Commercial Office Building Case Study: 1,580 m2 Cooling with 60 kW Solar PV and an Air-to-Water Heat Pump
After commissioning on **10 June 2026**, the office cooling system imported only **214 kWh of grid electricity** during approximately **nine days of initial monitored operation**, while operating alongside a **60 kW rooftop PV system**.
>**Key measured result:** 214 kWh grid electricity imported by the cooling system during the initial monitored period, with 60 kW rooftop PV and a 210 kW air-to-water heat pump system installed on site.
This case study explains how the system was designed, installed, and monitored, using real project photos and operating records rather than theoretical savings claims.
Overview
This project is a 1,580 m2 office building in Kunshan, Jiangsu, China, equipped with a 210 kW commercial air-to-water heat pump system made up of [two 105 kW air-to-water heat pump units](https://nordthermglobal.com/products/r32-commercial-air-to-water-heat-pump-for-heating-cooling-and-hot-water) and a 60 kW rooftop photovoltaic system.
The system provides year-round space conditioning: chilled water for summer cooling and hot water for winter heating. It serves office fan coil units through a hydronic loop. This project is for space heating and cooling only, and does not include domestic hot water production.
*Figure 1. Completed rooftop heat pump plant with two commercial air-to-water units, insulated hydronic piping, circulation equipment, and water-side components.*
| Item | Detail |
|---|---|
| Application | Office building space heating and cooling |
| Conditioned area | 1,580 m2 |
| Rooftop solar array | 60 kW photovoltaic system |
| Heat pump system | 210 kW total nominal capacity, using 2 x 105 kW air-to-water heat pump units |
| Compressor system | Inverter compressor operation confirmed in monitoring data |
| Distribution | Chilled / hot water loop serving office fan coil units |
| Buffer / storage | Hydronic buffer and thermal storage for system stability |
| Location | Kunshan, Jiangsu, China |
| Commissioned | 10 June 2026 |
| Operating pattern | Daytime business hours, with limited demand on weekends and holidays |
Why office buildings suit solar-powered cooling
Office buildings are one of the most suitable applications for combining rooftop solar PV with commercial HVAC cooling.
The reason is simple: office cooling demand usually happens during the day, when solar generation is also available. As staff arrive and indoor cooling load rises, the rooftop PV array is already producing power. Around midday and early afternoon, both solar output and cooling demand are often high.
This load profile is very different from many residential buildings, where cooling demand may peak in the evening after solar output has dropped. For a daytime-operated office building, the overlap between cooling demand and PV generation can improve on-site solar utilization and reduce daytime grid dependence.
For office HVAC retrofit projects, solar-assisted HVAC systems can be especially relevant when the existing cooling load is already served by a hydronic fan coil system or when a building owner is considering an office chiller replacement.
Kunshan is located in China's hot-summer / cold-winter climate zone. The same reversible air-to-water heat pump can therefore provide cooling in summer and heating in winter, allowing one rooftop plant to serve the building throughout the year.
System design: solar-first, grid-supplemented
The system is designed around a solar-first operating concept.
During daytime operation, the 60 kW rooftop PV array supplies power to the building's cooling system. When solar generation is lower, such as in the early morning, late afternoon, cloudy conditions, or during higher load periods, the grid automatically supplies the remaining power required.
In short:
**Solar power is used first when available, while the grid provides automatic backup to maintain stable operation.**
There is no need for manual switching. The electrical supply arrangement allows the heat pump to continue operating smoothly even when solar output changes.
*Figure 2. System working principle: solar PV is used first, grid electricity provides automatic backup, and the air-to-water heat pump supplies chilled or hot water to the office fan coil units.*
*Figure 3. Rooftop 60 kW solar PV array installed on the same office building.*
Installation highlights
This was a commercial-scale rooftop installation, so equipment handling and rooftop coordination were important parts of the project.
Because both the PV array and the heat pump plant occupied the rooftop, the equipment layout had to consider maintenance access, piping routes, water tank position, and crane lifting space.
- **Crane lifting:** The air-to-water heat pump was lifted to the rooftop by crane.
- **Rooftop plant layout:** The heat pump, circulation pumps, hydronic buffer, expansion vessel, water tanks, and insulated piping were assembled as one rooftop plant.
- **Insulated chilled-water piping:** Pipework and headers were insulated to reduce thermal loss and help prevent condensation during cooling operation.
- **Compact rooftop integration:** The heat pump plant and PV array were both installed on the same building roof, making use of available rooftop space.
*Figure 4. Commercial air-to-water heat pump unit being lifted to the rooftop by crane.*
Live operating data
The project evidence comes from two layers. Real-time monitoring shows how the heat pump operates minute by minute, while the utility meter report shows how much electricity was actually imported from the grid during the initial operating period.
The heat pump system reports operating data to a monitoring backend. A representative snapshot from **17 June 2026 at 14:22** shows the system running in cooling mode at part load.
