Common House Solar Hot Water Heating system

collectors in context

The Common House has a Solar Hot Water system that augments the natural gas powered hot water heater. The system was manufactured and installed by Backwards to the Future Ltd., in September 2005, during a state of Michigan program that offered a cash rebate on such installations. The system provides an environmentally friendly energy option and reduces our carbon footprint.

The system as installed cost $6540 for two sets of collectors and the state of Michigan rebate of $1400 per collector saved us a total of $2800. We estimated that the system would produce energy equivalent to 144 ccF of natural gas annually, which would make a payback period of approximately 26 years if the price of natural stayed at around $1 per ccF. Of course, the emissions and carbon offset savings would be substantial but were not part of the calculatd payback since there is no standard market for that yet in the US or Michigan.

The installation was financed by a number of households as "investors" in the system who would be paid back as the system produced energy -- at the same rate as was paid to DTE. Once the system was paid off, the community would own it outright.

More images of the installation including the installation process and instrumentation. The original proposal to the community has lots of detail.

The system works best on dry, bright days, with late January producing the best heat gain so far! A member investor notes the readings on the meter monthly, and updates the spreadsheet below and bills the Common House for energy produced! Annual reports are posted to the News page.

Notes

Spreadsheet showing measured use and cost recovery to date
The column called "Dividend per share in $" shows how many dollars per dollar of investment one can recoup thus far. (see the full spreadsheet here)