A camping power setup should be sized from the energy you actually use, not from a panel-and-battery bundle that happens to be on sale. Add up your daily consumption in watt-hours, allow enough usable battery capacity for the time you expect to spend without reliable charging, and then choose enough solar to replace an average day’s use under realistic conditions.
For many Australian campsites, a fridge, lights, phones and a small water pump can land around 500–900Wh per day. A practical starting point is often a 100–150Ah lithium battery with 200–300W of solar, but heat, shade, winter sun, laptop use and other charging sources can move the answer substantially. This guide shows you how to calculate your own number.
Start with energy, not battery amp-hours
Watts, watt-hours and amp-hours describe different things:
- Watts (W) are the power an appliance is drawing at a moment in time.
- Watt-hours (Wh) are the energy it uses over time. A 20W light running for three hours uses 60Wh.
- Amp-hours (Ah) describe charge at a stated battery voltage. A nominal 12V 100Ah battery contains about 1,200Wh; a 12.8V 100Ah lithium battery contains about 1,280Wh.
Watt-hours are the easiest common unit when you mix 12V devices, USB chargers and 230V appliances. Use these formulas:
For a DC load: amps × volts × hours = Wh/day
Battery energy: battery volts × amp-hours = nominal Wh
If an appliance lists a range, use a plug-in energy meter, battery monitor or the manufacturer’s measured daily consumption. The nameplate number is usually a maximum or rated draw, not necessarily the energy used across a full day.
Step 1: Build a realistic daily power budget
List every load, its typical power draw and how long it operates. Include devices that seem small: several phones, lights and chargers can become meaningful over a multi-day trip.
| Camping load | Example assumption | Daily energy |
|---|---|---|
| 12V fridge | Measured over a hot 24-hour period | 500Wh |
| LED lights | 10W for 4 hours | 40Wh |
| Two phones | 30Wh each, including charging losses | 60Wh |
| Water pump | 60W for 30 minutes total | 30Wh |
| Laptop | 60W for 2 hours | 120Wh |
| Total | — | 750Wh/day |
A compressor fridge cycles on and off, so multiplying its maximum draw by 24 hours usually overstates consumption. Its real use changes with ambient temperature, ventilation, thermostat setting, food temperature, door openings and whether it is operating as a fridge or freezer. Measure it during conditions similar to your trip and add margin for hotter weather.
For 230V appliances running through an inverter, add roughly 10–15% to their calculated energy unless the inverter manufacturer provides a more precise efficiency figure. Also count the inverter’s standby draw if it remains switched on.
Step 2: Choose how many days the battery must cover
Battery autonomy is the period you want to operate without dependable solar, alternator or mains charging. One day may be adequate for a short trip with regular driving. Two days is a more resilient target for stationary camping. Remote trips, winter travel or tree-covered sites may justify three days or a separate backup charging plan.
Using the 750Wh/day example:
- One day of usable storage: 750Wh
- Two days of usable storage: 1,500Wh
- Three days of usable storage: 2,250Wh
That is usable energy. The battery’s advertised capacity must be higher because routinely using every last watt-hour can shorten service life or trigger a battery management system shutdown.
Step 3: Convert usable energy into battery capacity
A conservative planning rule is to use about 50% of an AGM battery’s nominal capacity and about 80% of a suitable LiFePO4 battery’s capacity. These are not universal limits: follow the battery maker’s specified depth of discharge, temperature limits and charging requirements.
For 750Wh/day and two days of autonomy:
- LiFePO4 at 80% usable: 1,500Wh ÷ 0.80 = 1,875Wh nominal. At 12.8V, that is about 146Ah, so a 150Ah battery is the mathematical minimum; 200Ah adds useful margin.
- AGM at 50% usable: 1,500Wh ÷ 0.50 = 3,000Wh nominal. At 12V, that is about 250Ah, so a 250–300Ah bank is the practical range.
Age, cold temperatures, high discharge rates and voltage drop can reduce usable capacity. Avoid treating the final one or two per cent of a battery display as guaranteed reserve.
