Sustainable Cities and Buildings

KNX city KNX city

Sustainable cities and buildings

With the number of people living in world’s population lives in towns and cent of all greenhouse gas emissions. urban areas increasing, supplies of raw cities. By 2050 this figure will have risen This in turns requires transdisciplinary materials diminishing, and temperatures to as much as 70 per cent. So it is in solutions, in which not only the buil- rising worldwide, cities are set to face cities that the battle on climate change ding, but also mobility, energy-genera- some major challenges over the next and pollution will be won or lost. The ting equipment and infrastructure, are few years. Cities are responsible for most important challenge will there- equally taken into account. KNX city two-thirds of global energy consumpti- fore be to make urban development shows how such holistic solutions can on, 60 per cent of total water consump- sustainable. This requires sustainable be incorporated into sustainable cities, tion, and 70 per cent of greenhouse gas buildings, because buildings current- and how they interact with the building. emissions. And they continue to grow. ly account for more than 40 per cent Already, more than 50 per cent of the of global energy use, and hence 21 per

BUILDINGS

What will the building Cities can only be sustainable if the in- KNX city solution of the future look like? dividual buildings are energy-efficient. The building’s energy management sys- KNX already offers solutions today The building of the future will be tem will be monitored quantitatively by for smart metering, electric vehicles, energy-efficient and capable of smart meters. Based on this information improving energy efficiency, power communicating with its environ- steps can then be taken to improve the generation management, load/tariff ment (the smart grid). energy efficiency not just of the building management, and communication itself, but also of the entire district, or between buildings. even the city as a whole.

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Mobility

How will we get from Mobility is becoming more and more im- KNX city solution A to B in the future? portant, and in future a large percentage of all vehicles will run on electricity. But KNX offers solutions already to- In vehicles powered by renewable electric vehicles are only worthwhile if day for using e.g. the surplus energy energy. their batteries are charged exclusively from on-site photovoltaic systems with renewable electricity. Solutions or smaller scale wind turbines on therefore need to be found for charging buildings to charge electric vehicles electric vehicles with renewable power 100 per cent with renewable energy. from either on-site generating systems or the local power grid.

Infrastructure

Infrastructure is becoming more and How will energy use KNX city solution be managed in cities more important. Already today it is clear in the future? that no one solution will be capable of KNX already offers solutions today overcoming all of the challenges facing our that use communication technology Energy will be managed at a multi- energy supply. These challenges are the and IP/internet to link up buildings building level, taking account any result of the increasing use of renewable on separate sites as though they decentralised power generation energy in general, and decentralised pow- were a single building. systems. er generation in particular. Many different disciplines will need to work together to create a single overall solution from nu- merous individual solutions.

Power Generation

The world is on the cusp of a major shift How will we produce KNX city solution energy in the future? in the way it produces and uses energy. As energy is obtained increasingly from KNX already offers load manage- Mainly renewably, in other words unpredictable renewable sources, the ment solutions today that address from sun and wind. great challenge will be to keep energy the problem of fluctuating power supplies reliable. Many utility companies supplies from photovoltaic systems will in future manage loads indirectly by and wind turbines. charging tariffs variable in time, in order to motivate customers to switch power consumers on or off at particular times of day.

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KNX city – the sustainable city What form will communication take in cities in the future?

Information and communication technology (ICT) will be an essential element of smart grids and infrastructure in the future. ICT is a vital component of the holistic solution needed to create a sustainable city. KNX will provide all of the interfaces needed between the city of the future and smart grid communications infrastructures, itself becoming an integral part of the smart grid. Because it brings together buildings, transport, energy generation and infrastructure in a holistic way, KNX can already offer innovative solutions today for making cities more sustainable while exploiting the potential of transdisciplinary approaches.

