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Installers & partners

The Fronius Ohmpilot, a heating hero – part 1

Interesting facts

This article is aimed at anyone looking to take their customers’ photovoltaic systems to the next level by using photovoltaic current to heat water. The Fronius Ohmpilot will allow your customers to significantly increase their rate of self-consumption, whilst protecting their existing heating system. And that’s not all! Keep reading this article to discover 12 compelling reasons for integrating the Fronius Ohmpilot into every photovoltaic system. Plus, we will be providing you with further explanations in the coming weeks.
Fronius Ohmpilot

1. With the Fronius Ohmpilot, you can supply your customers’ homes with power and hot water using photovoltaics

The Fronius Ohmpilot is a consumption controller that uses PV current to heat water and towel radiators amongst other consumers. This makes it possible for your customers to give their primary heat source – e.g. oil heating – a break during the summer months.


2. The Fronius Ohmpilot makes the way your customers control the water heating elements in boilers and buffer tanks smart

With the Fronius Ohmpilot, heating elements can be continuously adjusted  between 0 and 9 kW provided that they have three phases: 3 kW of power are available for each phase.


Power range Phase 1 Phase 2 Phase 3
0 - 3 kW 0 - 3 kW adjustable - -
3 - 6 kW 0 - 3 kW adjustable 3 kW fixed  -
6 - 9 kW 0 - 3 kW adjustable 3 kW fixed 3 kW fixed


3. With the Fronius Ohmpilot, two heating elements can be controlled independently 

The Ohmpilot can be used, for example, to feed a 9kW heating element in a hot water tank in an infinitely variable manner. An additional 9kW load can be controlled using a relay output. This will ensure that your customers are using PV energy in the most efficient way and heating water with little excess energy.

Another possible application is shift storage in boilers.



The first heating element starts off by heating just the top third of the boiler and then heats the bottom two thirds at a later stage. This way, your customers will have hot water available immediately but only a little excess energy. This makes even more sense when combined with the minimum temperature setting (see Point 7) because then only a third of the boiler will be kept at temperature.


4. The Fronius Ohmpilot can be combined perfectly with a gas, oil or pellet heating system

The Fronius Ohmpilot can be combined with a modern heat pump and it is also the perfect addition to existing gas, oil and pellet heating systems.


For example:

Imagine that a pellet heating system has been used exclusively to heat water up until now (e.g. 610kg of pellets needed every year). If there is enough PV energy, the Ohmpilot ensures that water is heated using solar power. If there is insufficient PV surplus available, the Ohmpilot will activate the pellet heating system.

It is possible to achieve the following values once the Fronius Ohmpilot has been installed:

  • Saving of 380kg of pellets per year
  • Increases self-sufficiency in hot water production by 64% per year.
  • Increases PV self-consumption by 48% per year.
  • Saves operating hours and more than 180 on/off cycles -> protects the existing pellet heating system hugely and increases the service life.



5. The Fronius Ohmpilot is fully compatible with a heat pump

Heat pumps are often used in new builds in particular. Combining the Ohmpilot with a heat pump maximises self-consumption. The Ohmpilot guarantees quick control and consumption of low power, whilst the heat pump ensures maximum efficiency in PV use.

6. The Fronius Ohmpilot takes the strain off the existing heating system (oil, gas, heat pump, electric heating) and prolongs its service life by reducing the number of on/off and hot/cold cycles


Let’s imagine that one of your customers has been using an oil heating system for heating water and consuming around 300 litres of heating oil every year just to heat water. In the summer, the roof-mounted PV system will provide enough solar power to cover the full amount of hot water required.


The Fronius Ohmpilot has many benefits:

  • Potential for co-generation of electricity and heating.
  • Saving of 180 litres of heating oil p.a.
  • Increases level of self-sufficiency in hot water production by 60% p.a.
  • Increases self-consumption by + 48% p.a.
  • Saves operating hours and more than 180 on/off cycle’s p.a.
  • Extends the service life of the heater.
  • Triggers oil heating if no PV surplus is available.


7. The Fronius Ohmpilot offers flexibility when it comes to maintaining a minimum temperature 

This function ensures that the user-specified temperature is not undershot.



Imagine that one of your customers’ needs their water at 45°C for showering between 05:00 and 08:00 and 18:00 and 21:00 every day. A temperature of 30°C will do between 11:00 and 13:00 for washing up. If there is insufficient PV surplus available, either mains current or the existing heating system used for hot water will be reverted to automatically. Your customer does not have to change any settings manually and yet their water will always be at the correct temperature for them at the right times. Lower minimum temperatures mean that the Ohmpilot can retain more PV surplus in the hot water as the difference to the maximum temperature (e.g. 60°C) is greater.    


8. The Fronius Ohmpilot enables the temperature to be limited

Assuming that the heating element does not have an adjustable thermostat, the Fronius Ohmpilot can be used to limit the temperature. This feature comes in handy, for example, when the Ohmpilot is being used to heat a room in which the temperature is not measured directly by the heating system.    


9. The Fronius Ohmpilot is more flexible and efficient than solar heating and requires zero maintenance

The Ohmpilot is far superior to a solar heating system in terms of both purchase costs and ongoing maintenance. Whilst a solar heating system requires maintenance work at regular intervals (depending on the manufacturer), the Fronius Ohmpilot does not need any at all. Solar heating will only allow your customers to generate heat from PV energy but a photovoltaic system with the Ohmpilot will take care of both current and heat. On top of all that, solar heating requires a difference in temperature between the boiler and solar water to generate hot water at all. The Ohmpilot, however, can turn even the tiniest amount of excess energy into hot water.    


10. Fronius Ohmpilot can be used to control infrared heating, towel rails and electric heating systems

The Ohmpilot is primarily used to control hot water heating elements. However, it can also be used to generate heat – to bring your customers’ hand towels to a pleasant temperature on a towel rail, for example. There is also the option of combining the Ohmpilot with an electric or infrared heating system. Infrared panels being used as heating elements are found more and more often, particularly in passive houses. In such cases, the Ohmpilot is the ideal solution for heating water. You will be helping your customers to boost their self-consumption rate, which will have a positive impact on their overall energy costs.      


11. The Fronius Ohmpilot boosts the self-consumption rate

With electricity prices rising and feed-in tariffs dropping or non-existent, it makes sense for customers to consume as much of their PV production themselves as possible. The Fronius Ohmpilot boosts the self-consumption rate by 30% to as much as 60%, meaning that your customers require less power from the grid and can reduce their energy costs     


12. The Fronius Ohmpilot can be used in combination with zero feed-in

More and more power grid operators in various countries are demanding a feed-in limit for PV power. This does not affect Fronius solutions at all thanks to dynamic power reduction from 0–100%. The Ohmpilot can be used without restriction within this range, using the power to generate heat rather than restricting it.


Press the button to continue with "THE FRONIUS OHMPILOT, A HEATING HERO - PART 2":

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