By connecting several solar panels in series, we can improve the total voltage, which is the sum of the voltages of each panel, to reach the voltage required by the inverter.
The voltage remains constant, equivalent to that of a single panel. However, this system is more vulnerable to shading; one dark or defective panel can significantly reduce the power output of the entire string.
In parallel, the voltage is constant, equivalent to that of a single panel, and the current increases with the sum of the currents of each panel. Individual panel failures are less frequent in this configuration; a dark or defective panel has less impact on the total power output of the system.
When should solar panels be used in series?
If you need a higher input voltage for the inverter or charge controller to work properly, panels can be used in series to increase the overall system voltage. This is essential for larger solar systems or those operating in cold weather conditions where the voltage can drop further.
When the space available to install panels is long but narrow, space can be better used by placing panels in series, allowing more panels to be connected along a run.
By connecting panels in series, wiring costs and installation complexity are reduced, as fewer parallel cables are needed and less equipment is connected.
Installations far from the point of consumption or energy storage will benefit from a series connection and its higher voltage.
When to install solar panels in parallel?
A parallel connection is preferable in environments where shadows are frequent or where lighting conditions vary considerably between panel locations. Each panel can operate independently, which reduces the influence of shaded areas on the overall system.
If the roofs have several sides facing different directions, the panels can be connected in parallel to improve the efficiency of each panel depending on its exposure to the sun, without affecting the other walls.
Parallel connection is recommended for solar systems that can be expanded in the future. There is no need to modify the existing system to add more panels, unlike a series configuration where the total voltage could exceed the inverter’s specifications.
One faulty panel does not affect the performance of the other panels in a parallel configuration. This ensures a more regular and stable power production.
Parallel connection maintains the voltage at a single panel level, while increasing the total current. This can be beneficial for applications requiring large amounts of current, such as certain pumps or motors.
The impact of weather conditions on performance
Series connection is less resistant to shading and defective panels. It is essential that each panel in a series has comparable access to sunlight to avoid a significant reduction in energy production. If there is frequent shading at the installation site or risk of partial coverage of the panels (tree leaves, dirt), it would be preferable to consider a parallel connection or the use of microinverters.
Residential or commercial solar installations located in geographically complex areas or exposed to significant environmental variations can be used in parallel. This makes the solar panels more resilient to individual variations in performance, which is essential to maintain optimal system efficiency.
Conclusion on solar panels: in series VS in parallel
A series connection is preferable if you want high voltage for your inverter and little shading of the panels. If you are concerned about shading or prefer a more robust installation against individual panel failures, choose a parallel connection.
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