I totally agree. Hopefully the approach works and isn't locked by some horrible patents so that other companies are prevented from actually selling it.

Monthly base fee starts at 300€, which will be reduced by [...] which can amount to up to 150€

Yeah if it was more than the 10 MWh they've mentioned on their website, perhaps it would be good enough for my house. But I think I reached over 2000 kWh of electricity consumption a month this winter thanks to my heat pump and possibly more than that in briquettes that I use for my central heating furnace. The 10,000 kWh they talk about is sadly not enough for my soviet-era built house, nor is my roof big enough for a meaningful amount of solar (it's complicated... big house, small roof, not all of the roof useable for solar). If I'd have to get 2 or 3 units and they end up costing me significantly more than the 300€ a month? No thanks. My highest electricity bill in the winter was about 330€ and yes, I also burned about 500€ worth of wood briquettes that month, but in the summer I pay less than 100€ and this was a freakishly cold winter, so normally it wouldn't cost as much (and I'm also now older and wiser and will keep a bigger stockpile because the prices do go up in the winter, something I've experienced before).