Buildings Energy-efficient buildings are the cornerstone of sustainable cities

Advantages Energy-efficient buildings are at the but also switch them on or off. KNX Energy savings heart of any sustainable city. KNX of- touch panels enable the control of vari- • KNX shading control: 40% saving fers a wide range of solutions for impro- ous household appliances to switch them • KNX individual room control: ving the energy efficiency of all kinds of on or off electronically. This represents 50% energy saving buildings, from private homes to large a major benefit over other systems, as • KNX lighting control: 60% saving company premises. These include load of course simply turning the power on • KNX ventilation control: 60% saving management concepts, which always or off is not sufficient to properly start involve sensors and actuators. The sen- up or shut down a typical domestic ap- sors gather information, for example pliance. KNX also offers a wide range of consumption figures, or information on interfaces for intelligent connections bet- the status of a given component, while ween a KNX system and a heat pump. the actuators respond to this informati- Wall-mounted home charging points for on by triggering an action. Actions can electric vehicles can also be integrated include making or breaking an electric into KNX networks via actuators, enab- circuit, turning on or off a device such ling the charging process to be started or as a heat pump or a household appliance, stopped from a KNX touch panel. If the or switching on or off more conventi- building has its own micro power plant, onal power consumers. KNX energy for example a photovoltaic system, any actuators are particularly useful devices KNX connected charging points can be here, because they not only measure the configured to charge the vehicle using power consumption of electric circuits, only electricity produced on-site.

Mobility With KNX, electric cars are an integral part of intelligent buildings

Advantages For a city’s electricity supply, electric ve- night for longer than it takes to charge • Electric cars can be integrated into hicles mean an increase in power con- their batteries. In principle it should KNX intelligent building control systems sumption. Not only that, but electric therefore be possible, instead of char- • KNX makes charging electric cars cars are likely to use the most electricity ging them in the evening, to charge them more eco-friendly in the evening, as drivers return home at night or even in the very early hours • KNX can control the discharge of electric from work and plug their vehicles in to of the morning. This would help consi- car batteries according to the amount of be charged overnight. This happens at a derably to spread the load more evenly power needed by the smart building time when private households use the over a 24-hour period. Where different most electricity anyway, so the additi- electricity tariffs apply at different times onal demand from electric vehicles will of day, it can even make sense to stop pose a threat to the city’s reliability of or start the charging process at specific supply. This is because nearby trans- times so that charging takes place when formers could become overloaded, but electricity is cheaper, or to make maxi- also because the excess demand calls for mum use of the power generated by an additional generating capacities. Electric on-site photovoltaic system. vehicles are likely to stand unused over-

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Infrastructure KNX links up different houses and buildings with one another

Advantages KNX infrastructure solutions allow seve- tricity. The KNX infrastructure solution • KNX can network buildings with one ral buildings within a city to be networked is of course also suitable for controlling all another with one another as though they were traditional KNX applications. The sustai- • KNX can be used to manage con- just one building. In the sustainable city nable city of tomorrow needs a seamless sumption of the future this can be very beneficial, flow of communication from the power • KNX incorporates smart grids into for example for building operators or grid to the city, on into the building or intelligent building control systems housing associations responsible for seve- household, and back to the grid. In the ral different buildings or sites. If a building sustainable city of the future KNX will be operator has already a micro power plant responsible for communication at building (e.g. photovoltaic system) on one site and level and will also provide all necessary in- would like to build a car park for electric terfaces to the smart grid to facilitate tariff vehicles at a second site, this KNX soluti- management, power generation manage- on can be used to ensure that the vehicles ment, load management and, where re- are only charged if the power plant at the levant, storage management throughout. other location is generating enough elec-

Power Generation Renewable energy is an integral part of any KNX-controlled smart building

Advantages Renewable energy is constantly gaining in of electrical energy. However, it is hardly • KNX reduces fossil fuel consumption popularity compared to traditional ener- realistic to store electricity on the kind of • KNX increases the use of energy from gy sources. But renewable energy sour- scale necessary. In future, power genera- on-site power plants ces fluctuate, producing electricity only tion management and load management • KNX coordinates the use of renewable when, for example, the sun is shining or will therefore be essential. KNX offers energy resources between different the wind is blowing. This poses challenges load management solutions that permit smart buildings for electricity grids. If, for example, on a the adaptation of conventional electric sunny day electricity is fed into the local loads and electric loads from HVAC sys- grid from photovoltaic systems in quanti- tems, white goods and electric vehicles ties far exceeding the load on the grid (i.e. according to the amount of renewable the demand for electricity) at that time, energy generated by the building, or in re- this can cause voltage problems. The sponse to a electricity tariff fluctuating in other way around, if there is a demand- time (determined by the amount of rene- supply gap because demand is high at a wable energy produced in that section of time when renewable power generation the grid), without any loss of comfort or is missing or collapsing, this gap must be convenience. All solutions available so far filled by electricity from conventional po- have had one thing in common: that they wer stations that need to be started up can interact with each other within the at short notice. One potential solution building, but not with the outside world. that is frequently discussed is the storage KNX will change all that.

