How Much Solar Do You Actually Need on a Camper Trailer?

"100W solar" or "200W solar" gets quoted as a spec line on almost every camper trailer listing, but on its own it's a meaningless number. A 100W panel is more than enough for some buyers and nowhere near enough for others. The right answer depends on what you're running, how long you're off-grid, when in the year, and where you park.

This guide walks through the actual sums — the same three-step calculation any honest 12 V auto electrician would do — and applies them to the standard 100W roof panel on a Hip Summit or Hip Companion. By the end you'll know whether the standard setup fits your trip style, when to add a solar blanket, and how solar, battery and inverter work together.

The five variables that decide your solar need

Solar sizing on a camper depends on five things. Skip any one and the answer comes out wrong:

1. Daily energy use — how many amp-hours (or watt-hours) your fridge, lights, devices and inverter loads draw over 24 hours.
2. Real-world panel yield — what a "100W panel" actually produces in your conditions, which is far less than its rated number.
3. Battery usable capacity — how much energy you have buffered for cloudy days or shaded parking.
4. Days off-grid in a row — a weekend is forgiving; a week is not.
5. Where and when you park — shade, panel angle, latitude and season all move the number.

We'll take them in order, then run three real trips through the maths and finish with the exact standard system we ship and why.

Step 1: Calculate your daily energy use

Start with what you actually run. Camper trailer loads are usually measured in amp-hours (Ah) at 12 V, but watt-hours (Wh) make the solar formula cleaner — so we list both (1 Ah at 12 V ≈ 12 Wh). Here's what realistic loads look like:

Add your loads up and you'll land in one of three brackets:

• Weekend warrior (fridge, lights, phone charging): ~30 Ah/day (~360 Wh)
• Off-grid couple (fridge, laptop, awning light, water, some device charging): ~40–50 Ah/day (~480–600 Wh)
• CPAP user, remote worker or heavy device user: ~60–80 Ah/day (~720–960 Wh)

These numbers are the single most important input. The fridge dominates, and it draws more on hot days — so if you camp inland in summer, size to the upper end of your bracket.

Step 2: Use the sizing formula

Once you know your daily load, the panel size follows from one equation. This is the honest version of what a shop should be doing on the counter, instead of quoting a round number:

You need one more input: peak sun hours for where you camp. A "peak sun hour" is the equivalent of one hour of full 1,000 W/m² sun — the same standard test condition panels are rated at. It is not hours of daylight. Sydney gets ~13 hours of summer daylight but only 5–6 peak sun hours, because morning and evening sun is weak.

Step 2b: Peak sun hours across Australia

Peak sun hours swing enormously by city and season, and this variable moves your required panel size more than any other. The table below is rounded for planning from Bureau of Meteorology solar-exposure averages (BoM average daily solar exposure; see the BoM solar-radiation glossary for the underlying definition).

The practical rule: size for your winter figure if you camp year-round. A 100W panel that keeps you topped up in Perth in February can leave you 30–40% short in Melbourne in July. If you're a WA off-gridder chasing winter sun up north, your effective sun hours stay high; if you're a Queensland or southern-states camper heading into the cool months, plan around the low column. Our dedicated guide to winter camping in a teardrop covers the seasonal side in more detail.

Worked example: the formula in action

Take a touring couple on ~50 Ah/day (600 Wh) camping through Victoria in winter (2.5 peak sun hours):

Panel watts = (600 × 1.3) ÷ (2.5 × 0.75) = 780 ÷ 1.875 ≈ 416W

The same couple in Brisbane in summer (6.0 sun hours) needs only (600 × 1.3) ÷ (6.0 × 0.75) ≈ 173W. Same trailer, same fridge — the answer more than doubled purely on where and when. That gap is exactly why we pair a modest fixed roof panel with a portable blanket rather than bolting on one oversized array.

Step 3: Real-world solar yield from a 100W panel

The formula assumes a clean, well-angled panel. On a real camp roof, output is lower. A "100W" panel produces 100 watts only under standard test conditions: 25 °C, full perpendicular sun, no shade. In practice a flat roof-mounted 100W panel typically delivers:

• Best case (summer, open north-facing sun, no shade): 25–35 Ah/day
• Average summer: 15–25 Ah/day
• Average winter (southern states): 8–15 Ah/day
• Shaded or heavily overcast: 0–10 Ah/day

The 100W roof panel on a Hip Summit or Companion sits at the top of that range parked in open summer sun — roughly 30 Ah/day. In dense shade or persistent cloud it can produce almost nothing usable. That's not a fault of the panel; it's physics, and it's why the battery matters as much as the panel.

