Solar for RVs and motorhomes

A residential panel is about 400 W and 20 square feet. An RV roof is a smaller version of the same problem with more obstacles: air-conditioner shrouds, vents, a satellite dome, and the ladder all eat area, and the panels lie flat rather than tilted toward the sun. Most Class B vans end up with 200–400 W; a Class A or a long fifth wheel can carry 600–800 W, occasionally more with the smaller RV-format panels that fit between the roof hardware.

Flat mounting costs you production, especially in winter when the Colorado sun sits low. In summer at Front Range latitude a flat 400 W array on a clear day yields roughly 1.6–2.2 kWh; in December closer to 0.6–1 kWh, and nothing at all under an inch of snow. Rough market pricing for panels, mounting, and a charge controller runs about $1–$2 per watt before an RV shop’s labor, and prices vary widely.

The battery decides more than the panels do. A pair of 6-volt golf-cart lead-acid batteries gives about 200 amp-hours, of which you should only use half, so roughly 1.2 kWh of practical storage. A 200 Ah lithium iron phosphate (LiFePO4) bank gives you nearly all of its 2.5 kWh, weighs half as much, and tolerates thousands of cycles. That difference is why nearly every serious rebuild goes lithium now.

The catch for Colorado is cold. Lithium cells should not be charged below about 32°F, so a bank in an unheated compartment needs a heated battery or a low-temperature cutoff in the charge controller. Lead-acid tolerates cold charging but loses a large share of its capacity below freezing. Either way, a September night at 10,000 feet on Cottonwood Pass will test whatever you installed.

Match the inverter to the biggest thing you actually want to run on battery, not to the biggest thing in the rig. A 1,000–2,000 W pure-sine inverter covers a laptop, a TV, a coffee maker in short bursts, and phone chargers. A 3,000 W unit adds a microwave or a hair dryer. Every step up costs money and, more importantly, idle draw: a large inverter left on can burn 20–40 W doing nothing, which is 0.5–1 kWh a day quietly gone.

A rooftop RV air conditioner draws roughly 1.2–1.5 kW while running, with a startup surge above that. Run it for six hours and you’ve used 7–9 kWh, which is more than a typical roof array makes in three good days. Soft-start kits and 12-volt AC units improve the picture, but on a 400–800 W roof the sensible plan is still shore power, a generator, or parking in the shade at elevation where you rarely need it. The fridge on propane, LED lights, the water pump, a fan, and electronics are what solar runs well.

Colorado is good RV solar country. Thin, clear air at elevation means stronger sun than the same latitude at sea level, and cooler panels run more efficiently. Dispersed camping on national forest and BLM land — typically limited to 14 days at a site, verify with the field office — is where an array earns its keep, since there’s no hookup and generator hours are often restricted or simply unwelcome.

Hail is the trade-off. Rigid panels use tempered glass and most are tested against roughly 1-inch hail, but Front Range storms regularly exceed that, and flexible panels have no glass at all. Park under cover when a storm is forecast, and check your insurance language on roof-mounted equipment. Winter brings the other limit: short days, low sun, snow that has to be brushed off, and lithium that won’t accept a charge until it warms up.

If the RV lives in your driveway between trips, it’s a small but constant load on your house: the converter keeps the house batteries topped, and in summer many owners run the fridge and AC on shore power to keep the rig ready. A 30-amp (TT-30, 120 V) or 50-amp (14-50, 240 V) RV outlet at the pad is ordinary home electrical work, and the 14-50 is the same receptacle many EV chargers use, so it fits naturally into a solar or EV-charger project.

Solar on the house then offsets whatever the RV draws while parked, under your utility’s net-metering rules. We size the array to your annual usage, so if the rig adds a few hundred kWh a year, we count it. What we won’t do is touch the vehicle itself — no roof panels, no house-battery upgrades, no inverter wiring. An RV shop or a mobile RV technician is the right call for that, and a good one will size from your real loads rather than from a kit.