A split system only has the collector panels on the roof. The tank is located where your current tank is.

A small electrical pump is necessary to pump the hot water down from the panels into the tank. However, the energy for the pump is offset in reduced heat losses, as the tank is more protected.

If the ideal location of the collector panels is far away from the location of the old hot water tank, a split system will result in better water usage. The reason is that the hot water is stored closer to where it is used. That means you do not have to wait for the hot water to reach your shower.

An added advantage is the in-built frost support. If the temperature falls below 5 degrees the pump automatically starts circulating the water. That brings warmer water back up to the panels so that the chances of it freezing are reduced.

The disadvantages, slightly more expensive to buy and install.