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Remote Systems
Photovoltaic systems off of the utility grid.

Renewable Energy Credit (REC)
A trade-able certificate representing the generation attributes of energy derived from a qualified renewable energy source. In the U.S., formal markets for RECs are established in New England and Texas, and are developing elsewhere. Informal and voluntary markets are active or emerging in several other U.S. regions. RECs are also called renewable energy certificates, tradable renewable certificates (TRCs), "green tags", and other names.

Resistance (R)
The ratio of the potential difference (i.e., voltage) across an electrical component (i.e., a resistor) to the current passing through it. The relationship between voltage, current and resistance is described by Ohm's Law, V=IR