Try to come up with at least three solutions. These need not involve three totally different energy sources. You could also have, say, three different types of wind systems.

At this stage no detailed design is necessary.

Try to describe the basic concepts as best you can, but do not make a decision yet.

Once the alternatives are identified you need to do at least a grid analysis. Some groups augment that with other techniques, such as a 'force field analysis' or a SWOT analysis.

For the grid analysis, use at least four (weighted) selection criteria.