Performance analysis of a PV driven heat pump system during a heating season in high latitude countries

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1 Performance analysis of a PV driven heat pump system during a heating season in high latitude countries Bartosz Chwieduk, Dorota Chwieduk Institute of Heat Engineering, Faculty of Power and Aeronautical Engineering Warsaw University of Technology bartosz.chwieduk@itc.pw.edu.pl dorota.chwieduk@itc.pw.edu.pl

2 Since Polish nearly zero energy buildings single family houses - 70 kwh/(m 2 year) multifamily buildings - 65 kwh/(m 2 year). High energy consumption in building sector In Poland 70% of final energy consumption in buildings is used for the space heating Energy conservation in buildings is one of the strongest needs. Nowadays Old buildings are underintensive thermal modernization process. New buildings are designed, constructed and operated with stress on: thermal (insulation) quality efficient use and operation of energy systems. EU Directive on Energy Performance of Buildings Polish regulations- indices of primary energy consumption: single family houses kwh/(m 2 year) multifamily buildings - 105kWh/(m 2 year).

3 Reduction of the energy needs of a building can be achieved through: good architecture and building construction, application of appropriate materials. Reduction of energy consumption can be accomplished through: utilization of efficient energy systems and their devices, application of renewable energy technologies, including: solar energytechnologies, heat pumps based on renewables. Energy efficiency firstthen modern options of energy conservation Reduction of the energy needs through well designed architecture and building construction make the utilization of renewable energy systems more efficient and reliable 3

4 Poland warm summers, solar irradiation high. No needs for space heating. A solar thermal system can nearly cover the full DHW heating needs. Poland cold winters, solar irradiation low. High space heating needs Solar energy can be used as preliminary energy for heating another source of energy is needed - e.g. a ground heat pump. Energy production is based on fossil fuels in Poland To reduce fossil fuels consumption - utilization of renewables is recommended e.g. PV driven heat pump PV driven heat pumps are supported by the National Environmental Fund I Warszawa I Zamość I Kołobrzeg I II II IV V VI VII VIII IX X XI XII a ground source heat pump is not used in summer - natural heat recovery of the ground body.

5 Low energy house Due to the well planned architecture - solar house conceptthe monthly heat demand is small in winter, 4 months of the heating season only, Needs in March and October can be neglected. Total monthly heat losses due to the heat transfer through envelope and ventilation, and heat gains (internal and solar), and final heat demand Monthly components energy balance of Total heat losses (kwh) Total heat gains (kwh) Heat demand (kwh) January February March October ,8 November December The indices of primary energy consumption are very low. Annual primary energy consumption for heating - 25,58 kwh/(m 2 a)

6 Heating of the building via a ground source heat pump coupled with a solar heating system. The paralelmode of operation: at different time of a day or at the same time. A heat pump can supply heat: directly to the underfloor heating system or indirectly charging the storage tank, first. Solar collectors supply heat to the stoarge tank. 1 liquid solar collectors 5, auxiliary electrical heater 2 buffer storage tank 6 - heat pump 3 inner DHW storage tank 4 main DHW tank 7 - ground heat source for a heat pump 8 - space heated by underfloor heating system Main components of the system: solar collectors -10,92 m 2 aperture area main buffer storage tank liters, + DHW tank with electric heater 50 liters. ground source heat pump of thermal capacity - 8,1 kw four with vertical U shaped heat exchangers - each of 50 m depth

7 The print screen of a display of configuration and operation of the ground heat pump system coupled with solar heating system Implementation of renewable energy solar energy - to drive a heat pump to reduce consumption of the fossil fuel based electricity

8 Calculations of the electrical energy needs of all electrical appliances and the heat pump Electrical energy needs of all electrical appliances and a heat pump of the building in hours of the selected days of the year Validation of results of calculations against the real monthly electricity consumption by the real operation of all devices installed in the building.

9 Sizing of the PV system based on the best month and the worst month method: The installed capacity of the PV system should be: 2.7 kw and 61,5 kw, respectively. Due to: the space (surface area) available on the roof, the investment costs of the PV system. The first option - small size of the PV system kw is selected. 11 multi-crystalline silicon PV modules size of 1.640m x 0.99m with (total 17,9 m 2 ) the peak capacity W p. each. The total annual electrical energy gained by the selected PV system is equal to 2859 kwh.

10 Determination of the availability of solar radiation on inclined surfaces of PV modules: calculations of the hourly solar irradiations (inclination 30 0, orientation: to the south) for every hour of every day of the averaged year. isotropic diffuse solar radiation model hourly sums of direct and diffuse solar radiation from official meteorological national data set. Calculations of energy produced by the PV systems Solar gains of the selected PV system in the following: hours of the year days of the year

11 Space heating demand calculations Validated by the electricity consumption during heating season Daily electrical energy needed to drive a heat pump for space heating of the building Total energy required to drive a compressor of the heat pump during heating season 2185 kwh 30% of total electricity consumption in the building.

12 Compatibility of the heat pump operation supplying heat to the space heating system and PV system providing heat to drive the heat pump Two options of the PV system configuration and operation: PV system with batteries the heat pump uses 100% of energy gained by the PV system: from modules and batteries = 559 kwh, i.e. 25% of the total electricity needed to drive the heat pump PV with no batteries the heat pump operates when PV system operates, the heat pump uses 88,6% of energy gained by the PV system modules = 495,6 kwh,i.e. 23% of the total electrical energy needs of the heat pump. Type of PV system Without batteries With batteries PV modules 1830EUR 1830EUR Inverter 1370 EUR 1370 EUR - Batteries EUR - PV chargecontroller 230 EUR Installation 1370 EUR 1370 EUR Sum 4570 EUR EUR Investment costs of on-grid PV system and off-grid PV system

13 Compatibility of the heat pump operation supplying heat to the space heating system and PV system providing heat to drive the heat pump PV with no batteries The surplus of energy produced by the PV system is sent to the grid = 63.4 kwh The energy produced by the photovoltaic system during the heating season The energy from the grid used to drive the heat pump during the heating season The solar electric energy gained = 495,6 kwh or 559 kwh to drive a heat pump for space heating in the low energy building is not big. However, the reduction of 23-25% of energy supplied by fossil fuels is not small.

14 Indices of final and primary energy consumption for the all heating energy needs for three cases of the heating system of the low energy house Indices of annual energy Consumption Final (kwh/(m 2 a) Primary (kwh/(m 2 a) Ground heat pump coupled with a solar system Ground heat pump driven by PV system with batteries coupled with a solar system Ground heat pump driven by PV system without batteries coupled with a solar system Size and configuration of operation of the ground heat pump driven by PV system and coupled with the solar thermal system to supply heat in the low-energy house needs optimization. The optimization procedure should include the technical energy efficiency as well as the economic aspects.. from low energy house to energy positive house

15 Thank you for your attention