Step 4: The battery is your buffer

The mistake people make is thinking solar must equal daily consumption every single day. It doesn't. Battery capacity buffers the inevitable cloudy days.

The 120Ah LiFePO4 (lithium) in a Hip camper gives roughly 115 Ah of usable capacity, because lithium iron phosphate can be safely discharged far deeper than AGM. That's about two-and-a-half days of 50 Ah/day consumption with zero solar input — a genuine buffer, not a spec-sheet number.

In practice this means:

• 3–5 day off-grid trip, mixed weather: Solar barely needs to keep up — the battery carries the cloudy days and tops back up when the sun returns.
• 7+ day off-grid trip: Solar must match or exceed daily consumption averaged over the trip, or the battery slowly drains.
• Extended stationary camps: Now solar dominates, because the battery only carries you through one or two bad days, not seven.

A common pattern: people oversize panels and undersize batteries, then camp in shade for two days and run out anyway. The opposite is just as wasteful — a 300Ah battery behind a 100W panel won't recover past the first big drain without a generator or a town charge. As a rule of thumb, aim for roughly 100W of solar per 120–150Ah of lithium for touring use, which is exactly the ratio the standard Hip system ships at. We unpack the chemistry trade-off in LiFePO4 vs AGM in camper trailers.

Step 5: Three real sizing scenarios

Scenario A — Weekend coastal trips, two people, fridge + lights only

• Daily consumption: ~30 Ah (360 Wh)
• Three days off-grid, coastal NSW summer (~5 peak sun hours)
• Formula: (360 × 1.3) ÷ (5 × 0.75) ≈ 125W ideal
• Solar over 3 days from 100W: ~75 Ah; total trip use ~90 Ah; net battery draw only ~15 Ah of 115 usable

Verdict: the 100W roof panel is comfortably enough. The battery never gets near its floor.

Scenario B — Week-long inland trip, two people, laptop/CPAP, mixed weather

• Daily consumption: ~60 Ah (720 Wh)
• Seven days off-grid, inland winter-ish (~3.5 peak sun hours)
• Formula: (720 × 1.3) ÷ (3.5 × 0.75) ≈ 357W ideal
• 100W over 7 days averages ~140 Ah; trip use ~420 Ah — a ~280 Ah shortfall, well beyond 115 usable

Verdict: 100W is not enough on its own. Add a 120–200W solar blanket (deploys in unshaded sun even when the camper is parked in shade), or accept town/generator top-ups mid-trip.

Scenario C — Two-week extended stay, family of three, shaded forest camp

• Daily consumption: ~70 Ah (840 Wh, more device charging)
• Roof panel often in shade; effective yield ~5–10 Ah/day
• Formula at 2.5 effective sun hours: (840 × 1.3) ÷ (2.5 × 0.75) ≈ 582W ideal

Verdict: 100W is essentially decorative here. You need a 200W+ blanket you can move into sun, plus disciplined load management, or this becomes a generator trip. This is the sort of setup that suits genuinely self-contained free-camping.

Six common solar-sizing mistakes

Most undersized (and oversized) systems come from the same handful of errors. Avoid these and your first system will also be your last:

1. Sizing for summer, camping in winter. The single most common mistake. A 100W setup that's ample in Queensland in December can leave you flat in Victoria in August. If you cross more than a couple of states, size for the lowest expected sun hours (2.5–3.5).
2. Treating rated watts as real watts. A "100W panel" only makes 100W under lab conditions. Real midday output in Australian summer is typically 65–80% of the sticker before controller and cable losses — which is exactly what the 0.75 factor in the formula accounts for.
3. Ignoring heat derating. Cells lose roughly 0.3–0.5% of rated output per °C above 25 °C. A dark roof at 40 °C ambient can push panel temperature to 65–75 °C, trimming 12–25% off the rated figure. An air gap under a rigid panel helps; flush-mounted flexible panels run hotter.
4. Forgetting one shaded cell kills the string. Cells are wired in series, so a single shaded cell — a gum branch, a roof-rack bar, an awning arm — can slash the whole panel's output. Park the panel (or blanket) where it gets clean sun from about 9 am to 3 pm.
5. Pairing a cheap PWM controller with a decent panel. A PWM controller can waste 20–30% of the energy an MPPT unit would harvest. On anything 100W or larger, MPPT pays for itself in a season (the Hip system runs MPPT as standard — more below).
6. Undersizing the cable. A long thin run from panel to battery bleeds output as voltage drop. It's the cheapest part of the system to get right and the most annoying to fix later.

