Hi there
If you are lucky enough to live where there is a Natural Gas supply pipeline available to your property or you can obtain Bottled LPG I would suggest that an economical way to heat water is by having installed an instantaneous gas water heater fitted to an outside wall. The most common brands are Rinnai, Bosch and Rheem – all of which can provide an endless supply of hot water provoiding there is gas and power available to them, they do not store hot water therefor you are not paying to heat and store water, they supply hot water once a tap is turned on and will continue to supply until a tap is turned off. As water is only heated as and when required the operating costs of these units is very good (unless you have teenagers who want to “live” in the shower).
Another but more expensive option would be to consider a sola heater water heater system for which there are many brands available.
Contact one of your Local Plumber/Gasfitters and ask them to give you a quotation so you have something to consider
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians