This project, unlike most, was not approached with a fixed budget. Given the initial cost of the unique size (almost 9 acres) and location (City of Concord, but adjacent to a pond) of the raw land, as well as the anticipated costs of developing the site, we knew the added costs of going "zero net" would not drive the final costs as much as would be the case if this was a simple city or suburban type lot. Extra costs were also allocated for considerable outdoor living spaces as well as a second (detached) garage/barn outbuilding. Additionally, some of the non-energy related residential features/costs were specifically done to demonstrate that a ZNE home need not be small, boxlike or unattractive ......as some of the earlier (pre-2010) examples had been. Further, the secondary goals of an aging-in-place design with a multi-generational use capability also added to some of the project costs. Having said all that, our goal was still aimed at keeping the actual residential building costs (including all net costs of the renewable energy systems) to below $200/sf of conditioned space, which we did at $175/sf.
30% Investment Tax Credit on all qualifying energy technologies
Solar Hot Water Incentive- $1,900
Certified Energy Star Home Builder's Incentive - $4,500
Take advantage of whatever rebates or incentives are available at the the time of project development, as they may vary at any specific period of time of project development. Rebates and incentives are not the "drivers" of creating a ZNE project, they simply lower the entry cost. Use the cost of the electricity producing component (ex- PV panels) as the means to drive the HERS # from less than 30-35 (near net zero) ...... to 0 "net". Future utility rates may offer less than full retail off-set value for net metered power that flows into the grid when real time production exceeds use, which will lower some of the monetary value created through self generation and the financial benefits of achieving zero net status.
The total return on investment goes far beyond the annual electrical savings estimated at $3000/yr on a current cost basis, as there are no fuel costs associated with the annual operation of the home beyond the tiny amount of propane used for the stove cook top. The outdoor spa, which uses about 1500 kWh/year, is included in these numbers. The spa uses approximately 10% of the output of the PV panels on an annual basis. With a minimum life expectancy of 25 years for the electrical/mechanical technology installed, combined with the inflation related costs of fuels and grid provided electricity, an attractive ROI could still be represented if that was your only driving force for going zero net.
The installed cost of PV systems today (2016) are far more competitive as panel costs continue to decline and the number of installers increase. However, we feel we received a very competitive price (exclusive of battery store) for the time (2011) these were installed. The simple payback for this system is approximately 10 years. SRECs have not yet been sold for this project.
Additionally, as this was our first Geo-Solar Hybrid residential installation, we believe the cost of the same sized system now (2016) would be reduced by at least 1/3 through further simplification for residential applications as well as increased mechanical contractor competition and equipment pricing. The simple payback for the increased cost above a conventional propane fired heating and cooling HVAC system for this project is approximately 15 years, which would fall to about 10 years if costs were reduced by 1/3.