If you’re installing solar on your RV, one of the first decisions is how to wire your panels. The three choices are series, parallel, or series-parallel which is a combines both methods. Here’s an easy way to understand the difference so you can choose what’s best for your RV.
Series Wiring: Higher Voltage, Easier Installation
Best when your panels are not shaded and have equal exposure to the sun.
In a series connection, the panels are linked end-to-end. The voltage adds up, but the amps stay the same. This higher voltage works really well with MPPT solar charge controllers, which like higher input voltage.
Why series is good:
- A series wiring setup keeps voltage high, which helps an MPPT controller operate efficiently for longer.
- You can use smaller (lighter gauge) cables because current (amps) stays lower.
- The roof wiring is simple, clean, and less expensive.
Main drawback:
Shading of one panel in the affects the power output of the entire string of panels (unless your solar panels include use a bypass diode or similar technology).
Parallel Wiring: Better With Shade
Best when your panels are prone to shading or get sun exposure at different times.
With a parallel connection, all the panels connect side-by-side. The voltage stays the same, but the amps add up. Each panel works on its own, so shading affects only that panel.
Why parallel is good:
- Shade on one panel does not limit the power from the others.
- Good if your panels are different ages or types.
- Great for roofs with vents, AC units, or anything that casts shadows.
Main drawback:
You need thicker, more expensive cables because the current (amps) is higher.
Which One Makes More Power?
- In full sunlight, series wiring usually produces more power under ideal conditions
- In shady areas, parallel wiring often works better because each panel has minimal affect on the other
FREE Solar Array Calculator – Easily size your MPPT Charge Controller or experiment with solar panel configurations to find the optimal setup for your RV. Works with 12V, 24V, Series / Parallel and mismatched panel configurations.
Series-Parallel Wiring: Best for Changing Conditions
Best when panels can be split between locations on your RV roof.
With a series-parallel connection, panels are split into two series-connected sets (strings). The two series strings are then connected in parallel. Each series string works on its own, so shading or limited exposure does not affect the second set of panels.
Why parallel is good:
- Good when panels are split across both sides of your RV roof
- Shade on one panel does not limit the power from the others
- Good if your panels are different ages or types
- One properly sized MPPT solar charge controller can be used instead needing one controller for each series or parallel string
- Great for roofs with vents, AC units, or anything that casts shadows
Main drawback:
A larger and possibly more expensive solar charge controller will be required.
The Bottom Line
Most RV owners using an MPPT charge controller will do well with series wiring. It’s simple, efficient, and usually gives you the most power on sunny days. The series-parallel configuration works best for larger RVs with panels split from side-to-side or front-to-back since each area will have different sun exposure at different times.
If your RV roof gets shaded or your travels take you into forests or campgrounds with lots of trees, parallel wiring may give you more reliable power throughout the day.
What makes RV solar unique is that your position will change constantly, so results will vary as you change locations. Pick the configuration that will give you the best results most of the time, and don’t be afraid to reposition your RV for the best sun exposure.
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