Energy management systems: when it makes sense to invest

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An energy management system (EMS) allows you to use more of your self-generated power for your own needs. You save on energy costs and achieve greater independence from fluctuating electricity prices with this technology, which optimally controls energy flows in the home. Read on to find out how it works and when it makes sense to install such a system.

Consume self-generated power in your home

Energy management systems are a technical solution for controlling energy flows. Used together with photovoltaic systems and power storage units, they enable self-generated power to be primarily consumed within the home.

This is not as complicated as it may initially sound and can be easily understood using this practical example: when the sun shines, your photovoltaic system converts the incident radiation energy into electricity. If you do not need this at that time, it may be used to charge a storage unit or can be fed into the public grid in return for payment. If you have used up all of your self-generated supply and the output from your photovoltaic system is low, you then have to buy back electrical energy from the grid at a high tariff.

Energy management systems match supply and demand

Energy management systems prevent this situation arising by better matching supply and demand. For this, an EMS monitors all energy flows in the home. It collects data on power generation as well as power consumption and uses the insights gained to control energy flows and appliances in the best possible way.  

Supported by weather forecasts, it is possible to start up flexible consumers according to demand. This means: If the photovoltaic system delivers a lot of electricity, the energy management system starts, for example, heating devices or the charging station for the e-car in order to consume electricity. If the supply and yield are currently scarce, the control system can reduce consumption in order to save electricity. In both cases, you will be supplied with your own solar power for longer and require less energy from the public grid.

Your preferences take precedence

However, the energy management system does not only pay attention to the PV system and its yields. It also takes into account predefined rules. This ensures that the electric car is charged even when the sun is not shining. The extent to which you adapt yourself and your behaviour to the solar yield is completely up to you.

Higher self-consumption with the same output and storage capacity

The level of self-consumption of a solar power system is a measure of how much self-generated energy is used within the home. Without an EMS and storage unit, the figure is 10 to 20  percent –– the system feeds 80 to 90  percent of the solar power into the public grid in return for payment. If you install a storage unit with an energy management system alongside the photovoltaic system, the level of self-consumption increases to 60 to 80  percent. You hardly need any electricity from the public grid and enjoy greater independence from rising electricity prices.

Energy management systems operate based on configuration and usage

The effect of an energy management system in private households depends strongly on the system configuration. It is particularly favourable when PV power and storage are optimally matched and flexible consumers are connected. The latter include heat pumps or e-car charging stations that can be switched on and off as needed. Without electricity storage, flexible consumers or both, the results can be improved with the solution, but you will not achieve the best values.

Transparency through smartphone, tablet and computer apps

Where is the electricity coming from right now? Where is it flowing to and how full is the power storage unit in your home? Applications such as the ViCare app provide the answers to these questions. You can keep track of all your energy flows via your smartphone or tablet – even remotely. The app serves as a user interface to the energy management system and ensures maximum transparency. A trade partner can quickly and easily install the energy management system. In addition to compatible devices, you will also need smart meters and an internet connection.

Advantages of energy management systems  

Energy management systems in homes increase the level of on-site consumption of self-generated solar power. They ensure less electricity is drawn from the public grid and help to reduce energy costs. With an EMS in your home, you gain greater independence from fluctuating electricity prices and can reliably plan ahead. At the same time, you are doing your bit for the energy transition. After all, the higher the level of self-consumption, the lower the load on the public grid and the fewer CO₂ emissions caused by consuming utility power. In addition, you are better protected against power failure – the more efficiently an EMS distributes electricity within the home, the longer you will have power if the grid is down.

The key advantages:

Increased self-consumption
Less power drawn from the grid
Greater independence
Energy cost savings
Electricity cost stabilisation
Conservation of fossil resources
Less burden on the public grid
Reduced CO₂ emissions

A worthwhile investment for many PV users

It makes sense to install an energy management system if you want to consume a lot of solar power in your home. In particular, systems with a storage unit achieve excellent self-consumption levels. But an EMS may still be worthwhile even without a storage unit, for example if you have a non-subsidised photovoltaic system for which the feed-in tariff is low or may be discontinued entirely in the future.  

Is an EMS also worthwhile for heat pumps without a PV system? Our expert clarifies

Yes, even homeowners who only have a heat pump can benefit from an energy management system. Marc Franken, Product Manager in the E-Systems division at Viessmann, explains how and why: "In order to be optimally prepared for the future, it also makes sense to activate an EMS for heat pumps without a PV system. You may not have any self-generated electricity that the heat pump can process in the best possible way, but you can benefit from dynamic electricity tariffs in the near future.  

This means that you can then switch on the heat pump via the energy management system and heat the buffer or domestic hot water tank when the electricity is particularly cheap. If the comfortable climate in the building allows it, or if the storage tanks have been charged beforehand, the heat pump can remain switched off when electricity is particularly expensive.

Data protection: energy management systems and privacy

Providers and users of energy management systems need to be mindful of security and data protection. This is true at least when data is transmitted between the EMS and the cloud, such as when you want to access your system from elsewhere. High security standards are then a must.  Generally speaking, there is nothing to worry about if you bear the following in mind and are careful with your data.  

  • Providers should be GDPR compliant and store all data on servers in the EU.  
  • They should check their IT systems regularly and react quickly to inconsistencies.  
  • Users are responsible for setting secure passwords.  
  • They should regularly check and maintain the technology in their home and install updates as soon as they are available.  

Your privacy is in safe hands with Viessmann. Our servers are located exclusively in the EU and we treat stored data with strict confidentiality. You can find more information about this on our ViCare FAQ page.

EMS support in the form of a tax incentive or BAFA grant

When you retrofit a modern solution for self-consumption optimisation, you are eligible for a subsidy for the energy management system. Grants of 15 to 20  percent are available and can be applied for through the Federal Office for Economic Affairs and Export Control (BAFA) before the delivery and service contracts are awarded. If you meet the technical requirements and have already started the modernisation work, you can use the tax incentive on offer. This can be claimed retrospectively via your income tax return for owner-occupied homes that are at least ten years old. For up to a maximum of €200,000 of your renovation costs, you can deduct 20  percent from your taxes, spread over a period of three years.  

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