29/08/2026
What Is a Solar Panel String?
A solar panel string is a group of panels connected in series, with the positive terminal of one panel connected to the negative terminal of the next. In a series connection, the voltage adds up while the current remains approximately the same. For example, ten panels with a Vmp of 40V would produce approximately 400V at maximum power.
The number of panels you can put on one string is not fixed. It is determined mainly by the inverter’s maximum PV input voltage, its MPPT voltage range, the panel’s Voc and Vmp, and the temperature at the installation site. The most important safety calculation is ensuring that the combined Voc of the string, particularly at the lowest expected temperature, does not exceed the inverter’s maximum PV voltage. The string must also produce sufficient voltage to remain within the inverter’s MPPT operating range.
String design also requires checking the current limits of the inverter. Connecting panels in series increases voltage but does not increase current. Different strings can then be connected to separate MPPT inputs, which is especially useful where panels have different orientations or shading conditions. Poor string design can result in reduced production, MPPT problems or, in extreme cases, equipment damage.
During installation, panels are securely mounted and connected in series using suitable DC cables and connectors. The completed string is checked for polarity, Voc, connections and voltage before being connected to the inverter through the required DC protection and isolation equipment. Proper string sizing is therefore not about simply counting panels; it is about matching the panels, inverter and site conditions correctly.
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