What a solar upgrade costs in Australia (2026)

If you're pricing panels yourself — either to supplement a fixed roof panel or to understand what's baked into a camper's price — here's the realistic Australian retail picture in mid-2026. These figures are panel plus controller and mounting hardware only; the battery is separate, and understanding the full cost of owning a camper trailer is worth doing before you spend.

For most buyers, the cost-effective path isn't a giant fixed array — it's a right-sized roof panel plus a folding blanket you deploy only when you need it. That keeps weight and cost down and covers the shaded-camp case a fixed panel can't.

The standard Hip solar system — and why 100W

Both models share the same standard 12 V system. It's designed around a two-night to one-week off-grid use case for a couple, where 100W matched to 120Ah lithium covers the realistic load with margin:

Going larger as standard would add cost and weight for buyers who'd never use the extra capacity. For those planning longer or shadier trips, the cleanest upgrade is a portable solar blanket via the +$100 Anderson-plug add-on: a 200W folding blanket lives in the storage bay, comes out when you park in shade, and adds roughly 80 Ah/day of generation potential in mid-summer. That's the configuration we recommend for serious off-grid use — far better value than oversizing the roof panel. You can add it (or leave it off) in the 3D configurator, and it's covered in what's included with the Summit and Companion.

MPPT vs PWM controllers — the hidden 25%

Camper trailer solar runs through a charge controller, either PWM (cheaper, ~70% efficient) or MPPT (dearer, ~95% efficient). The Hip system uses MPPT as standard. The practical difference is roughly 25% more usable energy from the same panel — meaningful, not transformative. If a competitor's camper uses PWM where you'd assumed MPPT, that 100W panel behaves more like 75W in real conditions.

It's worth checking on any quote. Some suppliers don't advertise the controller type unless you ask — the same way they won't always volunteer that "solar-ready wiring" means the panel isn't actually included.

How to do your own sizing in five minutes

The whole article, condensed to a checklist you can run on the back of an envelope:

1. List your loads. Fridge, lights, charging, inverter use — in watts.
2. Multiply by hours. Add them for daily watt-hours.
3. Look up your peak sun hours. Use the winter figure for your region if you camp year-round.
4. Run the formula. Panel watts ≈ (daily Wh × 1.3) ÷ (peak sun hours × 0.75).
5. Check the battery buffer. Can it carry you through your worst expected day or two of no sun?

For most Australian buyers doing 2–7 day off-grid trips with a normal load (fridge, lights, phones, occasional laptop), 120Ah LiFePO4 + 100W roof solar + an optional 200W blanket is the cost-effective combination. For extended stays, heavy inverter use, or persistently shaded camps, you'll need more battery or more solar — and almost always both. If you're weighing whether a teardrop suits your travel style at all, our take on whether a teardrop camper is worth it and the broader off-grid solar, water and power basics are good next reads.

Frequently Asked Questions

Next step

Solar is one chapter of the system — the battery it feeds, charging while you drive, the inverter and the wiring rules all interact. Our complete teardrop power systems guide connects the pieces, and every Hip build is finished and inspected in Melbourne, then certified for Australian roads through the RAV before you register it in your own state.

If you're trying to work out whether the standard 100W setup actually fits your trip style, send through a rough description: trip length, two people or a family, where you typically park, and any heavy loads (CPAP, laptop, Starlink). We'll tell you honestly whether the standard 100W is enough or whether you should plan to add a blanket from day one — the same advice we'd give a mate. You can also see current stock and build slots or read the full FAQ.

Spots in each release are limited. Get in touch via the contact page, or build and price your camper in the 3D configurator.