- LDC – “Local Distribution Company.” This is your electric utility company – the grid -- to which your building is connected. SCE, PG&E, APS, SDG&E, FPL, JCP&L, etc.
- Supplier – If and only if you have taken advantage of a deregulated electricity “customer choice” program, the Supplier is the third party to whom you pay for the generation of the electricity delivered to you by the LDC across the grid. The Supplier typically receives the KWH consumption data directly from the LDC; there is no separate Supplier meter. The Supplier normally invoices you using the same start/end meter reads as the LDC.
- PPA – “Purchased Power “Power Purchase Agreement.” Typically there are two PV ownership scenarios – either you own the system (you have financed it in some way) or you have entered into a long-term agreement with a vendor whereby the vendor has installed the PV at its cost and you have agreed to purchase 100% of the PV output at a stipulated (i.e. pre-determined) cost per KWH. Under a PPA, the invoice from the PPA is essentially a Supplier (see Supplier topic above) bill.
- NEM – “Net Energy Metering.” Excess KWH from the PV, when not needed by the building load, feeds “backwards” into the grid. In essence, the grid serves as a KWH “bank.” Excess KWH can be banked for free and withdrawn upon demand. The monthly LDC invoice shows the net KWH that passed from grid to building load, which is equal to the total KWH supplied from the grid less the total KWH fed back into the grid from excess PV production. (It is possible for the monthly net to be less than zero, a situation that should be avoided via proper sizing of the PV output.)