PVT Heat Pump System Design Example: Solis DX 450W Reference Architecture

1. DX PVT System Concept

A conventional air-source or ground-source heat pump uses an external evaporator.

A DX PVT heat pump replaces this heat source interface with the PVT collector.

Traditional Heat Pump:

Environmental Heat Source

↓

Evaporator

↓

Compressor

↓

Condenser

DX PVT Heat Pump:

PVT Collector

↓

Refrigerant Evaporation

↓

Compressor

↓

Condenser

The collector directly participates in the refrigeration cycle.

2. Solis DX 450W Reference Architecture

System Overview

                 Solar Radiation

                       ↓


              Solis DX 450W PVT

                       ↓


          Refrigerant Evaporation Section

                       ↓


                 Compressor

                       ↓


             Condenser / Heating Side

                       ↓


             Building Energy Demand

3. Main Engineering Layers

The DX 450W reference design consists of five engineering layers.

Layer 1: Solar Collection Layer

Function

Generate:

• electricity;
• thermal energy.

The thermal energy directly supports refrigerant evaporation.

Layer 2: Refrigeration Integration Layer

This is the key difference from Brine systems.

The collector becomes:

PVT Collector

=

Solar Absorber

+

Refrigerant Evaporator

The design must consider:

• refrigerant flow;
• evaporation stability;
• heat transfer efficiency.

Layer 3: Compression and Heat Upgrade Layer

The compressor increases refrigerant pressure and temperature.

Energy conversion:

Low Temperature Heat

↓

High Temperature Heating Output

Layer 4: Condensation Layer

The refrigerant releases heat to:

• space heating;
• domestic hot water;
• thermal storage.

Layer 5: Control Layer

The controller manages:

• operating conditions;
• protection;
• system response.

4. DX 450W Engineering Objectives

The DX architecture aims to achieve:

High Integration

Reducing intermediate heat transfer stages.

Reduced Thermal Losses

Removing the secondary fluid loop may reduce additional transfer losses.

Compact System Design

The collector and heat pump become a more integrated system.

5. DX Collector-Refrigerant Matching

The most important engineering relationship:

PVT Collector

↓

Refrigerant Evaporation

↓

Heat Pump Performance

The collector must provide suitable conditions for:

• refrigerant evaporation;
• stable heat absorption;
• compressor operation.

6. Refrigeration Circuit Design Considerations

6.1 Refrigerant Distribution

The collector field must support:

• appropriate refrigerant circulation;
• balanced evaporation.

Poor distribution may cause:

• uneven collector utilization;
• unstable operation.

6.2 Evaporation Temperature Management

The evaporation temperature affects:

• heat pump efficiency;
• heating capacity;
• operating stability.

The objective:

Maintain favorable evaporation conditions while extracting useful solar heat.

6.3 Refrigerant Charge Management

A DX system requires careful consideration of:

• refrigerant quantity;
• operating range;
• system safety.

7. DX 450W Control Strategy

Unlike Brine systems, DX systems cannot rely on hydraulic flow adjustment.

Control focuses on:

• refrigeration cycle management;
• operating protection;
• source condition response.

Solar Variation Response

Solar radiation changes continuously.

The system must respond to:

• collector temperature;
• evaporation conditions;
• heating demand.

Operating Logic Example

High Solar Availability

Higher Collector Energy

↓

Stable Evaporation

↓

Efficient Heat Pump Operation

Low Solar Availability

System evaluates:

• available heat source;
• operating limits;
• auxiliary requirements.

8. DX 450W Performance Evaluation

The evaluation boundary:

PVT Collector

+

Refrigeration Circuit

+

Heat Pump

+

Building Load

Important evaluation items:

Collector Side

• thermal contribution;
• operating temperature.

Refrigeration Side

• evaporation behavior;
• cycle stability.

System Side

• heating output;
• electricity consumption;
• seasonal operation.

9. DX 450W Verification Framework

Before application:

Collector Verification

Confirm:

• thermal characteristics;
• mechanical reliability.

Available collector testing evidence supports evaluation of collector-level thermal and durability-related characteristics.

Refrigeration Verification

Confirm:

• refrigerant compatibility;
• operating stability;
• system protection.

Heat Pump Verification

Confirm:

• capacity matching;
• operating range.

System Verification

Confirm:

• integrated operation;
• control strategy;
• expected energy flow.

10. DX 450W Compared With Brine 450W

11. DX vs Brine Selection Logic

Choose DX Architecture When:

Suitable conditions:

• compact integrated systems;
• dedicated heat pump design;
• direct collector integration requirements.

Choose Brine Architecture When:

Suitable conditions:

• flexible heat pump integration;
• separation between collector and heat pump;
• broader project adaptation.

12. Common DX Design Mistakes

Mistake 1: Treating DX PVT Like a Normal Solar Thermal Collector

The collector is part of the refrigeration cycle.

Mistake 2: Ignoring Refrigerant Distribution

Uneven evaporation affects system performance.

Mistake 3: Evaluating Only Collector Performance

DX performance depends on collector-refrigeration interaction.

Mistake 4: Ignoring Control Strategy

DX systems require coordinated operation between source and refrigeration cycle.

13. Solis DX 450W Engineering Position

The DX 450W reference architecture represents:

A Highly Integrated PVT Heat Pump Platform

Engineering advantages:

• direct heat transfer path;
• integrated collector design;
• compact system concept.

Engineering focus:

• refrigeration matching;
• evaporation control;
• system validation.