Quite simply solar without storge at an economical rate is not worth it yet. For those looking to save a few dollars , you can buy retrofit solar for water heaters that cost between $1700.00 to $2200.00 , they fit most existing water storage heaters and will keep them hot all day . Simple enough to install.
a couple of the retrofit systems can be found here
commodoreaustralia.com.au runonsun.com.au we are about to install one atleast to keep our hotwater ring hot during the day,we already turn our other heatpumps off from 9 to 10am till about 3 or 4pm and have noticed no great loss off heat in these units , which don`t take long to heat up once turned back on.