Campervan Solar Panel Installation & Upgrades

Campervan solar can do two quite different jobs.

For some owners, it's about keeping the leisure battery topped up and extending the time they can spend away from hookup while running a fridge, lights and other everyday equipment.

For others, solar needs to make a significant contribution to a larger electrical system with more battery capacity and higher power use.

The right solar installation therefore isn't simply the biggest panel that will fit on the roof.

We look at how much power you use, the battery capacity available to store it, the roof space available and your budget before deciding what solar will actually improve.

Thinking about adding or upgrading solar? Tell us what you have now and what you'd like your campervan to do.

How much solar do you need on a campervan?

There isn't one correct panel size for every campervan.

The useful question is what do you want the solar to achieve?

If the requirement is to run a fridge, lights and devices for longer between charges, a relatively modest solar installation can make a useful contribution and extend the time before the battery needs charging another way.

If you're trying to support a large lithium battery bank, an inverter or higher-power use over longer off-grid stays, solar needs to make a much more significant contribution.

We therefore look at:

your normal power demand;
existing battery capacity;
how long you want to stay off-grid;
other ways you charge the battery;
available roof space; and
budget.

Solar doesn't need to replace every amp-hour you use to be worthwhile.

Even when demand is greater than solar generation, the energy going back into the battery can reduce how quickly your stored capacity falls away and give you additional time off-grid.

Will solar keep your campervan battery charged?

It depends on how much power you're using and how much solar energy is available. We often explain this by thinking about the battery as stored energy. Without any charging, that energy falls away as you use the fridge, lights and other equipment. Solar puts some energy back while you're using it.

If you're consuming more than the panel is producing, the battery will still gradually discharge—but solar reduces how quickly that happens.

If solar production exceeds demand for long enough, the battery can recover charge.

This is why a useful solar system isn't designed by looking at panel wattage alone. The panel, battery capacity and actual demand all affect how long you can remain off-grid.

Do you actually need more solar?

Not necessarily.

When somebody wants better solar performance, the first question should be what is currently limiting the system?

There may already be unused capacity in part of the installation. The existing panels may be capable of producing more than the controller can accept. The controller may have spare capacity for another panel. Battery capacity may be restricting how much useful energy can be stored. Existing cabling may limit an otherwise worthwhile upgrade.

Or the existing solar installation may already be doing its job and simply can't keep pace with a much larger power demand.

Before adding equipment, we look at the capacity already available in the system and where the real restriction lies.

Sometimes more solar is exactly the right answer. But we want to establish that after assessing the existing system, rather than assuming another panel will automatically solve the problem.

When is more solar not the answer?

More solar may offer little benefit if solar generation isn't actually the thing limiting how you use the campervan.

If the battery is too small to provide the required duration, increasing battery capacity may be the better-value improvement.

If you only spend short periods away from hookup and regularly drive between stops, charging from the vehicle may contribute more useful energy than filling the roof with additional panels. And if the objective is simply maintaining a battery while the campervan isn't being used, a relatively modest solar installation may already be sufficient.

The right answer depends on what you use, how long you use it and when you get the opportunity to recharge.

Can you add more solar to an existing campervan system?

Often, but we need to look at what's already fitted first. Adding another panel isn't just a question of finding somewhere to put it.

We consider:

the existing panels;
available roof space;
the solar controller and its available capacity;
battery type and capacity;
existing cabling;
how accessible that cabling is; and
what improvement you're actually trying to achieve.

On some existing conversions, the original solar cabling isn't readily accessible. Increasing the system may then require work to reach and replace it. Experience usually allows us to find a practical route, although sometimes some visible cabling is the only sensible option.

Where an existing controller is suitable and has useful capacity available, we don't replace it simply for the sake of fitting something new.

Where changing it creates a worthwhile improvement, our preference is generally to use a suitable Victron controller.

Does a solar controller need changing when you upgrade to lithium?

Not necessarily.

The controller needs to be suitable for the lithium battery being fitted and capable of being configured appropriately. If the existing controller can do that and has sufficient capacity for the solar installation, it may be perfectly reasonable to retain it. If it isn't suitable—or if it's restricting a solar upgrade—changing it can make sense.

Lithium batteries can accept substantial charging rates, so a larger solar installation may also become more useful when there is enough battery capacity to take advantage of the energy being produced.

But again, we don't increase the solar or controller size simply because lithium makes it possible.

We look at what the complete electrical system actually needs.

How does solar work with charging while driving and mains hookup?

Solar is only one way of putting energy back into the leisure battery. A campervan may also charge from the vehicle alternator while driving and from mains hookup. These charging sources can all contribute to the same battery.

They don't necessarily have to be the same make or communicate with each other to work correctly, but each needs to be suitable for the battery and properly configured.

Where we're designing or substantially upgrading the whole charging system, we generally use compatible Victron equipment. This allows different parts of the charging system to communicate and gives us integrated configuration and monitoring.

