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Tow CalcFinanceCompare
Free Tool • Real 2026 Specs

Caravan Power and Solar
Calculator

Tick what you actually run, and we will work out the battery and solar that covers it. Then we will show you which caravans already publish that much.

1. What you run in a day

The watts and hours are our assumptions, and they are all editable. Your appliance labels beat our estimates every time.

Adjust the watts and hours yourself
12V compressor fridge
LED lights
Phones and a tablet

2. Anything from this list?

These change the answer completely, so they are kept separate.

3. How you camp

Nights between charges

Solar while you are camped

When you travel

Your answer

You use about

500 to 650Wh

a day, on the assumptions shown.
Why a range: a fridge cycles with the weather, so we size across a band instead of pretending to know.

To go 2 nights you want roughly

1,150 to 1,550Wh

of rated capacity, which is about 100 to 130Ah at 12V nameplate.

The mainstay class

1,000Wh to 1,500Wh. A fridge plus devices for a couple of days, and comfortably longer with a panel attached.

Solar to replace a day's use

150 to 200W

Assuming 5 peak sun hours a day and a 70% real-world derate for flat mounting, heat and controller losses.

What this is and is not

An estimate, built from the assumptions on this page and your own inputs. It sizes; it does not certify. We are not electricians: anything hardwired into a caravan is work for a licensed electrician, and anything involving gas is for a licensed gasfitter.

The reasoning behind every number here is in the portable power stations guide, including when a generator or more battery in the van is the better buy.

The assumptions we used

Every figure below is a rule of thumb, not a specification. They are published here because a calculator that hides its assumptions is just a number generator.

  • Usable capacity 85%. Covers recommended depth of discharge plus the losses in converting stored power to 240V. Typical manufacturer guidance, not a promise about any unit.
  • Fridge duty 33% to 50%. A compressor fridge cycles rather than running flat out. The band is where the range in your answer comes from.
  • Peak sun 5 hours in the warmer months, 4 year-round. Deliberately conservative, because the day that matters is the overcast one.
  • Solar derate 70%. Flat roof mounting rather than sun-tracking, plus heat, dust, cable and controller losses. Panels rarely make their rated watts on a caravan.
  • Amp-hours at 12V nominal. Caravans are 12V-native, and watt-hours are roughly amp-hours multiplied by volts.
  • Above 2,500Wh a day we stop sizing. Past that, a portable unit is the wrong tool and a number here would mislead.

One thing no calculator can tell you: whether your van can run a 240V appliance at all. That depends on its inverter, and a stated inverter rating is rare on a spec sheet. Ask the dealer, in writing.

Weekend size: around 500WhThe mainstay class: 1,000Wh to 1,500WhExtended off-grid: 2,000Wh and up