Does the electrical wiring at my house/building need to be modified to install solar panels?
Installation of a solar power system does not require any new internal wiring to be provided within your home or building. Once the system components (solar panels, inverters, batteries) are interconnected the solar power is distributed to the loads within your home or building through the existing wiring. That said, modifications might need to be made to the existing wiring depending upon the type of solar power system & the requirements for distributing the solar power.
Before we understand the modifications that might be required let’s take a moment to understand the electrical wiring circuit at your home.
As shown in the schematic above, grid power supplied by the Utility company is typically fed to a distribution board at your home via the energy meter that records your monthly electricity consumption. From the distribution board electricity is distributed to appliances within your home through two primary circuits – one circuit to which all low power appliances like lighting, fans etc. are connected (e.g. 5A loads) and another circuit to which all the high power consuming appliances like ACs, heaters etc. would be connected. This segregation is typically done (at least in newer homes) as the wiring guage for these two circuits is different due to the different amounts of current flowing through these circuits.
In case of grid-tied solar systems, or, solar power systems without storage, solar power is fed to the main distribution board as shown in the schematic below. This power gets consumed by any of the appliances running at that instant and in case the solar power generation is more than the current consumption, excess solar energy is exported to the grid (under the net metering scheme). Thus there are no changes required to the internal wiring from the distribution board.
In case of hybrid solar power systems, or solar power systems with storage, solar power is provided for captive consumption or use within the home, so, solar energy needs to be fed to the circuit to which the appliances that require back-up power are connected to. As an example, in the schematic below the solar power system is installed to provide back-up power to the low power appliances only and hence being fed to the circuit containing these appliances. In case, the hybrid solar power system was installed to provide back-up power to the complete home then the solar power would’ve been fed to both the circuits, i.e. the 5A circuit to which the low power appliances are connected to and the 15A circuit to which the high power appliances are connected to. While there are no changes to the internal household wiring to the appliances from the distribution board, there might be changes to the wiring required at the distribution board due to appliances that might needed to be added or removed from the back-up circuit to which solar power is being fed to. This is often the case in older homes (more than 15 yrs old) where the segregation of the 5A & 15A loads might not have been done during the initial wiring and in such cases appropriate segregation of the loads onto the different circuits would be required for optimal performance of the solar power system.
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