Thursday, September 17, 2015

How Demand Flexibility Can Help Rooftop Solar Beat Demand Charges in Arizona

The debate over rooftop solar has grown increasingly contentious, pitting solar PV companies against utilities in many parts of the country. But nowhere has the debate been more heated than in sunny Arizona, where many customers have flocked to rooftop solar as prices have come down in recent years. Most recently, utility Salt River Project (SRP) has introduced a demand charge for solar customers.

Already common among commercial rate structures but much less so among residential, a demand charge is a component of the overall bill based on a customer’s maximum demand (kW) each month, in addition to more-traditional charges based on total consumption (kWh).

SRP argues that it needs to recover costs from its solar customers that they impose on the grid through high demand. The utility position is that solar customers use the grid in much the same way as non-solar customers, and impose similar costs. Yet traditional rates coupled with existing net energy metering (NEM) riders mean that solar customers pay much less per month than other customers. SRP’s new rate is designed to recover the difference by imposing a charge on a customer’s peak demand each month, which generally occurs after the sun sets.

However, solar companies and others claim that this pricing structure is unfair. The largest PV developer in the U.S., SolarCity, has sued the utility, arguing that SRP is practicing anti-competitive behavior. In any case, whether the new rate is fair or unfair, it means that the PV market is growing much more slowly in SRP than it was a year ago; interconnect requests have More



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