Working on an audit for a large retail client here in San Antonio with a 250kW solar installation under CPS Energy's solar buyback program. The utility is paying them $0.027/kWh for excess generation, but according to their filed tariff Schedule SBB, it should be based on their avoided cost which was $0.041/kWh during the measurement period. CPS claims the rate changed, but I can't find any filed amendment with the city. Anyone else dealt with CPS Energy solar buyback rate disputes?
CPS Energy Solar Buyback Rate Calculation Issues
Angela, that sounds familiar. We had a similar issue with TVA's Green Power Providers program here in Tennessee. They kept changing the buyback rates without proper notice to participants. The key was proving they violated their own tariff filing procedures. Did you check with San Antonio's utility regulatory office? Since CPS is municipal, their oversight might be different than investor-owned utilities.
Terry, good point about municipal oversight. CPS falls under City Council jurisdiction, not the PUC. I've requested all rate change documentation from the past 12 months. The client is out about $3,500 so far if the higher rate should apply. Their solar installer thinks CPS changed the rate methodology without notice, which would violate the original interconnection agreement. This is getting complicated fast.
We've seen Georgia Power pull similar tricks with their Schedule RNM renewable buyback rates. They'll quietly change the calculation methodology in their billing system without updating the filed tariff. The solution was filing a formal complaint with the PSC showing the discrepancy between the tariff and actual billing. Took 6 months, but the customer got $8,200 in refunds plus prospective corrections.
Derek's approach with the PSC complaint is solid. Here in Memphis, MLGW tried something similar with their net metering credits. We documented the billing discrepancy, showed it violated their filed Schedule NM, and threatened to take it to the city council. They corrected the billing within 30 days and issued a $2,100 refund. Municipal utilities hate public attention on overcharging customers, especially for renewable energy programs.