On an existing campervan, we don't replace perfectly serviceable equipment just to make everything match.

The useful question is how much each charging source contributes for the way you actually use the van.

Rigid or flexible solar panels?

We use both. Where the roof and installation allow it, we generally prefer rigid panels. They tend to offer better longevity and performance for the money and are significantly less expensive than premium flexible alternatives.

Flexible panels become particularly useful on pop-top campervans. Weight matters on a pop-top because the roof and gas struts still need to operate correctly.

Overall roof height can matter when using height barriers, and appearance is often important because the panel sits directly on a visible roof.

A good flexible installation can therefore make more sense even though the panel itself costs more.

We buy our solar panels from Photonic Universe and look for products with good manufacturer support and warranty.

For flexible panels in particular, warranty matters. We generally look for at least a three-year warranty and can specify premium products with substantially longer warranties where the additional cost is justified.

How much solar can you fit on a pop-top campervan?

Roof size and layout determine what's practical, but significant solar capacity can be fitted to some pop-top campervans.

We've produced pop-top electrical systems with around 300–450W of solar, depending on the available roof, alongside substantial lithium battery capacity and high-power inverter systems.

One installation combined a pop-top solar system with 460Ah of lithium battery capacity, a 3kW inverter and induction cooking.

That doesn't mean every pop-top needs anything close to that specification. It demonstrates that a pop-top doesn't necessarily restrict the campervan to a small maintenance panel. The system can be designed around much greater off-grid requirements where the roof, weight and budget allow.

What affects solar panel performance?

Sunlight is the obvious answer, but several practical things affect how useful a campervan solar installation is.

Shade

Solar panels don't respond well to shading. A relatively small shadow from roof furniture, trees or something carried on the roof can have a disproportionate effect on panel output.

That's why we consider the position of roof bars, awnings, aerials and other equipment when deciding where panels can go.

Dirt

Solar panels also need to be clean. This sounds obvious, but because campervan panels are on the roof and largely out of sight, owners often forget about them.

A dirty panel can lose useful performance without the owner necessarily realising anything has changed.

Time of year and weather

Solar output isn't constant. A quoted panel wattage describes its rated output under specified conditions; it isn't a promise of what the panel will produce throughout every day.

Weather, season, shading and the position of a flat panel on a campervan roof all affect the contribution available.

We therefore treat solar as a charging contribution and design the overall electrical system around the customer's requirement rather than promising a fixed daily amount of energy from the sun.

For customers relying heavily on solar for long off-grid stays, the seasonal difference matters much more than it does for someone using solar primarily to extend ordinary battery duration.

What commonly goes wrong with campervan solar?

Solar installations are generally quite stable once correctly installed.

The most common panel failure we've encountered has been older flexible panels, particularly installations that have been in place for more than five years.

That experience is one reason we pay attention to the quality and warranty of flexible panels rather than selecting them purely on price.

How do you know whether your solar panel is actually working?

This isn't always obvious. Many campervan owners have limited battery monitoring and don't routinely know how much charge is coming in or how much energy they're using. Simple LED battery indicators can be particularly difficult to interpret. Voltage readings provide more information, but the reading is affected whenever power is being added to or taken from the battery.

With conventional batteries and simple monitoring, the clearest indication of battery state is generally when the battery has had time to settle with minimal charging or load—for example, at night when solar is no longer contributing and equipment use is low.

More sophisticated monitoring can provide much better information.

Lithium batteries with good BMS monitoring can make battery state much easier to understand, while integrated systems can show both charging and consumption.

For most customers, though, the goal isn't to spend every camping trip watching an electrical dashboard. It's to have enough power, know the system is working and be able to check it easily when necessary.

What we look at before fitting or upgrading campervan solar

Before recommending a solar installation, we want to understand what the customer is actually trying to achieve.

We look at:

current power use;
battery type and capacity;
existing solar equipment;
other charging sources;
available roof space;
roof type and weight constraints;
existing cabling and controller capacity; and
budget.

That lets us distinguish between three quite different jobs:

adding solar where none exists, increasing solar where more generation would genuinely help, or improving an existing system where something else is currently limiting performance.

We don't start with the biggest panel that will fit.

We start with what you want the campervan to do.

Solar that makes your campervan easier to use

Most customers don't want to calculate solar yield every day. They want the fridge to stay cold, their devices to work and the battery to last longer when they're away from hookup.

A good solar installation contributes to that quietly in the background.

For some campervans, that means a modest panel extending the useful duration of an existing battery.

For others, it means several hundred watts of solar contributing to a large lithium system designed for extended off-grid use.

And sometimes the best improvement isn't another panel at all.

Want to know what solar would actually add to your campervan?

Get in touch and tell us what's fitted now, how you use the van and what you'd like to be able to do for longer. We can look at the capacity already available, what is currently limiting the system and where an upgrade would make the most useful difference.

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