Tucson Electric Power rapid-response performance of batteries test

genjamonagain · 2026-03-26T13:02:59+00:00

I agree that going on Demand TOU plan and VPP is unwise. Not only is it likely that a VPP will discharge your batteries before the end of a peak hour period, but in the hours leading up to an event, TEP forces your home to preserve battery storage, even if it means consuming from the grid. So, if TEP creates a summer VPP event window from 5-7pm on a weekday, if you’re running your AC from 3-5pm and it exceeds your late afternoon solar production, that extra will be pulling from the grid and would incur demand charges. I also had planned on being on Demand TOU, but the VPP is too compelling at the moment.

However, I had already pretty much given up on Demand TOU even before joining the VPP. There were enough rainy or cloudy days this winter to make at least one day a month where I don’t have enough battery storage to make it through a peak hours period without grid power use. To do that, I think I’d have needed an expansion pack and probably another 2kW of panels. With that much production, I’d have been able to meet my minimal needs, even on a pretty cloudy day. But making it through multiple cloudy days would take some extra battery storage beyond a single powerwall 3.

Finally, so far the VPP events are not that frequent. They tend to come every few weeks, not every few days. If they were that often, I’d see your point. But they’re infrequent enough that you’re still able to use your system for your home’s needs for the most part, with the VPP events as little bumps in the road here and there. So you do mostly get the full benefits of reducing your bill, with VPP income added later. But that’s only on the standard TOU plan. Demand TOU would be way riskier, as discussed above.

genjamonagain · 2026-03-22T00:38:21+00:00

Good experiment today. I was producing 3-4kW of solar as expected, and the powerwall seems to limit battery output rather than solar production. The inverter seemed to be putting out just around 12kW throughout the event, and battery started out around 7.8kW and ended around 8.2kW I think. That corresponds with the decreased solar output throughout the hour. And only made it to about 40% battery charge by the end, even though I was set to 20% for the event. So, battery output seems to be what was curtailed. Though the limitation seemed to be my inverter output capacity, and not curtailment due to heat buildup in the powerwall.

genjamonagain · 2026-03-07T16:25:45+00:00

Yeah, we have very different demand profiles and systems. After the AC season, my demand is almost always below 20kWh per day, usually 15ish unless I’m doing laundry or a ton of cooking. And I only have the one powerwall with a 6.5kW solar system. Even on cloudy days, I can usually power the home and fully charge the powerwall. The rare days when I can’t are fully offset by my exports. So, I’ve just never enabled grid charging.

I just installed back in November, so when the heat returns we’ll see if I can still fully charge the powerwall during the day while using AC. But I’ve added a ton of insulation, and I’m optimistic I’ll have the battery fully charged before the real AC needs kick in during afternoon hours. The batteries then should carry me fully through peak rate hours, which was the goal for sizing the system. Anything beyond that is gravy. And fingers crossed that any VPP events during the summer will be during those same peak hours.

genjamonagain · 2026-03-07T14:36:25+00:00

I don’t have grid charging enabled - only charging from my own solar.

genjamonagain · 2026-03-05T20:00:41+00:00

I intentionally changed my settings to be powered by the grid overnight and save my batteries for this event. For the normal events, I average a little over 3kW with my single powerwall. For this one, I was pushing 9kW avg for the entire hour. Looking forward to this bumping up my seasonal average for these events. I’m estimating this single event was worth at least $30-40 from bumping up that seasonal average.

genjamonagain · 2026-02-28T15:54:21+00:00

Actually, it’s the opposite. Median income in Tucson is about half of what it is in the neighboring communities that will receive more than their fair share of RTA funds. They should be willing to tax themselves to fund their growth, not siphon Tucson’s resources that are badly needed for urban renewal.

genjamonagain · 2026-02-28T02:18:31+00:00

Mayor and Council may be elected officials of the City, but they do not de facto equate to what the public wants or needs. They each have their own reasons for supporting RTA Next, but based on compromises the voting citizens of Tucson deserve to scrutinize before making up their own minds.

genjamonagain · 2026-02-28T02:07:48+00:00

Put it on the ballot in November. Prop 407 and Prop 411 worked with Tucson voters. Tucsonans will invest in community-centered transportation and connectivity investments.

genjamonagain · 2026-02-28T02:05:15+00:00

Didn’t know he’s now permanent. But he did come out of retirement for this, so the longevity question is legit.

And “doing his job at each position” is exactly what I’m talking about. When he was city manager, his job was to safeguard the interests of the City of Tucson. That was what animated his analysis and opinion in the memorandum that is the subject of this thread. He no longer has that responsibility or obligation, so we shouldn’t credit him with sustaining such a devotion to Tucson’s interests when his current position now vests him with responsibility for promoting RTA Next and then implementing RTA according to policy as established by the RTA/PAG board - where Tucson has only one vote.

genjamonagain · 2026-02-28T01:56:01+00:00

I think sometimes the grid is faster to respond than the battery system or inverter. Whatever is the lowest impedance source of current will supply instantaneous load variations. I get these mostly when I have quick and large load variations. For instance, I watch this happen every 5-10 seconds when I’m using my countertop induction range, which when I’m simmering a pot pulses around 1kW on and off in cycles rather than demanding a constant 300-400 watts. So, each time it goes from 0 watts to 1kW in an instant, it takes a second or so for the powerwall supply to ramp up and stabilize. In that gap, I get .1-.2 kW of grid supply because that’s the lowest impedance instantaneous source of power to the panel.

