N-Type vs P-Type Solar Panels: The Smart Upgrade When Roof Space Is Tight

If you own a caravan, RV or boat, you probably don’t care about solar “cell chemistry”. What you do care about is simple:

More usable power from the same bit of roof.

That’s getting harder to achieve. Power use keeps climbing (bigger fridges, Starlink, induction cooking, lithium battery charging), but roof space doesn’t. So the conversation has moved on from “mono vs poly” to choices that can genuinely change daily energy production and how well a panel holds up over time.

What N-type and P-type actually mean (in plain English)

Both N-type and P-type panels are built from crystalline silicon solar cells. The key difference is how the silicon wafer is “doped”, a controlled process where tiny amounts of other elements are added so the silicon conducts electricity in a particular way.

P-type cells typically use a boron-doped silicon base (the wafer is “positive” overall). A thin layer is then treated to form the p-n junction needed for current flow.

N-type cells typically use a phosphorus-doped silicon base (the wafer is “negative” overall). A corresponding layer is treated to form the same p-n junction, just built from the opposite starting point.

That one choice, boron base vs phosphorus base, influences how a cell behaves under light exposure, heat, and ageing. And those are exactly the conditions your panels face on a caravan or marine roof every day.

Why this matters more off-grid than on a house

On a grid-connected home, small drops in panel performance are easier to ignore because the grid fills the gap.

Off-grid systems don’t have that safety net. When output drops, you feel it fast:

• Batteries reach absorption less often
• Fridges work harder
• Inverters hit low-voltage cut-outs sooner
• “We used to be fine” turns into “Why can’t we keep up anymore?”

Mobile setups make this even more important:

• Roof space is fixed
• Panels run hot
• Partial shading is common
• Mornings and afternoons matter as much as midday

So it’s not just about the number on the label (STC watts). It’s about real daily energy and how well that performance holds up as time goes on.

The hidden cost in many P-type panels

Panel wattage isn’t the whole story. How well a panel holds that wattage matters just as much.

Boron-doped P-type cells can be susceptible to boron-oxygen light-induced degradation (BO-LID), an early-life performance drop often cited around 1.5 to 2.5%.

In a space-limited off-grid system, that “small” loss can be the difference between:

• Batteries reaching full charge or not
• Running higher-draw appliances confidently or avoiding them
• A system that keeps up vs one that slowly falls behind

Another mechanism often discussed in P-type and PERC designs is LeTID (light and elevated temperature induced degradation), particularly relevant on hot, roof-mounted installs.

Why N-type has become the premium default

N-type platforms have become popular in high-efficiency panel designs because they’re built to perform well where off-grid systems actually live:

• Better stability over time, with reduced susceptibility to certain early-life loss mechanisms
• Stronger real-world yield in heat, because hot roofs punish average hardware
• Excellent low-light response in mornings, afternoons and changing weather
• Good performance density, meaning more energy per square centimetre when roof space is fixed

A practical way to choose (without getting stuck in chemistry)

Here’s a simple way to think about it.

P-type can still make sense when:

• You have plenty of roof space
• Budget is the main driver
• The environment is relatively mild
• You’re comfortable trading lower upfront cost against long-term yield

N-type is usually the smarter choice when:

• Roof space is tight and every square centimetre counts
• The install will run hot (dark roofs, minimal airflow, inland touring)
• You want maximum daily kWh, not just a bigger “watts” number
• You want to reduce the chances of your system feeling like it “doesn’t keep up like it used to”

Put simply: P-type is the value play when you can oversize. N-type is the performance play when you can’t.

N-type TOPCon in mobile-specific panel design

As N-type TOPCon has matured, it’s increasingly being used in panels designed specifically for caravan and marine installs, rather than being a resized residential panel.

N-type TOPCon cells paired with mobile-optimised electrical layouts aim to deal with real roof problems: heat, mixed light, and partial shading.

Panels such as Exotronic’s Fusion range use N-type TOPCon cells (stated up to approximately 25.2% cell efficiency) combined with three-string, parallel-wired module designs. Electrically segmenting the panel helps limit how much one shaded area can drag down total output, so shade over one section doesn’t disproportionately suppress everything.

Partial shading: what N-type does and doesn’t solve

It’s worth being clear: cell polarity alone doesn’t magically improve shade tolerance. Both N-type and P-type cells perform poorly when shading hits at the cell level.

Shade resilience is mostly driven by:

• String segmentation
• Bypass topology
• Series and parallel layout decisions

Where some N-type TOPCon panels stand out in real use is by combining the cell tech with module-level design choices that better match RV roof reality, including hatches, air con units, racks and antennas creating shifting partial shade throughout the day.

How this shows up in a real mobile panel

A practical example mentioned above is the Exotronic Fusion approach: N-type TOPCon cells paired with a mobile-first layout designed for steadier output in heat, mixed light and partial shading.

Triple shade resistance on the 220W and 250W Exotronic Fusion panels

Partial shading is common on RV roofs, including hatches, awnings, air con units, racks and antennas, usually at the worst time. These panels use three independent cell strings wired in parallel, so if one section is shaded, the other sections can continue producing power with less impact.

Bottom line

P-type panels still have a place in value-driven builds where you can afford to cover more roof area.

But for modern off-grid setups, where you want more output from less roof space and where heat and touring conditions punish average hardware, N-type TOPCon is increasingly becoming the sensible default thanks to its stability, degradation behaviour, and stronger real-world energy yield.