How much solar do I need to run a 12V fridge in an RV?

A typical 12V compressor fridge uses about 40–60W on average (cycling). Over 24 hours that's roughly 480Wh/day. In a location with 5 peak sun hours, a 100W solar panel produces about 500Wh/day — so 100W of solar is roughly the minimum to break even with just a fridge load, with no buffer. 200W gives you comfortable headroom for other loads and cloudy days.

Is 200W of solar enough for van life?

200W of solar covers a modest full-time van setup — a 12V fridge, LED lights, phone and laptop charging, and a small fan — in most of the US, most of the year. It becomes marginal in winter months in northern states or with extended cloudy stretches. 400W gives you better headroom and makes sense if you add a CPAP, larger fridge, or stay put for multiple days.

Can I have too much solar?

Practically, yes — your MPPT charge controller will simply not accept more watts than it's rated for (excess panels are wasted). And a full battery stops accepting solar regardless. Sizing to 10–20% above your calculated need is smart; going much beyond that is diminishing returns unless you're adding battery capacity to match.

How Much Solar Do I Need for My RV or Van?

The right solar panel wattage for your van or RV comes down to three numbers: how much energy you use each day, how many hours of useful sun you get in your location, and how many days of buffer you want before you need to plug in or drive.

For the full system picture, see the solar setup guide. For panel recommendations, see best solar panels for RV & van builds.

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Enter your daily loads and location and we'll calculate exactly how many watts you need — free.

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Step 1: Calculate your daily watt-hours

List every electrical load and estimate daily use:

Load	Watts	Hours/day	Wh/day
12V compressor fridge	50W avg	24	480
LED lighting	10W	4	40
Laptop charging	60W	2	120
Phone charging (×2)	10W	3	30
Diesel heater (fan only)	10W	8	80
Vent fan	20W	6	120
Total			870Wh/day

Your number will vary. A minimal setup (no fridge, just lights and device charging) might be 200Wh/day. A full-timer with a larger fridge, CPAP, and a laptop for remote work might hit 1,500–2,000Wh/day.

Step 2: Find your peak sun hours

"Peak sun hours" (PSH) is the number of hours per day your location receives equivalent full-sun intensity (1,000 W/m²). It's not total daylight — a cloudy day might produce only 1–2 PSH even if the sun is up for 14 hours.

Approximate average PSH by region (summer/winter):

Region	Summer PSH	Winter PSH
Southwest US (AZ, NM, SoCal)	6–7	4–5
Southeast (FL, TX)	5–6	3–4
Pacific Coast (CA, OR, WA)	5–6	2–3
Mountain States (CO, UT)	6–7	4–5
Northeast (NY, MA, ME)	5–6	2–3
Midwest	4–5	2–3
Pacific Northwest	4–5	1–2

Size for your worst-case months if you travel year-round. For full-timers following the sun, you can size for average conditions.

Step 3: Calculate solar panel wattage

Formula: Panel watts = (Daily Wh ÷ system efficiency) ÷ peak sun hours

System efficiency accounts for MPPT losses, wiring losses, temperature derating, and panel soiling — budget about 75–80% efficiency overall.

Example: 870Wh/day load, 5 PSH, 75% efficiency:

870 ÷ 0.75 = 1,160Wh from solar needed → 1,160 ÷ 5 PSH = 232W of panels

Round up to the nearest standard array: 2 × 175W = 350W gives you comfortable headroom, or 1 × 200W + 1 × 200W = 400W.

Common scenarios

Setup	Daily Wh	Recommended solar
Weekend camper, no fridge	200–400Wh	100–200W
Weekend van with 12V fridge	600–900Wh	200–300W
Part-time full-timer, moderate loads	900–1,400Wh	300–400W
Full-time with CPAP + big fridge	1,400–2,000Wh	400–600W
Full-time with induction cooking	2,000Wh+	600W+ (and large battery bank)

Sizing for shade and cloudy days

A shaded panel produces dramatically less power — even 20% shade on one cell can reduce a whole panel's output significantly. If your route takes you through heavily treed areas or overcast regions (Pacific Northwest, Northeast in winter), add 30–50% to your calculated solar need or plan on supplementing with DC-DC charging.

Solar alone won't keep up with induction cooking

An induction cooktop draws 1,200–1,800W — more than even a 600W solar system can produce at peak. If you cook on induction, plan to draw primarily from your battery for that load and recharge via solar and the alternator between meals.

Battery bank sizing

Your solar needs to be matched to a battery big enough to store a day's production and cover a cloudy day or two. A rough pairing guide:

Solar array	Recommended battery bank (LiFePO4)
100–200W	100Ah
200–400W	200Ah
400–600W	200–300Ah
600W+	300Ah+

For full battery sizing detail, see what size house battery for a van or RV? and 100Ah vs 200Ah vs 300Ah.

How many panels fit on your roof?

Before finalizing wattage, check your roof dimensions. A standard 175W rigid panel is roughly 58" × 26.5". A Sprinter 170 has roughly 90" × 70" of usable flat roof — enough for 3–4 standard panels. A shorter Transit or Promaster may fit 2–3 panels depending on skylights, fans, and antennas.