At that moment, the monitoring screen showed:
- **Chilled water temperature:** approximately 10 deg C leaving water and 11 deg C return water
- **Compressor operation:** the monitored compressor channels were running at about 34 Hz
- **PV input:** four MPPT channels producing about 14.9 kW combined at that instant
- MPPT 1: 4.63 kW
- MPPT 2: 2.79 kW
- MPPT 3: 4.59 kW
- MPPT 4: 2.85 kW
*Figure 5. Live monitoring interface showing compressor frequency, chilled-water temperatures, and instantaneous PV contribution from four MPPT inputs.*
This is an instantaneous operating snapshot, not a daily or monthly total. It should be read as evidence of real-time system operation: the compressors were modulating under part-load conditions, chilled water was being produced, and solar PV was contributing power at the same time.
The 14.9 kW PV reading should not be compared directly with the 60 kW array rating. It is a single moment in time, and PV output depends on irradiance, weather, time of day, module temperature, system status, and load conditions.
Grid energy report after commissioning
The utility meter report covers **1 June 2026 to 30 June 2026**. The heat pump system was commissioned on **10 June 2026**, and the relevant cooling operation in this record represents approximately **nine days of initial monitored operation**, not a full month of normal operation.
The report shows the cooling outdoor unit / office cooling system imported a total of **214 kWh from the grid** during that initial monitored operating period.
*Figure 6. June utility meter report showing grid electricity imported by the office cooling system after commissioning.*
| Tariff period | Share | Grid import |
|---|---:|---:|
| Sharp peak | 0% | 0 kWh |
| Peak | 64.86% | 138.8 kWh |
| Flat | 17.57% | 37.6 kWh |
| Valley | 17.57% | 37.6 kWh |
| **Total** | **100%** | **214 kWh** |
The key figure here is **grid import**, not total system energy consumption and not total cooling energy delivered.
Because the project also uses rooftop PV, part of the heat pump's electrical demand may be supplied directly by on-site solar generation during daytime operation. However, this dataset does not include the PV array's total generation over the same period. For that reason, this case study does not state a solar coverage percentage or a solar self-consumption rate.
What can be stated accurately is:
**During approximately nine days of initial monitored operation after commissioning, the system imported 214 kWh from the grid while operating with a 60 kW rooftop PV system available for daytime power supply.**
Recommended Nordtherm commercial heat pump options
For similar commercial buildings, the final product selection should be based on project capacity, local climate, required water temperature, refrigerant preference, noise limits, and installation conditions. Nordtherm can match the system design with different large-capacity commercial air-to-water heat pump options.
Use the product links below to adapt this case page to your website's product structure:
| Product type | Best-fit positioning | Product URL placeholder |
|---|---|---|
| 105 kW commercial air-to-water heat pump | Main unit size used in this case; suitable as the primary link in the overview and CTA | [105 kW commercial air-to-water heat pump]https://nordthermglobal.com/products/r290-commercial-air-to-water-heat-pump-50-100kw-high-temp|
| R32 commercial air-to-water heat pump | High-efficiency commercial heating and cooling projects where R32 is preferred | [R32 commercial air-to-water heat pump](https://nordthermglobal.com/products/r32-commercial-air-to-water-heat-pump-for-heating-cooling-and-hot-water) |
| R410A commercial air-to-water heat pump | Mature commercial solution for markets where R410A systems remain widely specified | [R410A commercial air-to-water heat pump](https://nordthermglobal.com/products/r410a-commercial-air-to-water-heat-pump-80kw-480kw-oem-solution) |
If your product catalog uses different refrigerant names or series names, keep the same structure and replace the anchor text with your actual product category names.
Why this project matters
This project shows how a daytime-operated office building can combine rooftop solar PV with inverter air-to-water heat pumps to form a practical commercial heating and cooling system with lower daytime grid dependence.
The value of the project is not only the equipment itself, but the match between three factors:
1. Daytime cooling demand
2. On-site rooftop solar generation
3. Inverter heat pump operation that can modulate with real building load
Together, these make the system especially suitable for commercial buildings whose main cooling load occurs during working hours.
That makes the approach a practical reference for similar office buildings, campuses, public buildings, and low carbon office HVAC projects.
Suitable applications
This design approach is most suitable for buildings with daytime heating or cooling demand, especially where rooftop space is available for PV installation.
Typical applications include:
- Office buildings
- Corporate headquarters
- Business parks
- Schools and campuses
- Government and public administration buildings
- Clinics and healthcare facilities
- Light-commercial buildings
Buildings with most of their cooling or heating demand after dark may still benefit from heat pump systems, but they may capture less direct value from on-site solar PV unless additional storage or load-shifting strategies are used.
Engineering takeaways
This Kunshan office building case demonstrates three practical design principles:
- Match daytime cooling demand with daytime solar generation.
- Use inverter air-to-water heat pumps instead of relying only on fixed-capacity equipment.
- Evaluate measured grid import instead of relying on theoretical energy-saving claims.
For commercial buildings with daytime cooling demand, rooftop solar PV and inverter air-to-water heat pumps can be a strong combination. This project provides a real example: solar-first operation, automatic grid supplement, monitored heat pump performance, and measured grid-import data from an actual office building in Kunshan.
Nordtherm can support EPC contractors, HVAC consultants, developers, and distributors with commercial heat pump selection, system design, and project configuration.
[Contact Nordtherm for commercial heat pump project support] sales@nordtherm.com
*Prepared as part of Nordtherm's engineering case study series. All figures are based on real installation photos, live system monitoring, and meter data provided for this project.*
