There are many reason why someone should consider installing a solar thermal system even though gas prices are currently low:
1) The amount paid for the system is equity in your house. If you should sell your home at some point in the future, and the system was maintained, you are likely to completely recover that equity (perhaps a little less or even a lot more.)
2) Increase your immunity to fluctuating energy costs. As energy costs inevitably fluctuate their impacts on your bottom line will be such smaller as you purchase less from utilities.
3) A major factor contributing to low natural gas prices is the non-conventional gas extraction method of hydraulic fracturing (fracking.) This has caused a large increase in the supply of natural gas and hence the lower prices. However the repercussions of fracking are slowly coming to light. In addition to causing earthquakes, and potentially contaminating water tables, fracking significantly contributes to greenhouse gas (GHG) emissions. Although natural gas releases less GHG emissions when burned as compared to coal and diesel, it has the highest GHG contributions if one considers the GHG emissions from extraction to consumption. These results were recently analyzed and published* based on considering a 20-year time frame for GHG equivalency since methane (a major contributor of global climate change and significantly released in fracking) has a 12 year lifetime.
4) Your helping the local economy and promoting green jobs.
5) If your solar thermal system is for a heated pool, you would effectively pay for the system over the next 4-8 years whether you get one or not. You can invest today and enjoy monthly savings and increase home equity, or you can pay the utility company every month.
6) Money saved from the system is effectively non-taxable income, depending on your tax bracket.
7) The planet’s ecosystem (including us) urgently requires humans to use solar technologies.
The list could go on…