AGM or lithium?
| Factor | AGM | LiFePO4 |
|---|---|---|
| Usable capacity for planning | About 50%, subject to specifications | Often about 80%, subject to specifications |
| Weight | Heavier for the same usable energy | Usually substantially lighter |
| Upfront cost | Usually lower | Usually higher |
| Charging | Needs a compatible lead-acid profile | Needs a compatible lithium profile and BMS |
| Best fit | Lower-cost, occasional setups where weight is manageable | Frequent travel, deeper cycling and weight-sensitive builds |
A portable power station can simplify the package by combining a battery, charger, inverter and outlets. Compare its capacity in Wh, continuous and surge output, DC charging limits, solar input voltage range and usable capacity—not just the inverter’s headline wattage.
Step 4: Size solar for the energy you must replace
A solar panel’s rated wattage is measured under standard test conditions. Campsites bring heat, changing panel angle, cloud, shade, dust, cable losses and controller losses. Peak-sun hours are not the same as hours of daylight; they express the day’s solar energy as an equivalent number of hours at full rated irradiance.
For a simple planning calculation, use a loss margin of about 1.25–1.30, then round up to a practical panel size.
With a 750Wh daily load, four effective peak-sun hours and a 30% allowance:
750 ÷ 4 × 1.30 = 244W
Rounding to 300W provides more breathing room. In good summer conditions it may recover the day’s use earlier; in cloud, winter, extreme heat or partial shade, actual harvest can be much lower.
Do not use one fixed peak-sun figure for every Australian trip. Plan for the location, season and campsite you expect, preferably using the poorer conditions you still need the system to handle. Three to four effective hours is a cautious planning range for many less favourable scenarios; five to six can occur in good open conditions, but neither is guaranteed.
Practical starting points
These ranges are planning examples, not universal prescriptions. Confirm your appliances, battery specifications and charging sources before buying.
| Camping style | Typical daily use | Battery starting point | Solar starting point |
|---|---|---|---|
| Phones and LED lights | 150–300Wh | 50Ah lithium or 100Ah AGM | 100–160W |
| Fridge, phones, lights and pump | 500–900Wh | 100–150Ah lithium or 150–250Ah AGM | 200–300W |
| Fridge/freezer, laptop and more lighting | 900–1,500Wh | 150–250Ah lithium or 300–400Ah AGM | 400–600W |
| Induction cooking or other high-draw loads | 2,000–4,000Wh or more | 300–400Ah lithium or a larger 24V system | 800–1,200W or more, plus backup charging |
Air conditioning, electric water heating, kettles, hairdryers, coffee machines and induction cooking can dominate a small system. If those appliances are essential, have the full system designed around their energy use, peak current and expected run time.
Why inverter size is only half the story
An inverter must have enough continuous output for the appliance and enough surge capacity for motor starts. The battery, BMS, cabling, fuses and connectors must also sustain the DC current.
A 2,000W appliance on a nominal 12V system draws about 167A before inverter losses. That is a very high current. Undersized cables or poor connections can overheat even when the battery has plenty of stored energy. A larger 24V system can reduce current for the same power, but it still requires competent design.
Solar controller and panel checks
The charge controller regulates panel output for the battery. An MPPT controller can generally make better use of available panel voltage than a basic PWM controller, particularly when panel and battery voltages differ, but compatibility matters more than the label.
- Keep the panel array’s open-circuit voltage below the controller’s maximum input voltage, including the rise that can occur in cold conditions.
- Ensure the controller’s current rating is appropriate for the array and battery.
- Use the correct charging profile for AGM or lithium.
- Check the battery’s maximum charge current and the BMS limits.
- Use correctly sized cable and place required fuses or circuit protection close to the energy source.
Fixed roof panels collect whenever they have sun and require little setup. Portable panels can be moved out of shade and aimed at the sun, but they take campsite space and must be packed away. A combination can work well: fixed panels provide a baseline while a portable panel improves harvest when the vehicle is parked in shade.
What reduces real-world solar output?
- Partial shade: a narrow branch shadow can cut output far more than its area suggests.
- Panel angle: a flat panel is convenient but may collect less than a panel aimed more directly at the sun.
