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Combined HEat SyStem by using Solar Energy and heaT pUmPs

Periodic Reporting for period 2 - CHESS-SETUP (Combined HEat SyStem by using Solar Energy and heaT pUmPs)

Reporting period: 2017-12-01 to 2020-09-30

The building sector accounts indicatively for 40% of the energy consumption and 36% of GHG in the EU. More specifically, energy consumption intended for heating and cooling represents around half the total of the final energy consumption. In EU households, heating and hot water alone account for 79% of the total final energy use (Heating and cooling: EU, 2020). Most of the thermal energy is produced from fossil fuels (66%), and only 13% comes from renewable energy (Heat Roadmap Europe, 2015). Also, it should be taken into consideration that over 35% of buildings in the EU are more than 50 years old, and around 75% of the EU’s building stock is considered inefficient (EU Buildings Database, 2020).

The CHESS SETUP project objective is to design, implement and promote a reliable, efficient and profitable system able to supply heating and hot water mainly from renewable sources to both new and existing buildings. The system is grounded in the optimal combination of solar energy production, heat storage and the use of a heat pump in a single system managed by an intelligent monitoring and control system.

The system operation is based on the use of solar panels (thermal, hybrid and photovoltaic) to transform solar radiation into heat and electricity, to be used for domestic hot water and heating. During the summer, there is high solar radiation and low heat demand. The unused share of the collected thermal energy is transferred to the seasonal storage tank to be stored, increasing the temperature of the storage medium—either liquid or solid. When the solar radiation is lower and the heat demand increases, a heat pump transfers the heat stored in the seasonal thermal storage at high efficiencies in order to satisfy the energy demand of the building. Part of the electricity produced by the solar panels is self-consumed by the system. If there is an electrical surplus, it can be stored in batteries or injected into the grid.

The operation is optimised according to some external factors, such as energy prices (electricity and gas), weather conditions or user requirements by using a smart control management system specifically developed for the project. This control system is customisable and easily adaptable as needed.

The combination of the high inertia of the seasonal storage system with the intelligent management system allows the energy to be supplied more efficiently and continuously, increasing the self-sufficiency of the system and reducing the peak demands.

The system not only provides a solution in terms of energy efficiency and primary energy consumption but, if implemented widely, could also have great benefits to the electrical grid by flattening the electric curve and allowing greater integration of renewable sources. This could be achieved through the control system, which can activate the heat pump during periods of low electricity demand, for example, or when the grid is not able to absorb the energy produced by renewable sources.
CHESS SETUP was installed in 3 different pilot sites with different climate conditions, sizing the elements according to the buildings’ characteristics such as the solar irradiation, energy demands, and available surface for the installation of solar panels and the thermal storage tank.

CORBY (England):
With cold weather and lower solar radiation, the system was implemented in 26 new dwellings, including 4 typologies of homes. The components of the technical solution proposed for new Corby dwellings are photovoltaic and hybrid solar panels, individual heat storage based in the ground by implementing an EEB in the form of shallow boreholes, a ground source heat pump, and batteries. There is no backup system.

MANLLEU (Spain):
The pilot was implemented in Lavola’s headquarters (existing office building). The components of the technical solution are photovoltaic panels, air source heat pump, and the benefits from the building’s thermal mass. The initial configuration of the building contained a natural gas boiler and a chiller unit (both kept as a backup system).

SANT CUGAT DEL VALLÈS (Spain):
The system was implemented in an existing sports centre with more than 6,000 users. The CHESS SETUP system was implemented in a building renovation at large scale. It is used for heating the water of the swimming pools, being the system very suitable for the energy demand profile throughout the year. The components of the technical solution are hybrid solar panels, 100 m3 heat storage water tank and a water source heat pump. The initial configuration of the sports centre used natural gas boilers that were maintained as a backup system.

Besides the testing of the system in 3 pilot cases, a simulation software to analyse the feasibility of the propose solution and to foresee the results before any implementation was developed, as well as an intelligent monitoring and control system. The potential of alternative working fluids for new heat pumps was also studied.

Heat Pump developments have shown that alternative working fluids for high temperature applications can be beneficial in terms of both performance (indirect environmental impact) and GHG (direct emissions) reduction. The performance of R134a compressors as high temperature units will be improved as new dedicated units appear.

All results are published and open access available at the website of the project and at Zenodo repository.
The combination of a solar energy collection system (hybrid and/or photovoltaic panels) coupled with the use of a high-efficient heat pump increase the efficiency of the heating system, reducing the demand of primary energy (mainly natural gas) and also reducing GHG emissions of the heating system.

If STES (water tank or geothermal boreholes) is added, supposes the opportunity to decouple electrical consumption from thermal demand, therefore resulting in an important improvement in the self-sufficiency and efficiency of the system. This allows to reduce or displace peak demands in the electric grid.

In terms of the business model, its standardisation and exploitation, CHESS SETUP was designed as an economical solution, requiring low investments that could be exploitable at different scales. Being a centralised system, it also reduces maintenance costs and energy losses. From the pilot experiences, we would like to highlight two interesting key exploitable results ready to be implemented by any interested stakeholder:

• CHESS SETUP system as a technical solution
• CHESS SETUP system as a global integrated solution based on energy services. The solution proposes a standardisation tool as well as a business model analysis for the case studies where energy service companies can play a role

These exploitable results show that CHESS SETUP is a suitable technical and environmental solution, as well as economically viable. Strategic alliances with manufacturers, suppliers, engineering companies and interested parties could open the range of opportunities to replicate the CHESS SETUP model, reducing costs and scaling the implementation of the system.
Lavola’s rooftop photovoltaic installation.
CHESS SETUP graphical interface of the system control and monitoring tool synoptic
CHESS SETUP team at Sant Cugat's sport centre rooftop (15th October 2019)
Conceptual schematic of CHESS SETUP system
Sant Cugat’s heat energy storage based in a water tank
Corby’s heat energy storage in the form of shallow boreholes