The basic heating system is a solar thermal system with flat-plate solar collectors (1), which are a source of heat for floor and wall heating of living unit and heating radiator of sanitary unit. Living unit is additionaly heated with an air solar collector (2), which is a part of the ventilation system of this unit. Living unit is also heated with 'solar radiator "(3), a mobile receiver in which the heat is stored in paraffin during phase change. Sanitary unit is also heated with the air vacuum solar collector (4). In addition the electricity, which is stored in batteries of PV system, could be used for heating water used in floor heating system.

The system consists of SONNENKRAFT IDMK flat-plate solar collectors that are modular and adapted for installation in roof of Cell's technological unit. Two sizes are used: IDMK12 with an area of 1.25 m² and IDMK25 with an area of ​2.52 m². The total solar collector area is 10.3 m². Two groups, each with three collectors, are connected in series. Optical efficiency of the SC is 0.79, the heat loss coefficient 4 W/m²K. The highest absorber temperature can be up to 180°C (at ambient temperature of 32°C and solar radiation of 1000 W/m²). The choice of thermal insulation of connecting pipelines was adapted to sustain this temperature.

Thermal energy storage tank (TES) SONNENKRAFT ProTrio 750 is made of stainless steel, it has a capacity of 750 litres and two coil heat exchangers. The first is connected with the solar collectors while the second is designed to heat sanitary water. Storage tank has thermal insulation shell made of three parts, making it easier to install in small spaces such as the technological unit of the Cell. Based on acceptable range of heating water temperatures in floor heating system, the tank can store up to 70 kWh of heat.

Hydraulic/protective unit SONNENKRAFT PSKR combines the circulation pump, filling and safety elements, temperature and pressure sensor and heat transfer fluid flow meter. The unit is connected to an electronic control unit SKSC2, in addition to managing the circulation pump and various regimes of system protection (max / min temperature, maximum temperature of SC, ...) allows the user a number of interesting features such as an overview of the produced heat, the number of systems operating hours or concurrent view of four temperatures in the system. Advanced users can modify the heat transfer fluid flow-rate, limit the maximum temperature of the collector or the uses the function of TES 'night cooling' on hot days.

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Trnovo, the place where Cell is set, is a part of Ljubljana that was known for its farms for growing vegetables and remains of Roman Emona. But this is not the only reason that we planted Phaseolus Aureus in front of solar collectors. Wide leaves of this plant shade the lower row of solar collectors and cool the air through evapotranspiration, thus reducing the risk of solar system overheating during the summer.

Sanitary and residential unit are heated with hot water heating system, which is connected to thermal energy storage of solar thermal system. In the sanitary unit a wire radiator is installed. A special feature is the radiator valve with electronic thermostatic head DANFOSS "eco living". Thermostatic head has a display through which the user can set the desired temperature in different parts of the day or week, functionality of "holiday" feature, which are tasks that ensure optimum thermal comfort at lower heat use. One of the features is also the automatic detection of an open window above the radiator.

Residential unit is heated with floating floor underfloor heating system TITAN UPONOR. The floating floor panel elements are placed on the floor and wall of the residential unit and are hydraulically separated in two circuits (loops). The tubes are made of PE-X (under high pressure molecularly cross-linked polyethylene) and are equipped with a layer of diffusion barrier, which prevents the diffusion of oxygen into the system. Pipes are hand-stamped in the grooves of aluminium double heat emission plates that are placed on a 25 mm thick pre-grooved polystyrene insulation panels. Emission plate improves the heat transfer from the pipe to the entire floor surface.

Thermal energy storage tank is connected with underfloor heating system with TITAN Uponor manifold. Manifold, which is installed in flush-mounted cabinet, is composed of energy-efficient circulation pump, thermostatic valve with capillary sensor that regulates the heating water temperature (20°C to 55°C), supply and return water manifold section, valves for hydraulically balancing of loops with flow meters and valves with the electro-thermal drive. Intelligent controls system Uponor DEM C-56 and I-76 with display are also located in the cabinet. Controller C-56 receipts radio signal from wireless room thermostat T-75 located in each room and regulates the desired temperature in the room through the electro-thermal driven valve. Controller regulates the circulation pump as well. Interface I-76 in conjunction with the controller allows the selection of the systems functions.

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Air solar collector has been developed specifically for the Cell. It is part of the ventilation system and enables also heat transfer from waste air that flows into the inner channel to the fresh air in the outer channel, which is covered with a transparent cover. The absorber has an area of 1 m² (400 x 2500 mm).

Residential unit is naturally heated with solar radiation transmitted through the window. Therefore glazing with high solar energy transmittance (g = 0.6) was selected. At solar noon the Cell could over-heat, due to small heat losses. This problem is being solved with the "solar radiator". This is a movable solar energy absorber, which provides internal window shading. Solar energy is than stored in the absorber with a micro-encapsulated phase change material. In our case, we used a panel of DuPont Energain with area of 1 m². At the end of the daytime we turn the solar radiator around so that it radiates heat in living space. In the solar radiator 300 Wh of heat is stored at 24°C. In an average winter day this is sufficient for six hours of residential unit heating. Also solar radiator was developed specially for the Cell.

Even this system was developed specially for the Cell. It consists of solar collector with six e vacuated tubes, which are connected in two parallel branches. The air enters the tube of vacuum collector directly from the technological unit and the warm air is blown in the sanitary unit. The total area of the solar collector is 0.73 m².

Cell can be heated with an electric heater which is integrated in solar heating system thermal energy storage. Based on the capacity of the batteries, it could be possible to maintain the temperature of 7°C in the Cell between one and two weeks.