RAM ProMaster Solar Calculator
The ProMaster's wide, boxy roof is a solar dream: panels lie flat and the extra width means fewer awkward gaps. Its front-wheel drive and square walls make it a favorite for DIY full-timers. Plan generous solar and a 300–400 Ah LiFePO4 bank if you cook electric or run air conditioning on the road.
Roof space: The widest roof of the class, 65–95 sq ft, friendly to 500–800 W.
Fitting panels to a RAM ProMaster
The ProMaster's flat, wide roof is the friendliest in the class for panels, because the width often takes panels mounted crosswise, which wastes less area than lengthwise mounting on a narrower van. The trade-off is height: the ProMaster is a low-roof-clearance vehicle by design, so adding tall tilt brackets can push you past parking-garage limits. Most owners mount flat and add watts instead of tilting.
Solar alone, or solar plus alternator?
ProMaster builds frequently include a microwave or induction hob, which are short, sharp loads rather than steady ones. Those spikes size the inverter and the battery-to-inverter cable, not the solar array. Size panels from daily watt-hours and size the inverter from the single largest simultaneous load.
A representative RAM ProMaster build
Based on the preset loads below (1,965 Wh/day at 4.5 peak sun hours).
- Daily energy
- 1,965 Wh
- Solar array
- 583 W
- Battery (LiFePO4)
- 410 Ah
- MPPT
- 80 A
- Wire & fuse
- 2 AWG · 175 A
- Est. cost
- $2,003–$5,843
Adjust the preset below for your exact appliances, location, and cold-weather needs. The calculator recomputes everything live.
Quick start with a profile:
Your daily loads
Add each device with its watts and hours per day.
No loads yet. Add your fridge to start, or pick a profile above.
Solar array
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Add loads to size your array.
Show the math
Battery bank
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Show the math
Charge controller (MPPT)
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Show the math
Inverter
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Show the math
Battery-to-inverter wire & fuse
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Show the math
Estimated cost
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Budget street price → premium brands.
Itemized breakdown
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Free to use on your own site — just keep the credit link. Sizing and options.
Next steps for your RAM ProMaster
- Compare battery chemistry in the LiFePO4 vs AGM guide.
- Check your region's sun with the location pages.
- Get the wire right with wire gauge sizing.
- Work through the full pre-purchase checklist.