Basics of Electrical Installations
Electrical installations can be divided into several groups depending on the type of system that is going to be installed.
We can focus on two groups that are generally considered for electrical installations: Single-Phase and Three-Phase.
Single-phase or even split-phase installations are mainly focused on the residential sector, regular size houses, apartments and some small, local stores that will not demand too much power.
However, especially for commercial applications, sometimes upgrading the installation to a three-phase configuration is needed.
This involves three conductors or wires that will be related to the phases of the electrical connection, each conductor will be related to a phase.
Three-phase connections allow you to have more power available for applications that demand air conditioning, industrial or commercial purposes.
Moreover, often the three-phase connection is also used for the power supply of big houses, mansions or places that have bigger loads than a regular size house would.
In these cases, it is necessary to install a solar power system that has a three-phase connection to be integrated with the rest of the electrical installation.
Most commercially available inverters will be single-phase, but some of them can be considered for three-phase applications.
What is the Difference Between a Single-Phase and a Three-Phase PV System?
Having a good idea of what a three-phase PV system looks like is essential to understanding the components of the solar array.
First, you must know that the solar panels are the same for both cases.
All the series and parallel wiring connections between the modules are also the same, since they all work in DC.
Once the DC wiring reaches the combiner box all the wiring goes to the inverter.
On the AC side of the inverter, the connection can be either single-phase or three-phase.
If the connection is single-phase the AC output will only have two wires, while if it's three-phase, the AC output will have three wires that will represent phases A, B, and C.
What Options Do I Have To Install a Three-Phase Solar System?
There are mainly two types of options available in the market.
The first option is related to single-phase inverters that can be wired in a three-phase configuration.
Not all single-phase inverters have that capability, therefore it is essential that you check with the brand if they are suitable for three-phase configurations.
The second option is installing a three-phase inverter.
This option generally demands less wiring and fewer costs, since there is only a single device needed to execute the work of the other three devices.
The SMA Solution to the Three-Phase Market
SMA is one of the greatest inverter brands on the market.
The German brand offers three main options available for three-phase installations.
The first one is a grid-tied solution using the Sunny Boy single-phase inverter. By installing three of these inverters and wiring them together, it is possible to establish a connection between all of them and obtain a three-phase configuration.
The second option is another grid-tied solution, but using the new Sunny Tripower inverter. This device is a three-phase inverter that is able to produce a three-phase AC power output from a DC power output.
This product is an amazing option since it contains all the most recent and innovative features of the brand:
- An SMA OptiTrac feature that allows maximum power point tracking under shading conditions
- The possibility to directly couple with Tigo TS4-R DC power optimizers
- 98% efficiency to take the best advantage of your solar power production.
The second one is a good option for the off-grid market that needs to install a three-phase power system.
This configuration uses an AC coupled solution that involves combining two of the iconic models of the brand.
The first one of them is the Sunny Boy model, which is one of the original grid-tied inverters of the brand.
These devices can be synchronized together to create a three-phase configuration with the other versions, called the Sunny Island battery-based inverter.
A basic schematic of this AC coupled solution can be seen below.
We have examined the main differences between a three-phase and a single-phase electrical installation.
Moreover, we have also discovered that the DC side of the PV array does not change in function of the configuration that we have since the DC side has only positive and negative terminals.
Besides, the solar industry offers several solutions for those customers who need to have a three-phase system installed in their properties.
The most valuable and easiest of them is the one that includes a three-phase inverter device, and SMA is one of the few companies that offers both configurations.
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