Series, Parallel And Series-Parallel At A Glance
Series wiring adds panel voltage. Parallel wiring adds panel current. Series-parallel combines equal series strings in parallel. The best arrangement depends on your panels, charge controller, cable run and roof layout.
Reconnecting the same panels does not create extra panel wattage. It changes the voltage and current presented to the controller. Actual output also depends on sunlight, temperature, shading, cable losses and the controller.
| Arrangement | Nominal Operating Voltage | Nominal Operating Current | Calculated Power |
|---|---|---|---|
| Four In Series | 80 V | 5 A | 400 W |
| Four In Parallel | 20 V | 20 A | 400 W |
| Two Series Strings In Parallel | 40 V | 10 A | 400 W |
Calculation inputs: four identical panels, each operating at 20 V and 5 A, under the same conditions.
When Series Wiring May Help
Higher array voltage means lower current for the same transmitted power. For a given cable resistance, lower current reduces resistive loss. Series wiring can therefore help with a longer panel-to-controller run, provided the controller accepts the resulting voltage.
Check the panel’s open-circuit voltage, its temperature coefficient and the lowest expected temperature before choosing a string length. Cold conditions can raise open-circuit voltage. The controller’s input limit is model-specific; an example from another model is not a safe substitute. Check Victron’s PV Array Installation Guidance.
When Parallel Wiring May Help
Parallel wiring keeps array voltage near that of one matched panel while increasing total current. It can suit a controller with a lower permitted input voltage. It also increases the current carried by shared cables and connectors, so their ratings and voltage drop need to be checked.
A shaded panel can contribute less output while other parallel branches remain active. Panel bypass diodes, shade patterns and controller tracking affect the result. Victron describes how partial shading can produce multiple power peaks. Read Victron’s MPPT Tracking Explanation.
When Series-Parallel Makes Sense
Equal series strings connected in parallel provide another voltage/current balance. Use the Series-Parallel Wiring Guide for the worked example. Confirm that the strings have compatible electrical characteristics before combining them.
Check These Details Before Buying
- Panel operating voltage/current, open-circuit voltage, short-circuit current and maximum series-fuse rating.
- The exact controller’s PV voltage, current and power limits, plus battery-voltage compatibility.
- Cable length, conductor rating, voltage drop, connector compatibility and equipment temperature ratings.
- Required disconnects, grounding and overcurrent protection from the relevant equipment instructions.
Use the Solar Panel Technical Terms guide to interpret the labels. Read the Solar Array Fusing Reference separately.
