Techno-economic evaluation of PVT-sourced heat pump systems: can solar compete with air and ground in cold climates?

• Dynamic TRNSYS simulations of a Nordic multi-family building with PVT-sourced HP • Finned PVT reaches SPF4+≈2.5 and ∼15–20% auxiliary heater at 2.3–3.4 m²/kWₜₕ • Low-cost polymeric absorber achieves similar cost at full-roof coverage • Cost optimum at SPF4+≈2.2–2.3 — not at peak efficiency • Optimized PVT-only systems match ASHP cost, avoiding noise and borehole drilling There are various ways to integrate solar photovoltaic-thermal (PVT) collectors with heat pumps, but using the PVT array as the sole source offers unique advantages: eliminating noise from air-source units and avoiding the cost and land use of boreholes. This work investigates whether PVT collectors can operate as the sole source for a brine-water heat pump in cold-climate multi-family houses (MFH), and how absorber design and system sizing influence techno-economic performance. Five unglazed PVT absorbers with different design characteristics, are simulated in a validated TRNSYS model of a 2,000 m² Swedish MFH. Collector area is varied from 1.1 to 4.5 m²/kWₜₕ of nominal heat pump capacity, equivalent to a rooftop coverage of 25 to 100 %, while brine flow rate is varied from 24 to 96 l/h-m 2 . Finned designs achieve the highest seasonal performance factor (SPF) of 2.4 to 2.6 at moderate rooftop coverage (2.3-3.4 m²/kWₜₕ), with 15-20 % auxiliary heating share, while unfinned concepts converge at an SPF of approximately 2.2 and 25-35 % auxiliary heating share at full rooftop coverage (4.5 m²/kWₜₕ). Arrays below ∼2 m²/kWₜₕ are non-viable (SPF < 1.8; 40-70 % auxiliary heating). The economic optimum occurs at an SPF of around 2.2, not at the highest efficiency, yielding two optimal pathways: fin-enhanced absorbers at ∼2.3–3.4 m²/kWₜₕ, or low-cost polymeric absorbers at 4.5 m²/kWₜₕ. The best PVT-only configurations achieve cost parity with air source heat pumps (±5 %) and remain ∼10-15 % below district heating. They remain more expensive than GSHP systems, but avoid both outdoor noise and drilling requirements.