PV-powered heat pumps with thermal, electrical storage


If combined with both thermal and electrical storage, PV-driven heat pumps in buildings could support higher self-consumption, according to a study by University of Catania scientists. The researchers have proposed a new energy system consisting of a PV array, an electric heat pump for space heating and cooling., and two different storage systems for heat (TES) and electricity (EES).

“We are preparing an extension of this research taking into account the opportunity of using photovoltaic-thermal (PVT) instead of PV solar collectors, in such a way as to satisfy a part of domestic heating and domestic hot water production,” Prof. Antonio Gaglianom told pv magazine.

The Italian group said that their proposed configuration significantly reduces the required battery capacity by 10 kWh or more, resulting in numerous financial and environmental advantages. They noted that surplus energy from the PV plant can be used for EES charging or activating the HP for TES charging.

The scientists conducted a simulation of the system through the TRNSYS software using a reference building in Catania. The system is assumed to rely on an electric heat pump with a thermal maximum power of 9.5 kW, a radiant floor system, and a 4.8 kW PV system using 300 W panels with an efficiency of 18.4%. Their modeling also considered solar radiation, wind speed, electrical load, electricity prices, and price- and incentive-based DR programs

“The total electricity demand is 10,828 kWh/year, which means 77.3 kWh/m2 (square meter of floor), while the electricity production from PV is 8,855 kWh/year,” they said, noting that around 34.1% of the generated solar power is self-consumed. “Therefore, due to lack of available space for the installation of the PV plant, the demand coverage factor is 81.8%.”

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They said that the system could achieve self-consumption and self-sufficiency rates of about 80% if linked to a thermal storage system and a 5 kWh electrical storage system. This high percentage is three times higher than that one achievable by an energy system without storage, according to the researchers.

“It allows for reduction of the emission of at least 1,300 kg CO2 equivalent, while the requested lower capacity of the electrical storage diminishes the installation costs, of about €10,000 ($10.700), which compensate for the extra costs for the installation of the thermal storage, of about €1,500.”

The scientists introduced the system in “Improvement of energy self-sufficiency in residential buildings by using solar-assisted heat pumps and thermal and electrical storage,” which was recently published in Sustainable Energy Technologies and Assessments.

“In the future works, the modeling of charging stations and parking lots of electric vehicles for charging and discharging and exchanging with the network will be discussed,” they said. “In addition, it is possible to examine the discussion of reliability in the network.”

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