- Heat: solar panels generally produce less power as cell temperature rises.
- Cloud and smoke: generation can fall sharply and remain low for several days.
- Dirt and damage: dust, bird droppings, cracked cells and poor connectors all affect performance.
- System losses: controllers, wiring, batteries and inverters are not 100% efficient.
Check the controller’s daily harvest rather than relying only on the panel rating. If the battery repeatedly finishes the day lower than it started, reduce consumption, improve panel placement, increase solar capacity or add another reliable charging source.
Vehicle charging changes the calculation
A DC–DC charger can replenish the camping battery while driving, which may let a touring setup use less solar than a stationary base camp. Its output still depends on drive time, charger rating, alternator behaviour, wiring and battery acceptance. A 25A charger running for two hours does not automatically deliver a full 50Ah once tapering and losses are considered.
For a system that also accepts mains charging, charge fully before departure. Remote travellers should plan for several poor-solar days and decide in advance whether driving, a generator where permitted, or reducing loads is the backup.
Installation and battery safety
- Secure batteries and power stations so they cannot move in transit.
- Keep equipment within its specified temperature range and protect it from water, impact and direct heat.
- Use cable sized for both current and run length, protect it from abrasion, and fit correct over-current protection.
- Use a battery monitor or shunt for a more useful state-of-charge estimate than voltage alone, especially with lithium.
- Do not mix batteries of different chemistry, capacity, age or state of charge unless the manufacturer explicitly supports it.
- Stop using a battery that is swollen, damaged, leaking, unusually hot or giving off an unusual smell, and follow the supplier’s safety instructions.
High-current extra-low-voltage wiring can still start a fire. If you are unsure about protection, cable sizing, earthing, ventilation or inverter installation, use a qualified installer.
Frequently asked questions
Is a 100Ah battery and 200W solar panel enough for camping?
It can be a sensible starting point for one efficient fridge, lights and phone charging, particularly with good sun or regular vehicle charging. It may be too small for hot-weather fridge use, shade, winter trips, laptops or multiple no-sun days. Calculate daily Wh and usable battery capacity before deciding.
How long will a 100Ah battery run my campsite?
A 12.8V 100Ah lithium battery contains about 1,280Wh nominally. At 80% usable, that is about 1,024Wh before wiring and conversion losses. A 12V 100Ah AGM contains about 1,200Wh nominally; at a 50% planning depth, about 600Wh is usable. Divide usable Wh by your daily consumption to estimate runtime.
Can a 200W solar panel charge a 100Ah battery?
Yes, if the controller and charging profile are compatible, but the time depends on battery state, sunlight and losses. At four peak-sun hours, a 200W array has a theoretical 800Wh input before losses. Real harvest is usually lower, so a deeply discharged battery may take more than one day while it is also powering loads.
Do I need an inverter?
Not for appliances that run directly from suitable 12V or USB outlets. An inverter is only required for 230V equipment. Avoiding unnecessary conversion usually reduces losses and simplifies the setup.
Will solar work under trees?
It will often produce something, but even partial shade can severely reduce output. A portable panel or solar blanket that can be moved into clear sun is useful when the vehicle or tent needs shade.
Final recommendation
For a typical fridge-based camping setup, start by measuring daily use rather than buying to a rule of thumb. If your total is around 750Wh/day and you want two days of storage, about 150–200Ah of LiFePO4 or 250–300Ah of AGM is a practical range. With four effective peak-sun hours, approximately 300W of solar gives a sensible recovery target with margin.
Increase capacity for winter, shade, hot weather, longer stationary stays or high-draw appliances. Reduce it only when you have reliable measured consumption and another dependable charging source.
Sources and further reading
- REDARC: How much solar do I need?
- REDARC: How much solar power do I need for a campervan?
- REDARC: How to choose a solar panel for camping
- Century Batteries: Deep cycle battery guidance
- Victron Energy: SmartShunt configuration and discharge floor
- Energy Safe Victoria: Certificates of Electrical Safety
- Energy Safe Victoria: Battery energy storage systems
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