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Smart metering KNX smart metering is at the core of KNX city

Energy transparency throughout the building Smart Metering ‘Energy management’ can be defined in different ways depending on the per- spective (i.e. when viewed in relation Gas to the building or the city as a whole). Control and Visualisation In buildings, energy management helps both to save useful energy such as elec- Heat tricity and heat, and to reduce consumption of gas and water. The first step in energy management is for building users to take a more conscious Water approach on how they use resources. Those who have access to clear infor- Home-Loads mation on current rates of consump- Electric tion will use energy and water more Power carefully. At present the standard technology for obtaining this information is the smart electricity, heat and water E-Mobility HVAC meters provided by suppliers. The nu- merous KNX smart metering compo- or Power nents available give users greater transparency over their consumption and Grid spending. A wide range of KNX meters and actuators with current detection is KNX offers sensors and actuators for every possible application. The picture shows a typical topology for also available, for use in application- a KNX installation in a main distribution board, including electricity meters for e.g. general consumption, HVAC applications or electric vehicles, and power generation. specific smart metering solutions.

Optimising consumption Visualising energy consumption data alone is not enough to actively improve KNX measurement white goods a building‘s efficiency. Ideally, in additi- up to 16 A on to consumption data, information on the weather, on indoor temperatures, on whether windows and doors are open or closed, on whether people are present, on room use, and other KNX measurement KNX measurement lighting up to 16 A relevant data should also be available. up to 80 A Only with detailed information can in- House connection terpretations be made about the buil- triphase ding users’ consumption behaviour and potential for reducing consumption. If this information is available it can then KNX measurement and circuit be used to optimise consumption, eit- KNX actuator sockets her manually or automatically. KNX so- steers power contactor up to 16 A lutions can gather energy data and then either visualise them, or trigger automa- ted processes in response to them. This is active energy management. It gives KNX measurement users constant access to consumption up to 80 A data and triggers automatic processes to improve a building‘s energy efficien- CEE plug triphase cy. Power connector up to 40 A

Smart electricity metering

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Smart grid Interaction between KNX and a smart grid

KNX city highlights innovative solutions that will in future make it possible to use renewable energy with no loss of comfort or convenience and no price increases. For this to be possible, the KNX solution must encompass not just individual buildings, but also the local and city-wide power grids and their energy management systems. In KNX city, KNX communicates with the smart grid. Four scenarios from the daily life of a city of the future are presented below. Potential problems are explained, and details are provided on how KNX responds to each scenario.

Scenario A: Surplus of renewable energy It is night-time: the load on the city’s grid of the surplus via communication tech- VA has dropped to its lowest level, but be- nology. They can then switch on KNX- 110 kV cause of strong winds large quantities of connected consumers such as white renewable energy are being fed into the goods and electric vehicles. In this way 20 kV grid. The city must somehow absorb this KNX is able to again balance the city’s excess electricity. All intelligent houses energy supply. 400 V and apartments are therefore informed

Scenario A

Scenario B: Insufficient renewable energy VA This situation can be seen as the reverse which it does with the help of KNX. 110 kV of scenario A. KNX city shows how, for KNX turns off electric vehicle charging example, the amount of power fed into points and white goods, and switches 20 kV the grid from wind turbines can drop in the air conditioning system or heat pump the morning time (due to low winds). over to ‘eco’ mode. In this way KNX is 400 V The city needs to react to this situati- able to prevent blackouts by again balan- on by reducing the load on the network, cing demand and supply.

Scenario B

Scenario C: Peak load across the entire city 20 kV The load on the grid is at its highest vices. Even with renewable energy fed in the evening because that is the time into the grid, electricity bottlenecks can when the city’s residents cook their occur at these times. Like in scenario B, Overload dinner, use more light, and switch on here KNX is able to reduce the energy 400 V TVs, stereos and white goods, causing demand of KNX connected consumers. a load peak. This situation is worsened Energy stored in the batteries of electric by increased energy use by the service vehicles can even be fed back into the industry and commuter transport ser- grid if necessary.

