Demonstration of a Solar Thermal Heat Pump System

Solar Thermal Heat Pump to provide domestic hot water and chilled water for a hotel resort.

Chromasun, Inc


San Jose, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Result

The project was completed within budget in mid-2016 and successfully demonstrated the basic functionality of the technology in a live commercial setting. Operating the system and collecting the data helped the team to understand several important lessons regarding handling ammonia refrigerant charge, and adjusting to unexpected changes in site specific hot water demand profile. The project team is using remaining match funds provided by the Southern California Gas Company to operate the technology for two years, and to engage the hospitality industry with technology transfer activities.

The Issue

Thermal loads comprise approximately a third of total energy inputs for commercial buildings. The hotel and resort industry use a high proportion of total energy for guest showers, laundry, commercial kitchens, pools, air conditioning, and other thermal requirements. Improvements in efficiency have increased during recent decades, but have generally been small and slowly adopted. Challenges remain in achieving California policies regarding reduction of greenhouse gases, oxides of nitrogen, and other air pollutants, in part owing to the lack of significant long-term progress with boiler technologies.

Project Innovation

This project demonstrated an innovative system for heating domestic hot water and increasing chiller efficiency in the hospitality industry. The system showed the potential to reduce the amount of natural gas used by 50%, using the Solar Thermal Heat Pump (STHP) system. The system is composed of two components: (1) Energy Concept's absorption chiller the Helisorber and (2) Chromasun's solar thermal collector. By removing heat from the evaporator return line of the building's existing chilled water system, the STHP system can combine and concentrate this energy with either solar or natural gas to provide 100% of the building's domestic hot water load on a 24/7 basis and increase the chilled water efficiency.

Project Benefits

In this application, the technology has the potential to deliver up to 28,000 gallons of hot water per day. By supplementing boiler heat with a renewable energy source this technology offsets up to approximately 45,000 therms of natural gas normally required by the boiler system. In addition the technology can reduce up to approximately 152,000 kWh (kilowatt-hour) of electricity per year through increased chiller efficiency. At full capacity, the peak load saving potential is approximately 25 kW. Solar thermal heat pump applications make economic sense when buildings have high hot water demand such as in the hospitality industry.

Lower Costs


By offsetting existing boiler natural gas usage this project is estimated to save approximately $21,000 in natural gas costs and $11,000 in electricity costs annually.

Environmental & Public Health

Environmental Sustainability

By advancing the engineering and economic performance of solar thermal heat pumps, this project provides an alternative to conventional natural gas fired water heating that could reduce GHG emissions through displacement of natural gas. The project is reported to save approximately 325 metric tons of CO2 annually.

Key Project Members

Project Member

Scott Reed

Director of Busniess Development



Energy Concepts Company, LLC


Sunwater Solar


Contact the Team