Construction costs are currently skyrocketing

We also signed a contract with a price lock until 04/2024 in May of this year... Everyone was free to do it that way...

Where was one supposed to sign it? At that time, 40-50 cents depending on the region were normal. Basic supply was even sometimes 1 euro.

It all depends heavily on the region. Here, electricity is now also available for under 30 cents and gas for under 12 cents. It all depends heavily on your basic supplier and their purchasing behavior (long-term or short-term on the spot market).

Where should one have concluded? At that time, 40-50 cents depending on the region were normal. Basic supply sometimes even 1 euro.

It has even been pointed out here several times by others - at Mediamarkt... Would not have thought of it otherwise

Basic supply currently costs us 33.36

No, I think it makes a lot of sense if I can keep my low gas price of 7 cents per kWh and my electricity price of 28 cents, because that way I personally pay a reasonable amount for the costs incurred by the supplier. If my supplier now raises prices (which luckily has not happened yet), then they are simply pocketing the rest as profit, because the electricity price is capped at 40 cents and all customers pay this maximum price. Without a cap, the cheapest price on the market would still hold, but as it is now, it is basically an invitation to suppliers to all charge the same price, and customers give suppliers who previously had low prices a nice profit of 10 cents.

For me, the price cap has opened the door wide for price increases by providers. We get 100% green electricity from the region from our provider, the basic supplier in the area. This is produced by photovoltaic, wind, biogas, and several large hydropower plants. The production costs for this electricity have not changed in recent months. Nevertheless, the price for me as an end customer is raised from 24 cents per kWh to 43 cents per kWh. The feed-in tariff for photovoltaic has not changed. The wind turbines and hydropower plants belong to the supplier itself. There are long-term price agreements with the operators of the biogas plants. So why is this electricity now almost 90% more expensive as of January?

Perhaps your generator is no longer producing enough electricity for all its customers? At least that's how Berliner Stadtwerke GmbH explained the matter in their increase letter. They were still priced at 28,* /kWh for a long time and apparently received so many switching customers that they now have to purchase electricity. Of course, they have to do this long-term, and the futures, as I found out, are more than twice as high as ante bellum. I don’t know if that’s true, and I don’t know if it’s the same for you. However, it’s not completely implausible.

It was even pointed out here several times by others - at Mediamarkt... Otherwise, I wouldn't have thought of it

Basic supply currently costs 33.36 with us

I thought so. I myself gave the hint with MM. But why should I switch from a 17 cent rate to 30 cents when the price guarantee doesn't help me? See stromio, gas.de, etc. End of 2021. But wait, you will definitely get an increase too.