Solar Efficiency for a flat-mounted array

[whatismouse]

Hi, I'm trying to get a sense if my array is outputting what it should. I have 1800watts of solar on the roof of my RV, all mounted flat. No shade obstructions. Yes, it is the middle of winter, but still, I am getting a max of around 900watts (50% efficiency). Is that pretty normal? I am in Arizona in full sun, at a latitude of 35*N. Temperatures in the 40's Fahrenheit.

 

[mopat]

I'd say a bit ab-normal. This 900 watts you're referring to is an instantaneous reading at a point in time?
Go up and cover one panel at a time (with cardboard) take some readings and see if you can find the defective panel.

 

[MattiFin]

Based on NREL calculator you could expect 59% with flat installation on Flagstaff January mid-day on "average weather" (whatever it is for Phoenix)

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

More crude way; January 1:st sun elevation angle is 32 degrees maximum and sin 32 degree would be 0.53 or 53% of rated output.

 

[whatismouse]

Ok I did get a peak wattage just over 1000watts today and given the information above, that seems normal