Yes, off grid solar is legal in Texas. In fact, there are no state laws specifically regulating off grid solar systems. This means that as long as your system is designed and installed in accordance with the National Electrical Code (NEC), you should be able to go off grid without any problems. There are, however, some counties and cities in Texas that have their own regulations regarding off grid solar, so it's always best to check with your local authorities before making the switch.