Everyone chasing American money knew the rule: if you want an investment from Silicon Valley, you move to Silicon Valley. Three twenty-eight-year-olds from Munich broke that rule and got both.

The company is called Furo and it builds software for industrial battery energy storage systems. Within a year of being founded it raised 4 million dollars (around 3.4 million euros), mostly from American investors, and it already has clients that far older companies do not - among them the German railway operator Deutsche Bahn.

Founders Lena Sophia Voss, Leonie Wagner and Simon Wittner studied at the Technical University of Munich, then reached Stanford and Berkeley through a programme run by Munich's Centre for Digital Technology and Management. They worked at Apple, Google X and AI startups. They had permanent job offers and visas to stay.

They came back.

"At the moment we are moving faster in Europe than we would be if we had stayed in the US," says Voss. And then she says the thing rarely said out loud in front of an American investor: "It was a decision to return to Europe not because we had to, but because we see that right now is a better time to build an energy startup in Europe than in the US."

The logic is not patriotic but arithmetical. The problem they solve - industrial companies with electricity bills that are too high - is sharper in Germany than in California, after years of one energy crisis after another. And the clients and the network are here. "If you are an early-stage company, most of the time everything depends on your network and how close you are to your customers," says Voss. When the company was in an American accelerator under its old name Lumera Energy, the work was harder precisely because of the distance.

There is a blunter calculation too. "If you compare an engineer's salary in the US with the one in Germany, it is simply much cheaper," says Voss. American investors doubted whether the company would find people at all within the budget it had set - a budget that in Germany sits right at the top of the pay scale. The quality of the staff, she says, is the same, and people are more available because there is not the same competition from the big tech companies.

This is not a story about breaking with America. On paper Furo is registered in Delaware, the round was led by the American TQ Ventures, and Sheryl Sandberg's fund is among the investors. The founders fly to the US three or four times a year. The formula is not "stay home" but "take the money there, build the product here".

And that is exactly where the story starts to sound familiar. Every year engineers leave Macedonia with the same degrees and the same offers, and almost never come back with capital behind them. The difference is not talent - the difference is whether a network exists that will recommend you to your first client when you return. The Germans have that network through their universities. Who is building it here?