I would like to have a warmer TC floor... any ideas?

Chet, I got it!

I've been keeping up on this as time goes on, and I did see the electric ribbon solution. This is similar.

This is very low cost, and very low-wattage draw, so it can run off inverter and your solar should be able to keep up. They rate it at 12watts draw per SqFt.
Just add a thermostat and you're set.... You wouldn't even have to hardwire it, you could simply add a plug at the end of your wiring and plug it in.


110v heated floor mat