All Case Studies
Project Brief
U.S. Virgin Islands
Thermal Energy HQ
Thermal Energy HQ Technical Team
November 18, 2025
Hospitality
Domestic hot water
Retrofit / System Replacement
PVT, Heat Pump, Thermal Storage, Domestic Hot Water
Bolongo Bay required a reliable domestic hot water upgrade for its beach resort operation in the U.S. Virgin Islands, where inadequate hot water had become a recurring guest complaint. The project replaced an aged and underperforming legacy DHW arrangement with an integrated Thermal Energy HQ solution that combined photovoltaic thermal (PVT), thermal storage, and heat pump support. The result was a fully operational system designed to improve hot water availability, reduce dependence on conventional grid-based water heating, and create capacity for future service expansion.
The resort’s legacy hot water infrastructure was no longer meeting operational needs. The existing setup included seven 100-gallon hot water tanks with immersive electric elements, while an earlier solar thermal system on the roof was already inoperative. The property used a recirculatory hot water system serving 45 rooms, with estimated usage around 350 gallons per day. In practice, the lack of dependable hot water had become the number one guest complaint, making system replacement a hospitality performance issue as much as an energy issue.
Thermal Energy HQ deployed a hybrid domestic hot water solution centered on rooftop PVT generation and thermal storage, supported by an Arctic heat pump configuration for baseline load coverage and backup operation. The installed system included 20 PVT panels paired with two 350-gallon thermal tanks on the rooftop, delivering 2.7 kW of peak electrical power and 12.7 kW of peak thermal power. An Arctic heat pump with two 35-gallon thermal tanks was installed on the sub-roof to support baseline demand and provide resilience. Combined annual system output was listed at 26,587 kWh, with enough excess capacity to support possible extension of hot water service to an additional wing of the resort.
This project highlights the importance of designing DHW systems around real operating conditions rather than only historical constraints. Once guests had access to sufficient hot water, monitored system data showed actual demand rose to 540 gallons per day, well above the earlier 350-gallon-per-day estimate. Because the system had been designed with adequate capacity, that increase did not create added operating cost pressure. For hospitality sites, this reinforces the need for monitored performance, resilient backup, and sufficient thermal storage when hot water reliability directly affects guest experience.
The completed Bolongo Bay installation delivered a fully operational domestic hot water system with improved service reliability and a clear financial case. The case study lists annual DHW energy cost at $8,040 under an energy cost of $0.53 per unit, with the upgraded system modeled to reduce that to zero for this application scenario. Total project cost was listed at $108,000, including system cost, labor, engineering and permitting, and shipping. With $48,000 in available incentives, the net project cost was reduced to $60,000. The resulting payback was shown at 7.1 years, with a simple ROI of 14 percent.
For hotels and resorts, domestic hot water failures quickly become a customer experience problem. This project shows how a properly sized combination of PVT, heat pump support, and thermal storage can replace outdated electric tank infrastructure, stabilize hot water delivery, and maintain performance even when real demand exceeds initial estimates.
