Solar
Solar Panels in Series vs Parallel: How to Wire Them Correctly
Short answer
Connecting panels in series adds their voltages and keeps the current the same. Connecting them in parallel adds their currents and keeps the voltage the same. The right arrangement depends on the inverter or charge controller's voltage and current limits, so strings are designed from the datasheet, not guessed.
The basic rule
| Connection | Voltage | Current | Typical use |
|---|---|---|---|
| Series | Adds up | Same as one panel | Reach the voltage an MPPT inverter needs |
| Parallel | Same as one panel | Adds up | Increase current, for example with low-voltage controllers |
| Series-parallel | Adds in each string | Adds across strings | Larger arrays with several strings |
Example
Four panels each rated about 40 V open-circuit and 13 A short-circuit, wired in series, give about 160 V at 13 A. Wired as two parallel strings of two, they give about 80 V at 26 A. The inverter datasheet states the allowed range for each.
Design checks
- Maximum input voltage must never be exceeded, including on cold mornings when panel voltage is higher.
- The string voltage should sit inside the MPPT operating window for most of the day.
- Maximum input current per MPPT input must not be exceeded.
- Use panels of the same model in one string.
- Avoid shade on part of a series string, because it can drag down the whole string.
- Use proper PV cable, MC4-compatible connectors, DC isolators and fuses where required.
Leave it to a professional
DC wiring can be dangerous because panels produce voltage whenever there is light. See our solar installation service and the inverter selection guide.
Common questions
Is series or parallel better?
Neither is better by itself. The choice depends on the inverter or charge controller. Most modern MPPT systems use series strings.
Why does shade affect the whole string?
In a series string the same current flows through every panel, so the weakest panel limits the string.
Can I mix different panels?
Avoid it within one string. Different models can have different currents and waste power.