I've started a new thread on this - distinct from the storage discussion.
Somewhere there are very good eMarketPlace models - I need to go back into my email archives / Google to find those - I know two groups where working on this from financial perspective during the .COM boom (I recall was offshoot from SWIFT... will have time to find this over weekend). Thought aside - interestingly - since that work was done - eBay has emerged as dominant local model - not sure what that means - but maybe some input from that. Bob Glushko from his CommerceOne days may also have insights here - I'll ping him.
Essentially I see it is critical to decouple the financial bid/marketplace stuff from the actual mechanical device level coupling. This then introduces 3 levels like a waterfall - into the whole process - and also establishes the boundaries of the grid itself - and who is controlling it - and what other grids it taps into. So you can foresee local grids, county, state and national levels, etc.
1) Purchase devices and power capability - configure and install to immediate grid system
2) Establish credentials and register as participant - along with selection of a broker - and establishing of initial credit level. Profile registered with grid broker management (echoes of your eBay profile here...).
3) Select eMarketplace and enter through broker services
This allows you to control all the financial issues - prevent gaming - and ensure orderly business is conducted at level 3 - and avoid having to make the devices themselves and messaging at that level 1) delivery - do that job.
Plus it has the added bonus that you can simply "borrow" the eMarketplace work - and use that as is - without re-inventing that.
Another sidebar - how do brokers work? Again - can have PayPal type model, or real banks involved, or digital money - but because you have pushed this to level 3 - you again avoid having to deal with that detail at level 1 messaging.
Technical note - level 1 messages merely need to have digital certificates and reference Ids that point to your level 2 and level 3 contracts and agreements.
DW