Cost-benefit analysis of integrating BIPV-T air systems into energy-efficient homes

Abstract

The market share of building-integrated photovoltaics (BIPV) remains limited. One of the main barriers to its larger adoption is its initial capital cost, as BIPV is generally more expensive than traditional roof or façade mounted photovoltaic modules (PV). Converting BIPV systems into BIPV with thermal energy recovery (BIPV-T) can improve its benefit and competitiveness compared to other solar energy technologies. This benefit is difficult to estimate, however, as it strongly depends on the usefulness of the thermal energy produced and the incremental cost of the technology to recover the heat. This study aims at evaluating the cost-benefit of BIPV-T focusing on systems that use air as the heat recovery fluid and are integrated into all-electric energy-efficient homes located in heating dominated climates. This cost-benefit is evaluated using the concept of break-even cost defined as the maximum incremental cost to convert a BIPV system into a BIPV-T system to break-even with the cost of (a) a BIPV system and (b) side-by-side PV modules and solar thermal collectors (PV+T). To obtain this cost, the useful equivalent energy production of BIPV, BIPV-T and PV+T systems was first obtained for six energy-efficient housing archetypes located in various cities across Canada. Four different heat management scenarios were considered for the BIPV-T system: (1) fresh air preheating, (2) domestic hot water preheating through an air-to-water heat exchanger, (3) domestic hot water and space heating with an air-to-water heat pump and (4) domestic hot water heating (DHW) with a heat pump water heater. Compared to BIPV, BIPV-T systems always produce more useful energy and as a result, the break-even cost compared to a BIPV system was found to be always positive and up to 2700CAD for a medium 2-storey home located in Montreal. For that same house and considering the price of BIPV equal to that of standard roof-mounted PV modules, the break-even cost of a BIPVT system compared to a PV+T system was estimated at 4200CAD. If the price of BIPV were to get 10% lower than PV, however, this break-even cost could increase to 6400CAD.