If my opponent has helm of suppression that is empowered, and I reveal a hidden spell, do I have to pay 1 energy and 1 power when I reveal the spell?

Yes — you pay 1 energy and 1 power.

Hidden sets the spell's base cost to 0, but cost increases are applied after that. An Empowered Helm of Suppression is a cost increase (not part of the base cost), so the final cost is 1 Energy + 1 Power — same interaction as Vex (Rule 356.1 → 356.3; FAQ #8518).

If the Helm is not empowered, the cost is just 1 Energy. The Helm's effect is global and doesn't depend on which battlefield the hidden spell is at.