I need to replace a really old electric solar water heater in a
domestic hot water system, and I'll buy a conventional electric heater
because solar tanks cost much more but are of inferior quality.

Conventional heaters are usually modified for solar use by shortening
the dip tube in half and using it as the inlet for the solar-heated
water, and the drain opening replaces the normal dip tube for cold
water But I found this diagram:

www.solardev.com/images/ho****er_r2_c1.gif

which shows an unmodified conventional tank being used for solar
heating.
Instead of feeding the solar-heated water into the middle of the tank,
in this diagram it goes into the bottom. Will that work well?