How much solar do I need for a Class C motorhome?

Answered by RV Parts Giant · Upland, CA · October 11, 2026

Short answer: A Class C running a 12V compressor fridge, a TV and a morning coffee maker or microwave uses about 755Wh a day. Our calculator sizes that at 250W of solar, a 150Ah LiFePO4 battery and a SmartSolar MPPT 100/30 for two days parked, plus a MultiPlus 2000VA for the coffee maker. Cloudy weather pushes the array to 350W.

The Class C preset in our calculator assumes the loads most motorhome owners run once they are off hook-ups. The Class A preset starts from exactly the same list, so these numbers apply to a Class A too until you add loads of your own.

What the preset assumes

Load	Amp-hours a day (12V)
Lights, water pump, phone charging, vent fans	18
12V compressor fridge	25
TV or entertainment in the evening	8
Morning coffee maker or microwave, through an inverter	8
Total	59Ah, about 755Wh

Two days between recharges, about five peak sun hours, parked rather than driving. The math uses a 12V bank, 85% usable LiFePO4 capacity, 75% real-world solar harvest and 92% inverter efficiency.

The result

Solar: 250W. 59Ah a day is about 755Wh, and five sun hours at 75% harvest needs just over 200W, which the calculator rounds up.
Battery: 150Ah. Two days is 118Ah, and 85% of 150Ah covers it.
Controller: SmartSolar MPPT 100/30.
Inverter: MultiPlus 2000VA, an inverter and shore-power charger in one, sized for the coffee maker or microwave at about 1,500W.

The Renogy 400W 12V Starter Kit covers the 250W array with headroom, which helps on the bad days.

What changes the answer

Change	Solar	Battery	Other
Preset as above	250W	150Ah	MPPT 100/30
Three days parked instead of two	250W	250Ah
Cloudy or winter sun (about 3 peak hours)	350W	150Ah
About an hour of driving a day	150W	150Ah	Orion-Tr Smart 30A adds about 27Ah
Induction cooking inside	300W	200Ah	MultiPlus 12/3000, 1,075Wh a day

A motorhome has its own engine, which is the advantage over a towable. An Orion-Tr Smart 30A charging while you drive between sites cuts the array to 150W without touching the battery size. Induction cooking is the load that changes the inverter: it peaks around 1,800W, past what the 2000VA unit is sized for here.

Add a SmartShunt to whatever you build. It is the part that tells you whether the 25Ah fridge figure is right for your fridge in your weather.

Run your own numbers in our RV solar & battery calculator. It opens with the Class C preset filled in.