)=12502.69 Wh
Within the VISIOTECH catalog, it is recommended in this case to use the DY-POWERBRICK-14336
STEP 3: SOLAR PANEL CALCULATION.
Once the installation has been sized in terms of batteries, it is necessary to calculate the required solar panels. This is not only based on the power of the devices present in the installation, but also with the goal of being able to fully charge the batteries, taking into account, as mentioned earlier, the discontinuity of the resource, in this case, solar energy. This is the formula to obtain the required power in solar panels:
Where the safety factor is 0.8 and HSP is the peak sun hours, a method used to determine the amount of solar energy a photovoltaic system can generate in a specific location. It is based on the amount of solar radiation that hits a surface over a specific period, usually a month. You should choose the lowest HSP for a month of the year. In our example, we use the province of Madrid and get the following:
Panel power (W)= (5820Wh)/(0.8*2.377)=3060.58 W
The number of solar panels, therefore, will be the division between the required power and the power of the panel chosen by the customer. So, if a 500W solar panel is chosen, the number of panels will be 3060.58/500 = 6.12 panels, that is, 7 solar panels.
STEP 4: REQUIRED INVERTER CALCULATION
In this case, it is quite simple. Since 3060W of production is needed, a 3KVA inverter can be used. In this case, TBB-RIOSUN2-3KVA-S.
CONNECTION AND PARAMETERIZATION
It is recommended to read the following FAQs, which detail the necessary connections and parameterizations for a TBB inverter and a DYNESS battery installation, as well as how to create an installation and monitor it in the cloud.
INSTALLATION AND PARAMETERIZATION OF A GENERATOR
Installing a generator in an off-grid installation is highly recommended for the reasons described above. The intermittency of solar energy, battery errors or failures... can cause the installation to be left without supply. Therefore, having a backup energy source is very useful.
The most typical off-grid installation would operate as follows:
- Solar production > Installation demand: Solar production will cover the installation's consumption, and the surplus will charge the batteries.
- Solar production < Installation demand: Solar production and the battery cover the installation's consumption. If the battery is below a predefined percentage, the generator starts and charges the batteries up to another defined percentage while supplying the house.
For the installation and parameterization of a generator with TBB, it is strongly recommended to read the AGS Application document, available in the downloads section of TBB inverters on the Visiotech website.
Generators can come with two types of start: manual start and automatic start. Both are valid for TBB inverters, but if it is manual, the user must be present at the installation. Therefore, a generator with automatic start is the most efficient and safest for an off-grid installation.
Automatic generators contain a dry contact, which in turn must be controlled by the dry contact output that TBB inverters have (NOTE, from 5 KVA models and above. The 3-4 KVA-S can work but with manual start). When the TBB dry contact is closed, the generator starts; when it is open, the generator stops.
The connection between the generator and the inverter is made as follows: the cable with phase, neutral, and ground coming from the generator must be connected to the AC IN port of the inverter, as shown in the following image. The RS485 connection between the dry ports of both devices must be made with the S4 port of the inverter.
For parameterization, it can be done in different ways: Via the inverter's own LCD screen, via PC using the TBB-INTERFACE interface, or remotely via TBB NOVA.
Using the inverter's own LCD screen.
By default, on the LCD screen, you can see information about the battery, electrical grid, solar production, and electrical demand. To change certain parameters, the inverter must be in StandBy. Simply hold down the inverter's power button for 3 seconds (until you hear a beep and StandBy appears on the screen)
To access settings you must hold down the "ENTER" button. Using the "UP" and "DOWN" buttons, you can navigate through the settings menu.
To change a specific parameter, press the "ENTER" button, and modify its value using the "UP" and "DOWN" buttons. There are certain parameters that require the inverter to be in standby to change them; in these cases, the SETTING icon on the screen will appear off.
To confirm this modification, you must press the "ENTER" button again. If the modification was successful, the "SUCCESSFUL" icon will remain lit for 1 second. If the modification was not successful, the "FAIL" icon will remain lit for 1 second. If you want to cancel this modification (for example, by mistake), press the "ESC" button.
The parameters that need to be changed for a generator are the following:
- Parameter 30 (type of AC source). Choose 1 (Generator).
- Parameter 32 Choose 1 (Weak AC Input). This way, the inverter detects that the AC source may be fluctuating, as in the case of a generator.
Using the TBB-INTERFACE
This method is carried out using the TBB-INTERFACE (image), an adapter to connect the PC to a TBB system, therefore, it is an ideal method for local parameterization.
The TBB-INTERFACE connects to the PC with a USB adapter (PC side) - Type B (TBB-INTERFACE side) that is included. To connect it to the inverter, simply use a standard RJ45 cable, from the RJ45 port of the TBB-INTERFACE to the CommOn port of the TBB inverter.
Then you need to download the software (available on the TBB website or you can also request it from Visiotech's SAT department) TBB Linking. Once downloaded, click on the application itself:
The first interface is as follows. You must specify the device type (by default, Inverter, which is what we are going to parameterize), and click on Open
Then, in Communication Settings, as set by default (COM3 and Baud 9600), click on Open.
The resulting interface looks like this. This means communication with the inverter was successful. To parameterize the Generator input, click on AC Input.
Within AC Input, you need to change AC In Source Selection to Generator and AC Wave Harmonic Adaption to Weak AC Input. You can also see that more parameters can be changed, such as voltage and frequency ranges.
Finally, you need to save and send the changes made to the inverter, by clicking on Send Settings, All Settings, and OK. Once sent, turn off the inverter and turn it back on.
Using the TBB NOVA App (remote)
This method is very useful for installers or distributors if remote support is needed. As mentioned earlier, to have an installation on the TBB cloud (TBB NOVA) it is recommended to read the following FAQ:
Once inside the cloud (either in the App or on the web portal), select the installation you want to parameterize, and then click on Install. Once inside Install, where the settings are, go to General Setting.
Next, click on AC Input Setting.
Within AC Input Setting, go to the AC Source submenu and choose as AC Source Selection: Generator and as Allowed Low Quality AC Source: Weak AC Input. Click Save and the generator will be parameterized. Remember that the icon* shows that this parameter can only be changed with the inverter in StandBy (by pressing the power button for 3 seconds)
As you can see, you can modify values such as the maximum battery charging current, the state of charge (% SOC) at which the generator automatically starts, etc.
Using the TBB-E-MONITOR monitor
In this case, programming the generator is done locally. Once the TBB-E4-MONITOR is connected, tap on the screen on settings (red square):
Once inside this menu, tap on General Settings and then on AC Input.
Then, tap on AC IN Setting, AC Source and choose in AC Source Selection: Generator and in Allowed Low Quality AC Source: Weak AC Input.
Common Errors and Tips
A very common error is trying to use a generator but NOT having Generator mode set in AC Input, as described above. By default, AC Input is set to Grid, and it does not detect the generator nor allow charging/discharging batteries or powering the installation.
Another error that may appear is warning 23 (AC in Under Frequency Protection), which can appear on the inverter's LCD screen, the TBB-E4-MONITOR, or the NOVA App. This error can occur either when starting up or shutting down the generator (which is normal since at the start or end of operation the source frequency is low) or because the wiring (phase-neutral) of the generator is reversed. The solution is simple: just swap the phases of the cable connected to the generator's plug and the error will disappear.