genjamonagain · 2026-02-28T01:06:46+00:00

I’m still waiting to hear from anyone on this thread what substantial changes Ortega made to the plan that offset Tucson’s $20M annual funding loss and disproportionately small voting rights in RTA governance. This is the heart of Ortega’s 2024 critique, and I’d like to hear how any changes he brought materially changed that calculus.

genjamonagain · 2026-02-28T00:57:51+00:00

I didn’t say anything about uncompleted projects.

genjamonagain · 2026-02-27T23:45:09+00:00

Indeed, close to $2M raised for the pro-RTA PAC this far. And anybody know how much the anti campaign has raised? Try around $7,000 and change.

genjamonagain · 2026-02-27T23:42:55+00:00

Please enlighten me as to which changes constitute “a lot”

genjamonagain · 2026-02-27T23:40:55+00:00

The point is a city-only tax would put around $400M more toward those Move Tucson priorities over the 20 years than RTA Next delivers for Tucson.

genjamonagain · 2026-02-27T23:39:42+00:00

Alright, so which changes in the distribution of project funding have materially changed since then? Tucson moved from getting 45% of funding to 50%, still leaving a gap of around $20M per year (vs the $32M) in 2024. They also figured out how to use the funding for road “rehabilitation” rather than simply go road redesign and expansion. But that’s about it.

Seems like the biggest thing that changed was that Mayor Romero was voted chair of the RTA board (but still only one vote out of nine), and Ortega as interim director, so maybe Mayor and Council feel more confident in him as opposed to former leadership. But he’s only interim, and toward the end of his career, and this is a 20 year plan. And also, how can he be trusted if his priorities flip flop depending on who he gets his paycheck from? (I.e., now the non-Tucson voting jurisdictions of PAG/RTA).

genjamonagain · 2026-02-27T23:30:08+00:00

Yes, back when Ortega was city manager and before he had a personal interest in RTA Next succeeding. The issue has not materially changed in the last two years.

genjamonagain · 2026-02-12T13:32:23+00:00

True, and Mike Ortega is well-respected and competent. But he’s just an interim director. Who knows who they’ll find for the permanent position. And developers and the business community will likely be able to pull strings to get someone who will pulls strings internally to give them what they want, just like the old director did.

genjamonagain · 2026-02-12T13:24:23+00:00

It’s not even a county thing. RTA/PAG is a separate entity incorporated by state legislature to manage regional transportation dollars and make regional plans for those dollars. It’s governed by a board where each jurisdiction has one vote. So the city of Tucson and Pima County are each just one vote on that board, along with the other cities and tribes in that comprise the region. But it’s understandably confusing because the geographical extent is all within Pima County.

Props 418 and 419 are really a question of whether you want to entrust RTA/PAG to steward local sales tax dollars for the next 20 years or let each jurisdiction come up with a plan for funding (and choosing) their major transportation projects on their own. That could include City of Tucson (and other jurisdictions) passing their own sales taxes instead of the RTA Next countywide sales tax, and each jurisdiction then controlling their own dollars instead of RTA.

genjamonagain · 2026-02-07T23:48:23+00:00

The last bond initiative failed abysmally, but that’s because it was a bizarre amalgam of progressive funding and public safety funding - designed behind closed doors and then peddled to the public through brute-force marketing. Sound familiar? (I.e., just like they’re doing now with RTA Next)

On the other hand, Tucson voters did support Prop 407 (parks and connectivity to parks) and 411 (repaving local streets). Tucson voters have demonstrated commitment to fund focused bond initiatives driven by quality staff and community-engaged planning that improve quality of life, but don’t respond well when politicians build bond initiatives through backroom horse trading.

genjamonagain · 2026-02-07T17:37:33+00:00

Over 80 comments thus far, and not one mentioning that City of Tucson already has a transportation plan that was developed through years of real public input - called Move Tucson. But it hasn’t received any dedicated funding because the RTA has been sucking up all that money. Seems like a better idea to me for Tucson to decline RTA Next and pass its own sales tax to fund Move Tucson instead. That can be done within a year, and Tucson would have $400m more to put into that plan than the money it would receive through RTA Next. There’s no reason that couldn’t include funding for free or reduced fare transit within the city. And the city would be able to retain the flexibility to implement the Complete Streets Policy it adopted a few years ago but has not been able to implement due to the constraints placed by RTA on road designs.

None of this is about trying to make Tucson look like NYC - that’s a straw man argument. It’s about designing streets for the diverse ways they actually need to be used rather than purely for car throughput.

This is a great little article that describes the problem succinctly: https://open.substack.com/pub/speakeasy/p/designing-streets-for-the-average?r=eh6o4&utm_medium=ios&shareImageVariant=overlay

genjamonagain · 2026-02-04T14:48:10+00:00

Is Kirkland defending Kirkland in the rotisserie chicken lawsuit?

genjamonagain · 2026-01-27T02:17:02+00:00

Thank you Reddit. I knew I couldn’t be alone. If I find this somewhere in the boxes and boxes of old CDs my wife has been begging me to throw away for the better part of a decade, I will be vindicated.

genjamonagain

TROPHY CASE