Paul, what kind of solar out put do you have at your barn? I like the solar idea but don't want to have to put in a huge system. I actually found something on Amazon that was a 100 watt panel wired into a floating water pump. I'm considering just trying that with a deep cycle battery and seeing how it goes.
I have three 200w Hightec Solar panels, purchased from fred480v on eBay and manufactured in Michigan City, IN.
Those panels are wired in series (63V @ 9.5A) to a Renogy Rover 40A MPPT controller, which feeds a 24V battery bank comprised of four Duracell 6V GC2 flooded lead acid golf cart batteries in series.
The batteries feed an AIMS 24V 2000w inverter/charger, with direct wire output to a load center. I've currently got circuits powering overhead LED lights, two 72" ceiling fans, and eight NEMA 5-15 120v outlets. Plan on adding an additional circuit for the dock.
I have three more 200w panels I need to mount to my barn roof, which will give me 1200w total PV and help maintain batteries during a run of overcast days; my panels being mounted sub-optimally (west-southwest vs. south) and subject to late afternoon shading reduce my generation potential.
A ceiling fan that uses a DC motor, such as those made by Fanimation and available at Lowes, use stupid low energy for the air they move. I have Slinger V2s and they move 6400CFM for only 14W of draw.
Depending on the pump you are planning to run and when/how long you plan to run it, could probably design a simple system with a single 200w panel, 20A MPPT charge controller, two 6V GC2 batteries (or a single DC31), and a 600w pure sine inverter. With solar, it is ALWAYS better to slightly oversize everything...
Full disclaimer that I'm no electrician, but it appears that a 500' run of 10/2 would keep voltage drop less than 4.2% with a 10A load.