Choose a panel

For RV applications, it is often better to use a 12-volt panel due to smaller size and more robust construction. There are also reasons to consider higher voltage residential style panels, including lower cost per watt and the ability to use smaller less expensive conductors from the roof to the controller.

12V Panels

12V panel pros

• smaller and more robust
• easier to fit smaller unit(s) on available roof space
• can mount more than one in parallel, thereby allowing better power transfer. If only one panel is shaded, the other can still produce significant power
• may use less expensive PWM type solar charge controller

12V panel cons

• 12V panels tend to be more expensive per watt
• mounting more than one panel on the roof requires a combiner box
• depending upon the maximum amount of current produced, the conductor from the roof to the charge controller may need to be larger and therefore more expensive

12V panels suited for RV use are available in sizes from 100 watt up to approximately 220 watt. A 12V panel might have 36 photovoltaic cells, each producing approximately 0.46V under load. 36 cells * 0.46V/cell = 16.56V. This is known as the maximum power point (MPP) voltage.

Higher Voltage Panels (residential/commercial)

this panel has 72 cells

Higher voltage panel pros

• typically less expensive per watt
• higher voltage means the conductor from roof to charge controller may be smaller

Higher voltage panel cons

• larger residential panels are not as robust as smaller panels designed for RV usage. The larger panel may suffer damage (micro fractures or micro cracks) due to motion and vibration. The damage is not easy to detect, but will reduce the useful life of the panel
• The higher voltage of a residential panel requires the use of an MPPT type solar charge controller which may be more expensive than a PWM controller

Residential panels for RV use are available in sizes from approximately 250 watt up to 350 watt. A high voltage panel might have 60 or 72 photovoltaic cells.

Other Considerations

Solar panels for RVs and trailers can be permanently affixed to the roof, carried in the trailer and placed out in the sun when parked, or both. One issue with solar charging is shady campsites - super nice for camping in the heat of summer, but definitely impacting the amount of power to be harvested. By placing panels in the sun and by being able to move the panels as the sun moves throughout the day, solar power can be maximized. Other possiblilities include using a generator, but there are drawbacks and restrictions to consider.

Each situation will have its own nuances - what is ideal for one customer may not work well for another.  Remember, the type of panel you select is part of a larger system design. If you need any assistance choosing, please let me know!