Re: Solar water heater for farm water trough?
A completely different tack. Heat line makes submersible semi-conductor heat tape in both 12 vdc and 120 ac configurations. Couple this to a agua-stat so that they draw no current until the water temp reaches a prescribe degree of cold,,say +.5C or 33F. A few watts of heat tape running only as needed might work just fine.
I have also installed a number of horse waterers with built in heat systems in them. They are self filling so they only hold ~ 1 gallon of water so the heat requirement to keep them above freezing is pretty small. The harder trick is keeping the water lines to them from freezing given how little water they use.
Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!