Be careful not to touch the electrical wires on the solar panel. When reconnecting the solar panel, make sure that the disconnect switch is in the “off” position before connecting the wires.
Wiring solar panels together can be done with pre-installed wires at the modules, but extending the wiring to the inverter or service panel requires selecting the right wire. For rooftop PV installations, you can use the PV wire, known in Europe as TUV PV Wire or EN 50618 solar cable standard.
What happens if you wire solar panels together incorrectly?
Wiring solar panels together incorrectly can lead to damaging or destroying valuable components — it can even be life-threatening. The total output voltage and current of your array are determined by how you connect the individual PV modules to each other and to the solar inverter, charge controller, or portable power station.
Minimize the length of the solar system wiring run. Be strategic in the inverter placement. AC wiring from the inverter to service panel is often more vulnerable to voltage drop than high voltage DC wiring that run from the panels to the inverter or controller.
Most modern photovoltaic systems for residential or portable use don't actually require much “wiring.” At least not in the traditional sense of soldering circuits together. The majority of solar panels and balance of system components use standardized connectors and cables, such as the Universal Solar Connector.
Although there are many different approaches to solar panel wiring, most PV installations feature: Series wiring in which each solar panel's positive terminal connects to the next module's negative terminal. Parallel wiring in which all positive terminals are connected to one another – and all negative terminals are connected to each other.
You should know that there are limitations for series solar panel wiring. In the U.S., solar strings are required to feature a maximum voltage of 600V, so solar arrays comply with article 690 section 7 of the National Electrical Code (NEC 690.7). Wiring solar panels in parallel increases the output current, while keeping the voltage constant.