How to choose an RV solar kit
Count your watt-hours before you climb the ladder. Here's how the Megawatt math turns a normal day into one of four solar packs.
2 min read · Updated
Most people shop for solar by staring at their roof. That’s backwards. The roof tells you what fits. Your day tells you what you need, and the two rarely agree on the first try.
Start with a normal day
Write down what you actually run. Lights, the water pump, phones, the TV, the fridge if it’s electric, and the coffee maker you’re not giving up. The solar array calculator adds those up as watt-hours per day. Every other decision hangs on that one number.
Be honest about the air conditioner. It moves the answer more than everything else combined. In the luxury preset, leaving it checked adds about 11,000 Wh a day. Most roofs can’t make that and most battery banks can’t hold it. If you need AC off the grid, plan a generator for it and size solar for everything else.
Let the math pick the pack
The calculator divides your daily watt-hours by peak sun hours times 0.75. That 0.75 is the room it leaves for heat, wiring, and controller loss. You pick 3, 4, or 5.5 sun hours depending on the season and where you camp.
Here’s the mid-size preset as an example. It comes to 2,400 Wh a day. At 4 sun hours, the 0.75 factor leaves 3 useful hours, so you need 800 watts of panel. That’s one 800 W pack, two 400s, or four 200s.
200W solar pack
The smallest pack the calculator links. At 4 sun hours the math gives it about 600 Wh a day.
Check the current price on Amazon. Confirm the listing wattage before you buy.
400W solar pack
Two of these equal one 800 W pack, and smaller panels are easier to fit between vents.
Check the current price on Amazon. Confirm the listing wattage before you buy.
800W solar pack
Where the mid-size preset lands at 4 sun hours.
Check the current price on Amazon. Confirm the listing wattage before you buy.
1180W solar pack
The biggest single pack in the lineup. Measure twice before this one.
Check the current price on Amazon. Confirm the listing wattage before you buy.
Now go measure the roof
The original Megawatt calculator says it plainly: air conditioners, vents, and antennas eat roof space, so check the layout before you buy. Get on a ladder with a tape measure. Note every vent, the AC shroud, the antenna, and the dish if you have one.
The solar planner draws your roof from the length and width you enter and shows how many panels fit. The panel size in that drawing is a planning size you can edit. Swap in the real dimensions from the listing before you trust it.
Know when to hand it off
If the array gets big, or the battery calculator bumps you to 24 or 48 volts, you’re looking at a different charger, a different inverter, and a job for someone who does this every week. CCRV (Cross Country RV Solar) is the installer James lists on the partners page. Call them with questions. We don’t rank installers.
