Solar Magazine – Uproar over Kubie preventing inverter solar panel failure: does the product live up to its promise?

Solar Magazine gives young companies that want to make a difference in the energy transition space to present themselves in the section from startup to scale-up. In the latest edition, it was Kubie’s turn. The company markets a handy transformer that can be mounted behind the main switch in the meter cabinet, and wants to scale up production considerably and also sees the solar cell installer as an important sales channel.

24-hour simulation
“Kubie lowers the voltage in a house to around 220 volts,” said owner Henk Dinkelaar. “The benefit is a much lower energy consumption for many appliances. Tests by the Technischer Überwachungsverein (TÜV) – a 24-hour simulation of the power consumption of an average family with modern and highly energy-efficient appliances – resulted in savings of 12.6 percent in electricity. There are also a great added benefit that we were pointed out by customers with solar panels on the roof who regularly suffered from inverter failure when the mains voltage rose too high. That problem was completely eliminated after installing Kubie.’

Skeptical reactions
So much for Kubie’s promise. Solar Magazine received a flurry of skeptical responses from readers. They especially question the savings requirement and the effects on the local electricity grid and often also the legality.

“There are undoubtedly some devices that actually become slightly more efficient at a slightly lower voltage. But most of them become more inefficient than more efficient with a lower voltage,’ says Albert Waninge, software developer and domotics expert.

Hans Roes from Modpro points to a study from the Swedish research institute RISE from 2019. ‘That study shows that Kubie himself also consumes energy. The one they tested had a consumption of 23 watts, which is just over half a kilowatt-hour per day or 201 kilowatt-hours annually from a system designed to help you save on your electricity consumption. It is nothing; enough energy to drive the average electric car somewhere between 1,000 and 1,500 kilometers.’

“It is not for nothing that solar panel inverters must switch off at 253 volts. That excitement also comes to users without Kubie. If the inverter is “fooled” by artificially lowering the voltage and continues to supply the grid, the grid voltage (on the street) can exceed 253 volts, which can be dangerous. Is this allowed?’ This is written by Hans Welschen, who has been developing solar systems and system components for over 40 years.

Pros and cons
Solar Magazine asked DC, EV & Power Electronics expert Henry Lootens to shed light on the pros and cons of Kubie. He is also critical, above all of the savings requirement. “Reducing the voltage in a house, for example to 220 volts, will reduce the energy consumption of ohmic devices. However, this does not apply to equipment with electronics such as computers and LED lighting, and for example today virtually all modern washing machines, dryers and ovens. In addition, a transformer that does nothing but drop the voltage by a percentage is by definition lossy. So you can make nice correct calculations, but they have to be substantiated on all sides; be transparent and transparent. That’s not my main warning though. People with solar panels don’t want their inverter to fail because the grid voltage exceeds 253 volts, that’s their right, but if you continue to supply power in such a case, which this transformer enables, the grid voltage in your area may exceed the maximum standard . So you are effectively throwing your problem over the fence at the neighbors, which may cause their equipment to break. Also, network operators have no way to trace the wedge the to the problem, because they are not allowed to read smart meters without further ado. In general, the network managers are also not allowed to interfere in what happens behind the energy meter. In other words: we are talking about an individual solution that does not contribute to solving a growing societal problem – that of the lack of network capacity – but rather counteracts it. I therefore wonder if this is allowed and I am curious about Kubie’s proof of the promises made.’

The place
Solar Magazine sends Lootens’ comments to grid operator Stedin. Is technology like Kubie a desirable development? ‘We understand that consumers find it annoying that they miss out on income because there is a temporary lack of feed-in when inverters are switched off,’ says Stedin spokesman Koen de Lange after consulting with the technical expert in the organization. “We have not tested Kubie and rely on the information Kubie provides in the article on Solar Magazine’s website. If the device lowers the voltage at the user’s home, the voltage in the street and thus at the neighbors may increase. If the voltage rises too high, it may short electrical equipment life We do not yet know whether this device is a suitable solution to voltage problems and ask the entrepreneur to demonstrate it to us.’

Answer Kubie
Henk Dinkelaar is disappointed by the reactions to the story about Kubie. ‘We also state that Kubie does not skimp on all equipment. But the most reliable measuring institute in the world, TÜV, has shown in a study that an average of 12.6 percent is saved in a home with all A+++ household appliances used. Contrary to what some claim, Kubie’s own consumption is also measured as actual consumption. The cited Swedish study was conducted with 100 LED lights connected to a Kubie. It is of course not at all representative of the total consumption in a home.’

End of line
Dinkelaar completely rejects the claim that Kubie can cause an increase in grid voltage. According to him, the problems with high voltage in homes occur at the end of the line. ‘If a mains voltage of 249 volts is supplied to such a house, the inverter will add 3 volts on top of this and 252 volts will be supplied back,’ says Dinkelaar. ‘With Kubie, the voltage is first reduced from 249 volts to 223 volts. Here comes 3 volts on top, which gives 226 volts. This voltage increases again to 249.6 volts when fed back by the Kubie. The voltage injected into the grid is therefore 2.4 volts lower than the standard situation, so the grid voltage increases considerably less than without Kubie. Only in the situation where the mains voltage exceeds the permitted mains standard of 253 volts, Kubie will not be able to prevent the output voltage from also being higher. But our network operators always ensure that the network standard is not exceeded.’

Misunderstandings
Dinkelaar also responds to Stedin’s invitation to a demonstration of Kubie. He calls the product an excellent solution for situations where too high a voltage causes problems with the inverters. ‘These can be solved with Kubie at a low price. Reinforcing electric cables – which will eventually have to be done – is a long-term and much more expensive solution. It is a pity that there are still many misunderstandings about Kubie. We want to help them out of the world. Anyone who has questions is therefore welcome.’

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