Who else is in the aggregation?
Most customers have load profile or pattern of usage that is not constant. Do the load profiles of other participants in the aggregation compliment that of your organization? If so, the aggregator may be able to get a better price than a collection of similar loads.

Are the other participants in the aggregation stable businesses with a track record of sound financial management?
A power supplier will want to know whether it can rely on the load it is purchasing from the aggregator. If the supply is not stable, members of the aggregation may end up paying more for energy to compensate for some other participant's poor risk profile.

At what point in the membership process am I actually committed to a supply contract?
Many aggregations require members to commit if the price is lower than a pre-determined benchmark, such as the "standard offer". While this type of commitment may seem risk free, by accepting this condition you are eliminating any other options that might be available at the time that the supply contract would go into effect.

What are the costs to become a member and participate in a supply offering?
Whatever costs are assessed to members, they must be weighed against the supply offering in order for prospective members to make an informed business-decision. In addition to a straight membership fee, there may be ongoing fees throughout the term of the supply contract.

What are the terms under which a business is asked to join an aggregation?
Is there an energy purchase agreement between you and the aggregator? Is there a purchase agreement between the aggregator and the power supplier?

Most importantly, who is running the aggregation?
If people with little or no experience manage the aggregation, your organization may be better off negotiating independently or financing an alternative aggregator.

Does the aggregation provide opportunities for member involvement?  
It is important that the aggregation allows for ample representation of its participants and opportunities for input from participants. For example, the Maine PowerOptions electricity program uses an institutional advisory committee to help determine what elements of the program are important for their types or organizations. This institutional advisory committee consists of representation from the various member segments (i.e. healthcare, higher education, utilities, local governments, and non-profits).