I've got a client in Cheyenne with a Tesla Powerwall 2 and 8.5kW solar system and Rocky Mountain Power is billing them like they're running a small factory. The battery is supposed to optimize their time-of-use rates but instead they're seeing demand charges of $240/month when they never exceeded 3kW before the installation. RMP claims the battery charging creates artificial demand spikes. Has anyone successfully challenged this kind of billing interpretation? The client is furious and threatening to rip the whole system out.
Tesla Powerwall billing nightmare
Brenda, I've seen similar issues with Xcel Energy here in Denver. The problem is that most utilities treat battery charging as regular load, not as part of the renewable energy system. When the Powerwall charges during off-peak hours, it can create demand spikes that trigger commercial-level demand charges if the customer is on the wrong rate schedule. First question: what rate schedule is your client on? They might need to switch to a residential TOU rate that doesn't have demand charges.
Scott, they're on RMP Schedule 1 residential, which shouldn't have demand charges at all. That's what makes this so frustrating. RMP is claiming that the battery system makes them a "special contract" customer and automatically moved them to Schedule 6A small commercial. The client never agreed to this rate change and wasn't even notified until they got the massive bill. I think RMP is way out of line here but I need ammunition to fight back.
This sounds like utility overreach to me. Here in Missouri with Ameren, they tried similar tactics in 2017 but backed down after pushback. The key is proving that the battery is integral to the solar system, not a separate commercial operation. Brenda, do you have documentation showing the Powerwall was installed specifically for load shifting and backup power? If it's programmed for self-consumption optimization rather than grid arbitrage, that strengthens your residential classification argument.
I dealt with a similar situation with Georgia Power last year. The client had a LG Chem battery with 6kW solar and GP tried to reclassify them as commercial because of "bidirectional power flow." We fought it by demonstrating that the battery never exported power to the grid - it only stored solar generation for later household use. Got them back on residential rates and recovered $1,800 in overcharges. The key was showing the battery programming settings and three months of detailed load data.
Eleanor, that's exactly the approach I was hoping to take. The Tesla app shows the Powerwall is set for "self-powered" mode and has never exported stored energy to the grid. It only discharges to meet household loads during peak rate periods. I've got screenshots going back to installation showing the settings haven't changed. Rocky Mountain Power needs to prove this is somehow different from a residential application, and I don't think they can.
Brenda, one more angle to consider - check Wyoming's net metering regulations. Most states have specific language protecting residential customers with energy storage from being reclassified as commercial. Georgia's rules specifically state that batteries paired with residential solar remain residential applications. If Wyoming has similar language, RMP doesn't have a leg to stand on. Also document any communications where they admitted the rate change was automatic rather than based on actual usage patterns.
Greg raises a good point about state regulations. Colorado passed specific protections in 2018 after Xcel tried similar tactics. Brenda, you might also want to file a complaint with Wyoming's Public Service Commission. Even if RMP technically has authority to reclassify customers, they still need to follow proper notification procedures. Moving someone to commercial rates without notice could violate state consumer protection rules regardless of the technical merits.
Update: I filed the PSC complaint on Monday and within 48 hours got a call from RMP's regulatory affairs office. They're "reviewing the classification" and have agreed to hold the account in dispute status while they investigate. Reading between the lines, I think they know they screwed up. The CSR admitted they've had "several similar complaints" recently, which suggests this is a pattern rather than an isolated incident.
That's great progress, Brenda. The fact that they're backing down so quickly suggests they don't want this to become a public issue. Document everything and make sure any resolution includes a commitment not to reclassify similar residential battery installations in the future. Other clients in RMP territory will thank you for setting this precedent.
Brenda, this is exactly the kind of case we need to share widely. I've seen utilities in Tennessee, Texas, and California try similar overreach tactics with residential battery storage. The key is pushing back hard and fast before they establish a precedent. Would you be willing to present this case at our next regional meeting? I think a lot of members would benefit from hearing your approach and the outcome. Great work standing up for your client.