Hotels are one of the most interesting building applications for photovoltaic-thermal systems because they can have a substantial and relatively persistent demand for both hot water and electricity.
Unlike many residential buildings, a hotel may require domestic hot water throughout the day, while also consuming electricity for:
- lighting;
- ventilation;
- air conditioning;
- refrigeration;
- pumps;
- elevators;
- kitchens;
- laundry;
- guest-room loads.
This creates an important PVT opportunity:
The hotel may be able to use both outputs of a PVT collector—electricity and useful heat—within the same building.
But a hotel is not automatically a good PVT project.
The engineering question is whether the solar resource, DHW demand, heating/cooling demand, temperature requirements, storage and heat-pump architecture can be matched effectively.
The design approach in this article uses two Solis reference architectures:
- Solis Brine 450W — indirect-expansion reference design;
- Solis DX 450W — direct-expansion reference design.
1. Why Hotels Are a Distinct PVT Application
The defining characteristic of a hotel is not simply its size.
It is the combination of:
- variable occupancy;
- relatively high DHW demand;
- substantial electrical demand;
- heating/cooling requirements;
- kitchen and laundry loads;
- long operating hours.
A simplified hotel energy system can be represented as:
This creates several possible pathways for PVT energy.
2. The Hotel’s DHW Profile Is the First Major Design Variable
For many hotels, DHW is not a minor secondary load.
It can be associated with:
- guest showers;
- bathrooms;
- kitchens;
- laundry;
- restaurants;
- cleaning;
- other hot-water services.
The designer therefore needs a time-dependent DHW profile.
At minimum, determine:
- number of rooms;
- expected occupancy;
- daily hot-water demand;
- peak demand periods;
- required storage temperature;
- recovery period;
- other simultaneous DHW loads.
A useful design principle is:
Do not size the PVT array from the hotel’s annual DHW consumption alone.
The hourly and seasonal relationship between solar production and DHW demand matters.
3. Why Hotels Can Match PVT Particularly Well
Hotels can have thermal demand during periods when solar energy is available.
For example:
Later in the day:
This does not mean solar production and hotel demand will always coincide.
Instead, it means that hotel operation can provide useful opportunities for load matching and storage.