Dropped by GSparx recently, they still haven't got anything solid for residential and the person in charge isn't forthcoming (probably due to it being still in the discussion stage), but from what I gather, this is how it will work.

Zero upfront cost initially but you will be leasing the whole setup for at least 10 years. Meaning every month you have to pay the lease. As for the extra electricity generated, it seems that TNB/GSparx will 'store' it as credit for you to use at a yet to be determined amount.

IMHO, I think this is how it will go, you pay nothing upfront, the company comes and fix it up. Say you provide RM500 of power back to TNB, minus the lease (say RM450), the balance will be deducted from your monthly electricity bill. Hence maybe that was meant by, "you will see a reduction of 10% from your electricity bill".

If this is the case, then you need to have a roof big enough to cover the lease cost and also to earn some extra credits to cover your monthly bill.

These are all conjectures as they haven't come out with the program yet. I think their policy should be not to install for you if it's less than what you can generate. Or maybe after 10 years the panels belong to you. Have to wait for their deal.