Travelling in Germany as a 17 year old. What do I need?

you need definitely more than a passport and money to come to Germany..

here the official info:

https://europa.eu/youreurope/citizens/travel/entry-exit/travel-documents-minors/germany/index_en.htm

I quote:

Travel documents for minors – Germany

In addition to their own valid travel document (passport or ID card), although not obligatory by law, all minors entering or leaving Germany are advised to carry a declaration of consentde (where possible in the languages of both the home country and the destination country) signed by the parents who have custody over them. The declarationde should show:

that the minor has permission to travel alone,
the contact details of the parents with custody,
the route the minor will take and
the contact details of any accompanying adults.

Special details for particular destinations and travel and security advice for German nationals can be found herede .

You can also find information on the rules applying in the destination country by consulting the relevant German embassiesde .

Just an addition about the issues regarding hotel bookings. It is not directly required by law in Germany to be over the age of 18 to book a hotel room, but there are so many legal grey areas and pit-falls to consider, that most hotels don't allow persons under 18 to book a room or even use a room alone, if they are travelling alone without a parent or guardian. You are also usually excluded from all online booking services like booking.com, Expedia or AirBnB. It is not necessarily sufficient that your parents book the room for you, you may still not be allowed to stay alone.

• One issue is, as jpatokal already mentioned in a comment, that you only within very restricted limits are allowed to enter a contract, which a hotel room booking legally is. If a hotel allows you to book a room on your own, even if you paid cash in advance, your parents can to a certain extent dispute this contract later and demand it annuled with the consequence that the hotel will have to return any payment already made.
• A further issue is, that even if the hotel allows you to stay, they are not allowed to grant you any form of credit. This is an issue if the hotel has accessible mini-bars or offer room-service or meals chargeable 'on the room' with payment when checking out. In theory, you could empty the mini bar and feed graciously during your stay just to deny payment when checking out, since the hotel was not allowed to let you eat on credit in the first place. Most hotels rightfully tries to avoid this situation at all.
• Even alcohol access regulation may be an issue. If the room only has rooms with a mini-bar and the mini-bar is stocked with strong spirits, they will therefore not be allowed to let you stay there alone.

All youth hostels associated with DJH (the German Youth Hostel Association) do however let guests between 14 and 17 stay alone if they have parental consent. Strictly speaking, they require you to bring a written consent declaration from your parents. I am not sure how strictly they check if you have a consent form, but it wouldn't hurt to bring one. The form seems to only be available in German, but just run it through an online translator and you will find out what to enter where. It is quite straight forward. Be aware though, that there are also plenty of hostels or youth hostels, which are not associated with DJH. These may have their own rules and may or may not allow you to stay alone.

As an EU citizen, you have a right to travel to Germany with minimal fuss. As a minor, Germany will try to protect you against running away from your parents or being abducted.

• According to German law, your legal guardians have the right and the duty to determine your locaction. They should do that in accordance with your age and maturity, so the law does not preclude traveling alone for a 17-year-old.
• Your ability to enter contracts is limited. Again the law is intended to protect minors while allowing reasonable purchases ("pocket money paragraph"). The easiest way might be if your parents book and pay for the hotel room and you just pay incidentals like food. Youth hostels accept children from 14 years with parental consent.
• For German minors leaving Germany, the border control suggests a letter stating the identity (name, date and place of birth as listed on the ID ...) of the minor, the identity of the guardians, contact details for the guardians, the planned itinerary, and if applicable the identity of supervising adults. If you have two guardians, both should sign.