Pairing geothermal technology and solar photovoltaics for net-zero energy homes

Abstract

Homeowners across the globe are continually seeking methods of improving energy efficiency for financial benefit and personal satisfaction. From small contributions such as swapping light bulbs to large capital investment initiatives like upgraded heating and cooling systems, homeowner decisions require accurate data and confidence in potential outcomes. This study models the path to net-zero energy for two separate heating, ventilation and air conditioning (HVAC) plus solar photovoltaic (PV) systems in residential buildings across 12 Unites States climate zones, and determines the optimal combination for each climate zone. An existing, traditional air-conditioning system with natural gas furnace is paired with a PV array. The net-zero results are compared to the same residence upgraded to a climate-customized geothermal heat pump HVAC system paired with a PV array. Results confidently favor the geothermal HVAC system + PV for climates with a significant heating demand in winter, and the baseline + PV system for cooling-dominant climates, exceeding $3,900 and $3,500 annual household savings, respectively. A major contribution is the introduction of a template that predicts the net-zero system option for climate zones outside the 12 studied. Patterns in local soil properties, sun intensity and financial incentives allow for net-zero system predictions nationwide. For example, all locations resulting in a baseline + PV net-zero system have strong sun intensity ratings. This research delivers climate-specific recommendations for the preferred net-zero HVAC + PV system through analysis of accurate energy performance and financial forecasting. Recommendations provide homeowners with valuable expectations on two HVAC + PV options along the path to a net-zero energy home.