For many improvements (e.g. kitchen, bath), you can capture a significant fraction of the value back when you sell your home. For solar PV, you can get it all back:
This premium sales price was slightly higher than the installation cost, the study determined: “These average sales price premiums appear to be comparable to the investment that homeowners have made to install PV systems in California, which from 2001 through 2009 averaged approximately $5 per DC watt… homeowners with PV also benefit from electricity cost savings after PV system installation and prior to home sale.” [emphasis added]
As the article goes on to illustrate, the homeowner also receives the free electricity from the PV system.
Go solar: it’s one heck of a money back guarantee!