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Adding solar panels to existing system

Adding solar panels to existing systems

Find out when it’s possible to add new solar panels to an existing systems and how to proceed

Is it possible to add new solar panels to an existing system? Expanding a previously installed and operational photovoltaic system is a common request, especially when household needs change.

For instance, it’s common to choose to expand the system when opting for appliances such as induction cooktops, dryers, etc., or when opting for a heat pump heating system. Additionally, it’s a choice to achieve full independence from the national power grid, saving on electricity bills.

Let’s explore whether it’s always feasible and how to manage this choice from a technical standpoint, utilizing a solar design software.

Is it possible to add solar panels to an existing system?

Those already benefiting from photovoltaic systems are aware of the numerous advantages of renewable energy. Naturally, the greater the extent and power of the system, the greater the benefits. Therefore, there might be a need to expand the existing photovoltaic system to increase its power. Is it possible?

Generally speaking, it’s possible to add one or more solar panels to an existing system, but it’s important to consider the following factors before proceeding:

  • Available space: It’s essential to verify that the roof where panels are intended to be installed is suitable in terms of space, orientation, and inclination;
  • Permits and constraints: It’s crucial to consult the relevant municipal office to identify necessary permits. It’s important to ensure there are no restrictions due to historical-landscape constraints that may limit the installation of new panels;
  • Electrical grid: Knowing the capacity of the public grid to support the additional power generated by the photovoltaic system. Generally, an increase in power up to 2-3 kW shouldn’t cause significant issues. However, beyond 6 kW, a three-phase inverter is necessary;
  • Existing system check: If the intention is to optimize the operation of the system, it may be necessary to check whether the components of the existing photovoltaic system are outdated or inefficient. If so, it might be more cost-effective to consider revamping or replacement rather than adding new panels;
  • Contract type and received incentives check: If the construction of the existing system has benefited from incentives, it might not be possible to expand the system.

Procedure for adding solar panels to an existing system

To proceed with the expansion, there are several ways:

  • Add new photovoltaic modules by connecting them to a new inverter of adequate power, obtaining two autonomous and separate systems (existing and new);
  • Add new panels and replace the existing inverter with a more powerful one, capable of managing the entire photovoltaic system and the energy produced by the panels, obtaining a single system;
  • Add the new panels by connecting them to the existing inverter if the added power is supported by the existing inverter (maximum power increase of 2/3 kW). In this case too, a single photovoltaic system is obtained.

In general, it’s also advisable to use solar design software to identify the most suitable solution based on the specifications of the system and the individual situation.


In general, the costs to add 1 kW of solar panels can vary considerably depending on several factors:

  • Quality and type of solar panels: High-quality panels tend to be more expensive but offer greater efficiency and durability;
  • Installation costs: They depend on the complexity of the project and access to the roof;
  • Incentives and benefits: Tax deductions are often available for the installation of solar panels;
  • Potential inverter cost: If it’s necessary to add or replace the inverter with a higher-power one, this cost must also be considered.

In conclusion, evaluating the addition of solar panels to an existing system requires careful planning and cost assessment, considering the various factors at play.