Arizona’s “hard” water can be tough on a solar water heater. The minerals in the water can cause a buildup of limescale in the system’s solar collector, distribution pipes and heat exchanger. That can hurt your system’s performance and even cause it to fail.
You can circulate a mild solution of vinegar and water through the collector every few years. But your best bet is to invest in a mechanical water softener, which will help prevent limescale buildup on all of your home’s appliances, pipes and faucets.