Scenario C

Scenario D: Local increase in voltage Photovoltaic systems feed energy direct- as this allows the load to be increased lo- 20 kV ly into the low-voltage grid. Particularly cally. This is done by switching on KNX around lunchtime, this can cause the sup- integrated consumers (e.g. white goods ply of renewable energy to exceed de- and electric vehicles) or increasing the 400 V mand, which can result in voltages rising load drawn by them (e.g. by switching to unacceptable levels. The problem can air-conditioning systems or heat pumps be solved if smart homes and apartments over to ‘comfort’ mode). are connected to a smart energy supply,

Overvoltage Scenario D

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KNX city – the solutions

Building

Example I: Demand Side Management Ethernet / KNX IP White goods Weiße Ware The challenge powerlinepowerline gateway gateway Traditionally, the amount of electricity produced by a power grid is adapted KNX TP KNX load to the actual energy demand. Different management: An algorithm stored in kinds of power plants – base load, me- a KNX PLC ensures dium load and peak load power plants that loads and domestic – operate at different times depending appliances are switched on the load, to ensure that the right on and off in harmony Power with the building’s on-site amount of electricity is always gene- Electric Grid photovoltaic system and, rated. Fluctuating renewable energy where relevant, electricity sources, on the other hand, have the storage capacities, with disadvantage that they cannot produce simultaneous submeter- on demand: if more power is sudden- ing via KNX energy actuators. ly needed, it is not possible to simply start generating electricity. With renewable energy, the traditional model of demand-based control does not work. The solution Practical implementation This can cause problems in terms of To adjust loads effectively, sensors Sensors: Overall metering is ensured reliability of supply, particularly if more are needed that can measure both the by Smart electricity meters (electronic renewable energy sources are used amount of electricity consumed, and domestic supply meters). In addition to and at the same time conventional fos- any power generated by a photovol- these, KNX DIN-rail meters collect con- sil fuel power stations are closed down. taic system. This can be done by either sumption data from individual sources. One possible solution that is currently KNX DIN-rail meters or KNX integra- discussed is the ‘smart grid’, which uses ted smart household meters. In addition Acturators: Conventional loads are con- information and communication tech- to the sensors, actuators are needed trolled by switching actuators. Energy ac- nology to vary electrical loads as ener- to connect and disconnect loads, e.g. tuators (from e.g. ABB or Siemens) are gy production fluctuates. The challenge switch domestic appliances on and off. a convenient solution, because they not is to create a KNX load management For standard loads, KNX switching only switch loads on and off but also mea- system that can vary the building’s elec- actuators can be used, while for more sure, thus combining sensor and actuator trical loads according to the amount of sophisticated loads such as white goods functionality in a single unit. Household electricity generated on-site, or in res- and HVAC systems, special KNX inter- appliances are connected by Powerline to ponse to changes in energy prices over faces need to be used to switch these a KNX panel (from e.g. BJE). Air conditio- the course of the day. devices on electronically. ning units are connected to KNX via the appropriate KNX interfaces.

Functions KNX measurementmeasurement white white goods goods • Adaptation of loads to amount of up toto 16 16 A A electricity generated on-site • Adaptation of loads according to electricity price

Advantages • Household appliances can be connect- KNX measurementmeasurement KNX measurementmeasurement Lighting Lighting up toto 80 80 A A up toto 16 16 A A ed to KNX via their Powerline interface. This is a far more elegant solution HouseHouse connectio connectionn triphasetriphase than simply cutting their power supply. • Saves money by taking advantage of the lowest tariffs KNX measurement and circuit • High degree of automation KNX measurement and circuit socketsSockets up toto 16 16 A A

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KNX RF interface with the KNX bus and continuously Example II: Here a KNX RF interface sends the data communicates the data to the KNX bus. Tariff based management directly to the KNX bus. The KNX RF signal can be converted to KNX TP using KNX RF The challenge a media coupler. Here a Hager KNX RF interface is con- In future, the conventional electricity Direct KNX meter nected directly to the smart electricity meters used by energy suppliers will This smart meter features a direct KNX meter and sends the measurements be replaced by smart meters. This is TP interface wirelessly to the KNX bus. Using the essential for calculating the amount Hager Domovea unit, the data can then chargeable to customers with varia- Practical implementation be visualised on any other KNX panel. blel electricity tariffs (which vary ac- Two possible solutions are presented In addition the metering values can be cording to the amount of renewable below: used by KNX actuators for controlling energy produced in a given section of electrical loads. the grid), because meters will need to KNX wired sensor measure not only the total amount Functions A wired sensor is mounted on the opti- of energy used and produced in ki- • Informs the KNX system of the cal customer interface of the electricity lowatt-hours, but also the amount of amount of power currently produced utility meter (magnetic contact). The energy consumed and produced (e.g. (PV) and the current electrical load sensor is connected via a KNX device by a photovoltaic system) every se- • Sends energy generation and con- cond. These smart meters also have sumption data to KNX a customer interface. To benefit from • Visualisation a KNX load management system it is necessary to input the tariffs in KNX. Advantages • Data from meters can be sent wirelessly or via cable The solution • No additional measuring sensors A variety of options are available for in- needed, as for conventional electrici- tegrating smart meters into KNX: ty meters • Allows automatic adjustment of elec- KNX wired sensor trical loads by KNX The meter is connected to KNX via its • Advantageous for power grids as lar- optical customer interface. ge amounts of electricity fed into the grid from PV systems does not increase the voltage in the grid: the additional power generated is absorbed Smart household meters for photovoltaics and re- by load increases motivated by lower lated systems, including KNX submetering electricity prices.

