I'm designing a "solar RV" built from a cargo trailer with PV panels mounted on the roof. Currently, I'm listing the expected electrical loads so I can size the solar system and battery bank appropriately.
The largest load will be a ductless mini-split air conditioner, likely a Mitsubishi 6,000 BTU, 33.1 SEER unit. It's the smallest on the market, but it should be plenty since the RV will only be ~110-130 square feet. I expect to use it frequently on shore power, but I'd like to be able to run it at least part-time while off-grid.
I've searched extensively for real-world energy usage reports from people who own that model (or similar), but haven't found any, so the next step is to estimate based on the available specs. Wikipedia describes how to calculate energy consumption based on BTU, SEER, and hourly usage, but the latter confuses me – at least in terms of how it applies to mini-splits.
My understanding is that many inverter compressor models (including the Mitsubishi) are constantly running, and modulate the compressor load as needed to maintain the desired temperature.
Does that mean I'd simply calculate energy consumption based on 24 hours/day (a 100% duty cycle)? So:
6,000 BTU / 33.1 SEER * 24 hours/day = 4.35 kWh/day
Or, is it more complicated than that? It would seem so, as that would be equivalent to a unit with 1/3 the efficiency operating for 1/3 the time, which seems fairly typical in the real world:
6,000 BTU / 11 SEER * 8 hours/day = 4.36 kWh/day
Surely the mini-split must use significantly less power than such a unit?
Best Answer
I doubt that any PV array which would fit on this camper could power this a/c unit. The power consumption of the a/c unit is far above what a small PV array could supply. Based on my recollection of the circuit requirements of room a/c units rated at 5000 BTU/h, when running, this unit will draw about 10 A at 120 V ac so 1.2 kW continuously.
EDIT
One sees campers with 5000 BTU/h a/c units on top. I have always assumed that these were only for use in campgrounds with electric plug in sites.