Your home's hot water system is one of the more vital systems; your house isn't considered habitable unless you have hot water. You may have thought your current hot water system was working well, but as the system gets older, it can slowly fade in efficiency and function. It might be time to get a new hot water system. This can be a simple replacement with like fixtures, or it can be a major change.
Different hot water systems offer differing levels of efficiency. A solar-powered system uses renewable energy and reduces your electric bills; a traditional electric system does not leak like a gas-powered system might, reducing both your bills and the possibility of leaks. Finding a different type of heating system to provide hot water can make you more comfortable, and a plumber can show you what options might work in your home. Note that if you do anything to your hot water system other than replacing the fixtures with the same types, you'll have to renovate part of the house (e.g., to add solar panels, convert gas lines to electrical connections, and so on).
Sometimes you don't want another type of system because the one you have is working well for you, but what you have is currently old. If your hot water system is nearing a couple of decades in age, it's time to get a new system installed. You'll have more efficient appliances just due to how new the system is, and you may find your utility bills drop substantially even though you haven't changed the type of system.
A Major Change
Finally, maybe you want a really big change, going from a tank-storage system to a tankless system or vice versa. If you don't want the heat loss and extra energy use that comes with tank-storage systems, a tankless system would be a good change. If you prefer not to deal with an overwhelmed tankless system in a huge house, changing your hot water system to a tank-storage system may be the right move. This really is a big change, so before deciding to do this, speak with a plumber about what's involved in the conversion and how each system really affects water and utility bills along with the hot-water supply. You have to be sure you're making the right decision, so take your time with this one.
A hot water service can walk you through all the options you have for the change you want to make. Keep energy efficiency in mind, along with monthly bill costs, but also remember that you have to be comfortable using the system, and the system has to provide adequate hot water. A plumber will help you figure out which system is the one that's best for your home.