Data acquisitionacquisition and and transmission transmission DataData processing processing andand ar archivingchiving Data visualizationvisualisation toto thethe KNXKNX bus bus byby the the KNX KNX bus by EthernetEthernet

Function available late

Data acquisitionacquisition and and transmission transmission Data acquisitionacquisition and and transmission transmission DataData acquisition and and transmission transmission toto the KNXKNX bus bus toto the KNXKNX bus bus toto the KNXKNX bus bus

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Mobility

The challenge Interaction For many years, growing internati- Infrastructure with Building onal demand for oil coupled with a and Mobility finite supply of petroleum resources has been driving oil prices higher and higher. The private transport sector Starting is pinning its hopes on electric vehic- charging power les as a way of managing the world’s Tariff price signal dependence on oil. But for a city’s electricity supply, electric vehicles mean an increase in power consumption. Not only that, but electric cars are likely to use the most electrici- mits the information to the vehicle. The apply, the charging process can be acti- ty in the evening, as drivers return switching actuator needs to connect the vated and deactivated depending on the home from work and plug their ve- operating voltage of the pilot box in dif- current price. The charging process can hicles in to charge overnight. This ferent combinations with the four pre- also be started immediately from a KNX coincides with the time when private defined inputs of the pilot box. Two of panel, for example if the driver needs his households generally use the most them are used to control the charging car again imminently. electricity, so the additional demand power (S3, S4). The charging current poses a threat to reliability of supply. can be set to 6 A, 10 A, 16 A or 32 A. Advantages Even just a small number of electric vehic- Functions les being charged from the grid is enough A KNX integrated charging post gives to cause a local transformer overload. the building control system control over But if the charging post is integrated into The solution one of the largest and most energy-in- a smart home or apartment that receives Electric vehicles are likely to stand un- tensive loads in the home. If electricity is information from the smart grid when used for around 10 hours overnight – in short supply, the charge contactor can a transformer is close to overload, this considerably longer than the 3-5 hours be opened to reduce the load or, if this can be prevented by quickly stopping the it takes to charge their batteries. In is supported by the vehicle and the char- charging process. In the same way KNX principle it would be possible, instead of ging post, energy can even be fed back can also take advantage of a surplus of po- charging them in the evening, to char- into the grid. If variable electricity tariffs wer in the grid by resuming charging. ge them at night, for example in the very early morning hours, which would take considerable pressure off the grid. Where different electricity tariffs apply at different times of day, it can additi- onally make sense to stop or start the charging process at specific times so that charging takes place when electricity is cheaper.

Practical implementation For the connection of eCars to KNX, a pilot box can be used. With this device KNX telegrams can be indirectly sent to the eCar. With the telegrams, the eCar can start or stop the charging, or can vary the charging power. A KNX switching actuator controls the pilot box. Depending on the signals, the pilot box changes the PWM signal and trans-

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Infrastructure

Example I: Buildings on separate sites

The challenge KNX has solutions already available today that use communication technology and the internet to link up buildings on separate sites as though they were a single building. This is particularly relevant for housing associations that need to manage seve- Central visualisation for several individual sites ral buildings at once, or companies with buildings at locations scattered across a city. Advantages Functions This solution brings consumption and Solution/ Incorporating several buildings into a feed-in data together at a central point practical implementation single KNX installation makes it easier for accounting purposes. It also makes it KNX IP routers are used to connect to gather measurements for accounting possible for a single energy management each building’s KNX TP line with an IP and billing purposes. It also permits the system – for example a system for tur- network. If the KNX IP router is part of visualisation of all KNX functions at one ning down the heating or air conditioning a network with internet access, a secu- or more central locations. in offices at weekends – to span several re VPN tunnel connection can be esta- sites. A range of systems and sites can blished over the internet between that be visualised, managed and monitored building and other buildings with KNX remotely via an existing network or over IP routers. the internet (VPN connection).

