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PVT vs PV vs Heat Pump — Why Real Buildings Need Hybrid Solar Systems, Not Single-Source Energy

Q: PV

Great where: Net-metering exists, roof space abundant, stable electricity price, low water heating demand Terrible where: DHW demand constant, net-metering gone, CAPEX to kWh revenue capped

Q: Heat Pump

Great when: Input water > 25°C, load moderate, cycles steady Falls apart when: Inlet < 15–18°C, rapid peak demand, daily start–stop cycles

Q: PVT

Great when: Any building needs heat, roof space scarce, irradiation high, backup costs painful It is the only one whose benefit increases with demand.

In every commercial energy project there is a moment when someone asks the same question:

"Should we install PV? Or a heat pump?"

It sounds like the right question. But it is fundamentally misguided.

Hotels, hospitals, residential complexes, worker camps, laundries, campuses—they do not consume electricity as their final purpose. They consume comfort, water temperature, sterilization, showers, pools, meals, staff facilities. The core output is heat.

When you treat a building as an electrical appliance, PV works.
When you treat it as a real environment, PV alone collapses.

This is why, in every serious project we design, the conversation eventually returns to one simple principle: Real buildings need hybrid solar systems. Not single-source solutions.

Section 1: PV — A Powerful Technology Misapplied to Heating

Photovoltaics are brilliant at what they do:

Convert light to electricity
Feed the grid or power equipment
Scale vertically with capital

But PV has two structural weaknesses:

No Thermal Output

Nothing usable for hot water without conversion

Temperature Kills Performance

Hotter = Lower efficiency

Efficiency Loss

+1°C above 25°C = −0.3~0.5% efficiency

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PV	cURL Too many subrequests. cURL Too many subrequests.	cURL Too many subrequests.
cURL Too many subrequests.	Makes heat Hates cold inlet temperature	Very sensitive to operating cycles
PVT	Improves PV electrical performance Generates hot water continuously	Stabilizes heat pump input

PVT is not "better." It is the missing piece.

The Real Economics

Let's be brutally honest about ROI:

PV

Great where: Net-metering exists, roof space abundant, stable electricity price, low water heating demand

Terrible where: DHW demand constant, net-metering gone, CAPEX to kWh revenue capped

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Great when: Input water > 25°C, load moderate, cycles steady

Falls apart when: Inlet < 15–18°C, rapid peak demand, daily start–stop cycles

PVT

Great when: Any building needs heat, roof space scarce, irradiation high, backup costs painful

It is the only one whose benefit increases with demand.

Real Hotel Case Study — 110 Rooms

Daily laundry + SPA. Heat pump installed two years prior. Energy bill acceptable in winter, catastrophic in summer.

They added PV to offset it. It helped… on paper.

Peak season reality:

PV running at 72–78°C surface
Heat pump cycling continuously at 2.3–2.7 COP
Guests taking 3800–4200 L DHW each morning

"Why are you heating from 20°C?"

A simple 40 m² hybrid PVT array:

Stabilized PV at 48–54°C surface
Preheated inlet water to 32–38°C
Reduced compressor cycles by 35–45%
Increased usable energy per m² by > 2×

No magic. Just alignment with reality.

Hybrid Solar Architecture — How Real Buildings Should Work

PVT → Buffer Tank → Heat Pump → Boiler

PVT provides base thermal recovery
Tank provides stability + stratification
Heat pump lifts to final temperature
Boiler covers the 2–8% emergencies

Everything is predictable. Nothing is stressed.
Energy stops being improvisation. It becomes routine.

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