Anyone else auditing bills for Seattle City Light's battery storage pilot program? I've got two residential clients enrolled and both are seeing weird billing anomalies. The time-of-use credits for battery discharge during peak hours aren't calculating correctly. Program is supposed to pay $0.45/kWh for discharge between 6-9 PM but bills show $0.28/kWh. Called SCL three times and keep getting transferred between departments. Their billing system apparently wasn't designed for this program.
Seattle City Light battery storage pilot program billing errors
Sacramento Municipal Utility District has a similar program and we saw the same issues in year one. Problem is most utility billing systems treat battery storage like regular solar net metering. They can't handle the complexity of time-differentiated buy/sell rates. SMUD had to manually adjust bills for the first six months until they got their system updated. Your clients should document everything and demand manual corrections.
Eversource in Connecticut launched a battery pilot last year and it was a billing nightmare. The meters couldn't properly track battery charge/discharge cycles versus direct solar production. Customers were getting charged for energy they never used because the system thought they were drawing from the grid when they were actually using stored solar. Three different meter replacements before they got it right. Make sure your clients have proper monitoring equipment independent of the utility meter.
Good point about independent monitoring. Both my clients have SolarEdge inverters with battery monitoring but SCL says they can only bill based on their net meter readings. Problem is their net meters are old electromechanical units that can't handle bi-directional flow with time stamps. One client's meter was actually running backwards during battery discharge periods. SCL finally admitted they need to upgrade to smart meters for all pilot program participants.
Huntsville Utilities did a small battery pilot in 2016 and learned this lesson the hard way. You absolutely need interval data meters - at minimum 15-minute intervals, preferably 5-minute. Without that granular data, there's no way to properly compensate for time-of-use battery services. They also need separate meters for solar production vs. battery discharge if you want accurate accounting. Most utilities are trying to do this on the cheap with existing infrastructure and it doesn't work.
Similar issues with Dominion Energy's pilot program here in South Carolina. The real problem is utilities are treating battery storage like it's just another solar installation when it's completely different. Batteries can provide grid services like frequency regulation, demand response, and peak shaving that should be compensated separately. But their billing systems lump everything together as "distributed generation." Need separate tariffs and metering for energy storage services.
Update - SCL finally installed smart meters for both clients last week. Immediately started seeing proper time-of-use data and correct compensation rates. They're also crediting back the billing errors from the past four months - about $340 for one client and $275 for the other. Apparently they've had similar problems with all 47 pilot program participants and are doing system-wide corrections. If you have clients in this program, make them file complaints now to get their money back.
Cincinnati Gas & Electric is looking at launching a similar program and asked me to consult on avoiding these exact issues. Key recommendations: 1) Smart meters with 5-minute intervals mandatory, 2) Separate tariff schedules for energy vs. grid services, 3) Real-time billing system that can handle multiple simultaneous transactions, 4) Customer portal showing detailed battery performance data. Most utilities are trying to retrofit old systems instead of building proper infrastructure from the start.
The technology exists to do this right - companies like Green Button Alliance have standardized data formats for complex distributed energy billing. Problem is utilities don't want to invest in proper systems because they see storage as a threat to their business model. They're hoping these pilot programs fail so they can justify restrictive policies later. Document every error, every delay, every runaround - this data will be crucial for future regulatory proceedings.
Entergy Arkansas is considering a battery pilot and I'm already warning them about these issues. Showed them examples from Seattle, Sacramento, and Connecticut - all the same problems because they're all using the same outdated approach. The solution is treating battery storage as a grid asset that provides services, not as customer generation that gets net metered. Need separate interconnection agreements and compensation mechanisms for each service the battery provides.
Avista here in Spokane is watching Seattle's pilot closely before launching their own. They've already committed to smart meters and separate service agreements for battery participants. The key lesson is you can't just bolt battery storage onto existing net metering programs - it requires completely different billing infrastructure. Utilities that try to take shortcuts end up with angry customers and billing nightmares like Seattle experienced.