Example II: Heating, AC and ventilation systems

The challenge To keep energy supply and demand in equilibrium even when the load on the grid is at its highest, cities need electrical loads that can be temporarily reduced or disconnected. Because space heating and air conditioning are responsible for a large percentage of urban energy use, only a slight change of the set point temperature can make a big difference to the amount of power available in the grid as a whole.

The solution Heat pumps and air conditioning sys- mitted via a gateway (e.g. Theben or tems are normally controlled according Zennio) to the heat pump or air con- to a set point set by the user. Room ditioning unit. thermostats compare the current tem- the comfort of those people living or perature with the thermostat setting Function working in the building. (setpoint) and turn the heat pump or The room air conditioners can be tur- air conditioning unit up or down in or- ned up or down depending on the cur- Advantages der to reach it. If the heat pump or air rent load on the grid. If the load is very Integrating a heat pump or air conditio- conditioning unit is connected to the high, for example, the setpoint for the ning system into KNX allows buildings KNX bus, the setpoint can be adjusted heating or air conditioning can be swit- to adapt their electrical loads to exter- automatically. ched to ‘eco’. This immediately reduces nal signals, for example a signal indica- the amount of energy needed by the ting the load on the grid or the current Practical implementation heat pump or air conditioning system. electricity price. As both the share of Users can store a range of temperature The other way around, when the load is renewable energy and electricity con- setpoints in a KNX panel, for example small or there is a surplus of power on sumption in general increase (due to ‘comfort temperature’, ‘standard tem- the grid, the setpoint can be switched electric vehicles), this kind of reactions perature’ and ‘eco temperature’. The to ‘comfort temperature’. This increa- will be crucial for maintaining a steady preferred setpoint can then be trans- ses the load on the grid and improves power supply.

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eNERGY Generation

Example: Monitoring and maintaining photovoltaic systems Home-Generation The challenge Photovoltaic systems are generally made up of several parallel rows – or ‘strings’ – of modules. In the worst case scenario, this means a faulty mo- dule can put the entire string out of White Goods operation. Unless the system is re- gularly monitored, faults of this kind can go unnoticed for a very long time. This KNX solution can monitor PV systems both with and without solar HVAC tracking, and record all relevant data.

The solution Many PV inverters even measure the Home-Loads AC current generated internally in the inverter. The standard models available on the market use RS232/RS485 ports for this purpose. KNX technology can directly access these ports and send the measured data to the KNX bus. This E-Mobility allows users to see where dirt has accu- mulated that could reduce the efficiency of the system, as often happens particularly in the case of flat modules. Tariff Grid Practical implementation The photovoltaic interface (e.g. Synapsi) gathers the measured values that are then transmitted to KNX. The other way around, measured data from KNX are also sent to the photovoltaic system. KNX weather stations and pyra- nometers are particularly important, because the measurements from these devices can be used in remote maintenance for checking that a given string is e.g. not faulty, but merely in the shade. KNX temperature sensors measure the • Comparative analysis of current pow- mits. Another problem is that energy temperature of the modules, to notify er generation and installed capacity suppliers and operators of distribution users of any instances of overheating due • KNX manages all technical and con- networks cannot know how much po- to faults, and hence prevent fires by pro- sumption data gathered for use in sub- wer is being fed in by what systems at viding early warning. If a fault does occur, sequent maintenance/servicing work any given moment. KNX can help here alarm signals are sent by UMTS to the by permitting the management of seve- remote maintenance point and KNX. Advantages ral photovoltaic systems together. Ar- In future a portion of the electricity in med with information about these sys- Functions grids will be fed in from local photovol- tems, electricity suppliers and network • Real-time monitoring of the function of taic systems. This will create challen- operators can then apply load manage- all components in photovoltaic systems ges for electricity grids. Particularly in ment and tariff management strategies • Data are collected at regular intervals low-voltage networks , large amounts to encourage end customers to adapt • KNX manages log files from several of power fed into the grid can cause their electric loads to the amount of different systems voltages to exceed the acceptable li- power currently being produced.

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