When your solar PV system no longer meets your current electricity needs, expanding solar power is always an appealing option to reduce bills and optimize your energy consumption. As you know, the main components of a solar PV system are:

  • Solar Panels.
  • Inverter.
  • Mounting equipment. 
  • Electrical components.  

Your current solar PV system is designed for a certain capacity, so there are a few things to take into account for each system component when upgrading it. 

Standard considerations.

Adding new solar panels into your solar array is a straight forward process. You just need to make sure that the added panels are compatible with the already existing ones, what this means, is that the produced output voltage of both needs to be equal or very similar.

A recommended practice, is to upgrade the array using identical panels to those already installed, that will allow you to place them in the same array with the same inverter. However this is not always possible. In such case, is recommended to install a separated system that has its own string inverter, otherwise, differences in power and voltage will reduce the performance of the entire system. If not possible, then the only alternative solution is to find a module that has a  very similar output voltage and current to the ones you already have, however, the new modules must not be in the same string with the older models.

The next thing you want to assure is the correct installation of them. You need to verify that the roof or ground space you plan to install them on, is sufficient and able to handle the weight of the entire system. 

Likewise, you need to take special care when installing the electrical components and wiring of the panels, if possible, you should get the assistance of a certified electrician to help you comply a safe and correct installation.  

The inverter of your system. 

The main issue you encounter when upgrading your system is when you consider the inverter.

Usually, your existing inverter is sized for the capacity of your system, meaning, that if you want to upgrade the solar array, you also need to upgrade your inverter. There are two options, upgrading with a bigger string inverter, or employ several micro-inverter to every solar panel. 

String Solar Inverter 

String-Inverters are the most common in residential systems. The DC electricity generated by the solar panels is fed into this inverter and then converted into AC electricity to feed all the appliances.

These inverters are usually sized for the maximum rated capacity of the system feeding them, but their size will be mainly determined by the DC/AC ratio (typically 1.2) that the designer uses. For instance for a 6kW PV system, a 5kWAC inverter would be ideal.

You have to keep in mind that the bigger the capacity of the inverter, the more expensive it will be.

Micro-Inverters 

A micro-inverter, as the name implies, is a small capacity inverter installed on every panel of your system that tracks the maximum power point of your module and converts from DC to AC. These inverters are sized to handle the specific capacity of the panel or array. 

The main advantage of this system is that it allows you to expand the system way easily. As they are sized for their specific modules, panels can be added one at the time whenever you need to.

The downside of this technology is that the total cost of the system is generally more expensive than standard string inverters. 

Final Thoughts

Expanding a solar PV system is not complicated if you examine carefully some of these ideas. Deciding the total future capacity of the system you want can help you to decide whether micro-inverters are the right call for you.

References.

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