300W Solar Panels: Output & What They Power
A popular, cost-effective size for campervans, boats and 12V off-grid setups. Here’s what a 300W panel produces, what it runs, and which type to choose.
The short answer
A 300W solar panel generates roughly 1.2–1.5kWh on a good UK summer day (much less in winter) — enough to charge phones and laptops, run LED lighting, a small fridge or cool box, fans and a water pump, and keep a leisure battery or power station topped up. It’s a popular, cost-effective size for campervans, motorhomes, boats and 12V off-grid setups, comfortably covering the basics for one or two people.
It comes in rigid (durable, permanent), flexible (curved roofs) and foldable (portable) types, costing roughly £70–£350+. One thing to know: 300W was once a common rooftop wattage, but modern home panels are now 400–450W — so if you’re researching home solar, that’s a different setup we’ll point you to below. First, the portable picture.
What this guide covers
The 300W panel is a sweet spot for smaller portable and off-grid setups — enough power to be genuinely useful, at a friendly size and price. It’s a common choice for campervan builds and 12V systems. Here’s what it’ll actually do for you and how to pick the right one.
What can a 300W solar panel run?
A 300W panel (with a battery to store what it makes) comfortably handles low-power needs:
| Will happily run | Won’t run directly |
|---|---|
| Phone, tablet & laptop charging | Kettle |
| LED lighting | Electric heater |
| Small fridge / cool box | Oven / hob |
| Fans, water pump | Hairdryer |
| Charging a power station / leisure battery | Air conditioning |
The rule of thumb: 300W is great for electronics, lighting, refrigeration and charging, but not for high-power heating appliances (kettles, heaters, ovens) which draw far more than it can supply. Paired with a leisure battery, it covers most day-to-day off-grid essentials for one or two people nicely.
How much power does a 300W panel produce a day?
| Conditions | Typical daily output |
|---|---|
| Bright summer day | ~1.2–1.5kWh |
| Average spring/autumn day | ~0.6–1.0kWh |
| Dull winter day | ~0.3–0.6kWh |
The honest headline is the seasonal swing: a 300W panel might make ~1.5kWh on a bright summer day but only a few hundred watt-hours in dull winter, because UK winter daylight is short and weak. A rough estimate: panel wattage × effective sun-hours — 300W over ~4–5 good summer sun-hours ≈ 1.2–1.5kWh. This big summer-winter gap is why year-round off-grid users often add a second panel or size up the battery.
Rigid vs flexible vs foldable 300W panels
300W panels come in three main forms — the right one depends on how you’ll use it:
| Type | Best for | Trade-off |
|---|---|---|
| Rigid (glass + frame) | Permanent campervan/off-grid mounting | Most efficient & durable; heavier, flat only |
| Flexible | Curved van roofs, low profile | Bends to fit; less efficient, shorter life |
| Foldable / folding | Grab-and-go portable use | Packs away; set out each time |
Rigid panels are the most efficient and long-lasting — the default for a permanent campervan roof or off-grid frame. Flexible panels bend slightly to fit curved roofs and sit low, but usually trade some efficiency and lifespan for it. Foldable panels fold up for storage and are set out when needed — ideal for occasional or fully portable use with a power station. Match the type to the job.
300W for campervans & 12V off-grid
Why 300W is a popular campervan size
300W is one of the most popular sizes for campervans, motorhomes and 12V systems, and for good reason: it comfortably keeps a leisure battery topped up for lighting, a fridge, water pump and phone/laptop charging — the essentials for one or two people touring, especially spring to autumn. Pair it with a suitable leisure battery (a 100Ah lithium battery is a common match) and an MPPT charge controller (which extracts more from the panel than a cheaper PWM type) and it’s a well-balanced, cost-effective off-grid setup. Heavier users — running a compressor fridge year-round, or wild-camping through winter — might step up to 400W or add a second panel, but for typical touring and weekend use, 300W hits a lovely balance of power, size and cost. It’s enough to be genuinely free of hook-ups for everyday needs.
Prices & battery pairing
Prices vary by type and brand:
- Standard rigid 300W panel: ~£70–£160.
- Flexible / foldable 300W: often more, especially branded portable kits.
- Premium portable brands (Renogy, Victron) & foldable kits: £150–£350+.
- Full kit (panel + charge controller, or with a power station): more again.
For battery pairing, a 300W panel commonly goes with a ~100Ah leisure battery — increasingly lithium (LiFePO4), which offers more usable capacity and a longer life than traditional lead-acid. As always, very cheap panels can cut corners on durability, so balance price against how you’ll use it. Check actual specs and reviews rather than wattage alone.
