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Contributing to grid stability the smart way – with the easyE4 from Eaton
Location: Andernach, Rhineland-Palatinate, Germany
Challenge: Adding ripple control to PV inverters in an easy and cost-effective manner
Solution: easyE4 control relay with Modbus RTU module
Result: Intelligent implementation of ripple control in accordance with the grid operator's specifications
We use Modbus RTU and the four potential-free switching contacts of the easyE4, which are connected to the grid operator’s ripple control receiver, to reduce the output to 60 %, 30 % or 0 %.
Background
It all began with a passion for electric cars – and purely electric ones at that. In order to advance the energy transition, Denis Röthke and Michael Giesa, founders and CEOs of IVG Energy Solutions GmbH, wanted to enable customers to power their electric vehicles using only electricity from renewable sources.
Recently established, the company specializes in holistic solutions in the field of photovoltaics (PV), from solar panels to inverters and storage systems. As the existing offer of PV systems, most of which had a payback period of 20 years, left much to be desired, the two decided to enter the wholesale market themselves in 2020.
After an intensive search, they finally came across a supplier whose products offered everything they were looking for – in terms of function, quality and price. These hybrid inverters not only convert direct current to alternating current, but are also specially designed to work with batteries to store surplus energy.
The only drawback is that in Germany, as in many other European countries, solar installations above a certain output must be equipped with a so-called ripple control receiver. Depending on the load on the grid and the amount of energy being fed in, this function enables grid operators to reduce the system output from 100% to 0% in four stages to prevent overloading. However, the inverters produced by IVG Energy Solution’s chosen manufacturer are not equipped with this function or the necessary connections.
Challenge
For use in Germany, the devices therefore have to be upgraded with ripple control hardware and software, which is mandatory for systems with a peak output of 30 kW or more. This threshold, also known as kilowatt peak (kWp), can be even lower in areas where grid capacity is particularly low.
In addition to selling the inverters, IVG Energy Solutions also wanted to differentiate itself from the competition by providing comprehensive pre-sales services and after-sales support, including smart connections to the Home Assistant and ioBroker building automation platforms.
However, the single-board computers originally used for this purpose quickly reached their limits, also in terms of reliability. Giesa and Röthke were therefore looking for a better solution to integrate ripple control receivers in the solar inverters. And the local Eaton representative, who happened to be in the building, had the right solution at hand: the easyE4 control relay, which is equivalent to a small programmable logic controller (PLC) due to its wide range of functions and communication modules.
Solution
The easyE4 with Modbus RTU module made it easy to implement the ripple control technology required by the German grid operators. “We use Modbus RTU and the four potential-free switching contacts of the easyE4, which are connected to the grid operator’s ripple control receiver, to reduce the output to 60 %, 30 % or 0 %,” says Denis Röthke.
But the easyE4 can do much more than that. As it is a fully-fledged controller instead of a circuit board, all the inverter’s information can be accessed. IVG Energy Solutions is thus currently working with Eaton to make the hybrid inverters even more flexible and intelligent.
One of the most important goals is to contribute to grid stability. One feature that has already been implemented is surplus management for heat pumps connected to a PV system supplied by IVG Energy Solutions. Heat pumps that support this function are referred to as “SG ready”, where SG stands for “smart grid”.
Paul Dyck, application engineer at Eaton, explains how this works: “Instead of feeding surplus energy into the grid, it is stored in the heating system’s buffer tank. This means that the buffer tank is heated to 110%, for example to 50 instead of 45 degrees, in order to store the energy, rather than selling it cheaply.” The advantages are obvious – the grid is not overloaded, and the operator of the solar installation makes the most of the self-generated electricity.
Result
By combining the inverters with the easyE4 and the right software, customers get a compliant plug-and-play solution, so that nothing stands in the way of using the devices in Germany. “We refine the inverter systems with technology and software from Eaton in order to be able to supply ‘products engineered and designed in Germany’,” explains Röthke.
But ripple control is just the beginning – IVG plans to take full advantage of the technical capabilities of the easyE4 by adding further options, from pre-configuration of the inverters via the control relay’s display to cloud integration. This is because intelligent load management can make an important contribution to a future-proof electricity supply.
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