Solar Hotwater for a Rental Property

[Matt Leonard]

I have a 4-unit property in Maine that I provide heat & hot water that are currently off of the oil fired boiler.  Looking at yearly summary, i spent 7k on oil last year.  It is cost prohibitive to install 3 new heating systems to separate them out and put it on the tenant (my first choice.)  I do have plenty of South facing roof space and I am thinking of installing solar hot water panels to preheat the water for DHW and the heating system.  Has anyone looked into or done this at any of their properties?