You said: One idea that my team mate came up with, I don’t like, because it would cut the amount of electricity generated, but I know that the architects will love it. My question is, is it ethical to not inform the architects of this other way of doing it?
The answer to your question depends on who the ultimate client of the project is. For example, is there an external client who is not part of the team who is setting the priorities for the team? If yes, then I feel your client should be the one to decide. If they haven’t articulated their requirements clearly enough at this point, then the project manager or someone in a similar role will need to ask them.
I say this because it’s entirely possible that the objectives of the project can be met even if the amount of electricity generated is lower than what you’d like. Meaning, it’s possible that even with less electricity, the project as a whole is still considered a success because it met the stated objectives of the project.
To put it another way, the question sounds very much like a case of Local Optimization vs. Global Optimization. Meaning, you are choosing local optimization by prioritizing your subteam’s ability to generate electricity, at the expense of eliminating some options for the other subteams, and therefore eliminating options for the project (global) as a whole.
Now it would be a different story altogether if the idea that you don’t like will reduce the electrical generation so severely as to render the entire project a failure. If that’s the case, then by all means you should not even mention the idea because it is not a viable suggestion.
But if the overall project objective can still be met even with reduced electrical generation, then I think it’s only right to present the option, but you also have an obligation to make it clear to everyone what the implication is—so that the client (and the team as a whole) understands the implications, and can make an informed decision.