Wait — 300W for a house roof?
A useful point to clear up. 300W was once a common wattage for rooftop solar panels a few years ago — but modern residential panels have grown to 400–450W each. So “300W solar panel” today almost always means a portable/campervan panel, not a current home-roof panel. Two different things:
- A single portable 300W panel — for a campervan, boat or 12V off-grid use (what most of this guide covers).
- A home rooftop system — where you’d have many modern 400W+ panels wired into a full grid-connected array, sized in kilowatts.
If you’re actually researching solar for your house, a single 300W panel isn’t the unit to think about. Our guides on system sizes and how many panels fit your roof are the right starting point, and a free quote gets a home system designed properly. For portable and off-grid 300W use, read on — and see our companion guides on 100W, 200W and 400W panels for other sizes.
300W panels: the honest summary
✓ Great for
- Campervans, motorhomes, boats, 12V off-grid
- Lighting, fridge, charging, power stations
- 1–2 people’s essentials, spring–autumn
- ~1.2–1.5kWh on a good summer day
- Cost-effective; rigid, flexible or foldable
✗ Not for
- Kettles, heaters, ovens (too high-power)
- Heavy year-round/winter off-grid use alone
- Thinking of home solar as a single panel
- Relying on winter output (drops sharply)
- Cheapest panels if you need durability
Frequently asked questions
What can a 300W solar panel run?
With a battery: phone/laptop/tablet charging, LED lighting, a small fridge or cool box, fans, water pump, and topping up a power station or leisure battery. Not high-power appliances like kettles, heaters or ovens. Great for campervan and 12V off-grid essentials for 1–2 people.
How much power per day?
Around 1.2–1.5kWh on a bright UK summer day, but only ~0.3–0.6kWh on a dull winter day. Estimate as wattage × effective sun-hours (300W × ~4–5 summer hours ≈ 1.2–1.5kWh). Winter output drops sharply.
Is 300W enough for a campervan?
For many, yes — a popular, cost-effective size keeping a leisure battery topped up for lighting, fridge, pump and charging for 1–2 people, especially spring–autumn. Heavy or winter users might prefer 400W or a bigger battery.
What’s the difference from a rooftop panel?
Portable 300W panels are smaller standalone units (often flexible/foldable) used with a leisure battery. Modern home-roof panels are 400–450W, wired into a full array. 300W was once a rooftop wattage but home panels have grown — for home solar think in kilowatts, see our sizes guide.
How much does a 300W panel cost?
~£70–£160 for a standard rigid panel; flexible, foldable and branded portable versions (Renogy, Victron) often £150–£350+. Full kits with a controller or power station cost more. Cheap panels may cut durability corners.
What battery do I need with it?
Commonly a ~100Ah leisure battery — increasingly lithium (LiFePO4) for more usable capacity and longer life than lead-acid. Size depends on your usage; an MPPT charge controller is recommended to get the most from the panel.
A cost-effective campervan & 12V favourite
The bottom line: A 300W panel is a useful, cost-effective size for campervans, boats and 12V off-grid living — ~1.2–1.5kWh on a good summer day, enough for lighting, a fridge and charging with a battery. Pick rigid for permanent mounting, flexible for curved roofs, foldable for portability, and pair with a ~100Ah lithium leisure battery. Just remember: for home solar, modern panels are 400W+ and you’d size a whole system, not one panel.
Researching home solar? Get free quotes →The verdict
The 300W solar panel is a genuinely useful, cost-effective size in portable and off-grid solar — a popular pick for campervans, motorhomes, boats and 12V setups. It produces around 1.2–1.5kWh on a good UK summer day, comfortably runs lighting, a fridge, charging and a leisure battery for one or two people, and comes in rigid, flexible or foldable forms. Step up to 400W or add a panel if you’re a heavy or year-round winter user.
The one thing to keep clear: 300W was once a rooftop wattage, but modern home panels are 400–450W, so if you’re really researching home solar, you’re looking at a full multi-panel system, not a single panel — our roof and sizing guides (or a free quote) are the place to start. For everyone kitting out a van or off-grid setup, a good 300W panel is an excellent, budget-friendly choice — just match the type and battery to how you’ll use it.
Important
Going Solar UK is an introduction service for home solar installations, not a retailer of portable panels. Output figures and prices here are indicative 2026 generalisations and vary by panel, brand, weather, angle and location. For home rooftop solar, always get a professional assessment and quotes from MCS-certified installers. Portable and off-grid setups should follow the manufacturer’s guidance and be installed safely.
We may receive a commission when we introduce you to an installer, at no cost to you. Any contract for work is directly between you and the installer.