Hot water with solar power

Many PV system owners wonder whether they can use their solar power even more efficiently. As an installer, you help your customers to optimize their PV systems and show them how they can save energy costs and become more independent by using intelligent solutions. We show you various ways of using surplus solar power to generate heat, thereby maximizing the use of self-generated electricity for yourself, using Fronius heating solutions.

If the water is heated with solar power, the system owners benefit in several ways: They increase the self-consumption rate of their PV system, reduce their energy costs, take the load off their heating system and take a big step towards independence from fossil fuels.

Basic water heating with Fronius inverter

The Fronius inverters have four integrated digital inputs and outputs, which allow them to be easily connected to third-party components such as a heat pump, pool pump or air conditioning system. Depending on the surplus PV or the PV production, these loads are then controlled and operated with solar energy. This enables plant owners to use their self-generated electricity even more efficiently and, for example, to generate hot water from their solar power with the help of a heat pump.

The advantages at a glance

Lower energy costs
Direct control of third-party components
Direct use of surplus PV for controlling a heat pump, for example
Integrated inverter function without additional costs

This is how the basic heating solution for hot water with solar power works

The digital inputs and outputs of the inverter allow loads to be controlled so that they are ideally operated with solar energy. Surplus energy thresholds are used to define the power at which the I/O is switched on or off. When the defined threshold is reached, the loads, such as a heat pump, are switched on. In addition to the surplus energy thresholds, you can also set a target running time or load prioritization to optimize the PV system’s self-consumption.

Intelligent water heating with the Fronius Ohmpilot

The Fronius Ohmpilot is the first choice for PV system owners who want to use their solar power to heat water. Thanks to the consumption regulator, the solar power can be used even more efficiently for heating hot water. Surplus solar energy which is otherwise fed into the public grid, goes, via the Fronius Ohmpilot, directly to loads such as a heating element, towel radiator or infrared heating. Even small surpluses are consumed with the heating element in a continuously variable manner and not fed into the grid.

The PV energy is thus used in the best possible way in the household and the self-consumption rate can be increased to up to 100 percent. This not only affects the return on investment of the PV system, but also the energy costs. In the summer months, the hot water consumption can be almost entirely covered by solar energy.ä The primary heating source usually remains completely switched off, which also increases the service life of the heating system.

The advantages at a glance

Extend the service life of the primary heat source
Hot water can largely be supplied by PV for 8 months of the year
Increase the self-consumption rate to up to 100%
Continuously adjustable regulation from 0 to 9 kW for optimum use of the surplus from the PV system
Lower energy costs
Can also be used in combination with zero feed-in
Short periods of bad weather can be bridged with ease

screenshot Solar.web Ohmpilot self consumption

Increased self-consumption with the Fronius Ohmpilot

The result with the Fronius Ohmpilot: the surplus power is not fed into the public grid. Instead, it is used by the water heating system by heating the water to a pre-set temperature. Self-consumption can be increased to up to 100% on the same day.

Energy fed into the grid
Fronius Ohmpilot power
Power consumed directly

This is how the heat solution works with the Fronius Ohmpilot

The Fronius Ohmpilot is a consumption regulator that uses the surplus energy from the PV system to heat water in the boiler. This means the water is heated with solar energy instead of conventional heating sources, such as an oil or pellet heating system. One of the key advantages of this solution is the continuously adjustable regulation from 0 to 9 kW, which enables the PV electricity to be used particularly efficiently. The Fronius Ohmpilot can also control other ohmic loads such as a towel radiator or infrared heating.

Full potential: Heating with Ohmpilot & heat pump

Both the basic solution with a heat pump and the Ohmpilot deliver many advantages. If you wish to use the full potential, simply combine the two solutions.
The basic heating solution can also be gradually expanded and optimised.

The advantage of a heat pump is its high efficiency – depending on the type of heat pump, it produces up to 5 parts heat from one part electricity.
The disadvantage of the heat pump is its inertia – numerous on and off cycles reduce its service life.

The load profile for a household with a heat pump clearly shows how often the heat pump turns on and off during the course of a day.

The Ohmpilot combined with a buffer storage tank comes into play here. This fast consumption regulator uses the surplus PV energy exactly to the watt and heats the hot water in the buffer storage tank via a heating element, for example. This means that the heat pump does not have to be active as often and therefore has a longer service life.

Another advantage of the Ohmpilot is that it can heat the buffer storage tank or boiler to a higher temperature than a heat pump, which is usually limited to approx. 55 °C. This means that it is even possible to get through periods of bad weather lasting several days without the heat pump having to switch on, which in turn leads to a longer service life.

Reference Eberstalzell - PV roof-top instllation - Fronius Solar Energy

Ohmpilot simulation in Fronius Solar.web

A simulation in the Fronius Solar.web online portal shows your customers the advantages Fronius Ohmpilot has to offer using individual, real data. In just a few minutes, you can see how much the Fronius Ohmpilot increases the self-consumption and how much the system owner saves each year.

To Solar.web

The Fronius Ohmpilot in action

The existing oil-powered heating system for the six-person household can now be deactivated for the entirety of the summer, thus reducing its usage and extending its service life. This has also lead to reduced fuel costs - a saving of over 430 litres of oil every year.Stein

Read the reference

Fronius Ohmpilot: How it’s used in real life

In our webinar, we will show you how to best use the Fronius Ohmpilot. especially for heating water. Practical examples will also be used to show you the many ways in which the Fronius Ohmpilot can be used with other heat sources and ohmic loads.

Watch the video

Man with headset sitting in front of laptop

Fronius Ohmpilot	Technical data
Frequency (input)	50 Hz
Max. output power	3 kW / 9 kW (each continuously adjustable)
Type of power regulation	Pulse width modulation
Dimensions (height x width x depth)	350 x 280 x 110 mm
Weight	3.9 kg

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Solar Energy

Fronius Heating Solutions